Exam 2 L.O

The prevalence of the D antigen among African Americans:

92%

The prevalence of the e antigen among Caucasians in the U.S.

98%

Weak reactions in a reverse type can often be strengthened by

incubating the test tubes at room temperature or colder for 10-15 minutes, and then centrifuging

Describe the clinical significance of Anti-Lea and Anti-Leb in terms of: Transfusion compatibility, HDFN, Complement activation, Potential for causing transfusion reactions, Reaction strength in antibody screening and identification test procedures

lewis abs are generally considered insignificant in blood transfusion practices because: - neutralized by lewis Ag in secretions (plasma) -Ag positive donor cells can become Ag negative in recipient. The antigens can elute from the RBC membrane as easily as they absorb onto it. -lewis abs are implicate in HDFN. fetal blood is Le(a-b-) so even if maternal ab is IgG and crosses placenta there's nothing for the ab to attach to.

Although several of the following answers may be correct, which one of the following is the most likely cause of the reactions below, because it is more commonly encountered? Anti-A: 0, Anti-B: 3+. Anti-D: 0, Rh con:0, A1 cell: 0, B cell: 0, Interpretation: discrepant

missing reverse type reaction due to very old or very young age

For which of the following would a saline replacement technique be the most appropriate step to resolve an ABO discrepancy?

pseudoagglutination is suspected in the reverse grouping

A patient's serological Rh phenotypic results are shown below. The most likely genotype is: Anti-D; +, Anti-C:0, Anti-E: +, Anti-c:+, Anti-e:0

R2R2

A patient's serological results are shown below. The most likely genotype is: Anti-D: +, Anti-C: 0, Anti-E: +, Anti-c: +, Anti-e: +

R2r

Which of the following is positive for the G antigen?

R2r

Translate the five major haplotypes from Fisher-Race to Wiener nomenclature.

Rh positive (fisher to wiener): -Dce = R0 -DCe = R1 -DcE = R2 -DCE = RZ Rh negative (fisher to wiener): -dce = r -dCe = r' -dcE = r" -dCE = ry

Please translate the following into Wiener nomenclature: Dce/dCE

Rory

Given patient clinical information and pretransfusion testing results, correctly identify the most likely Lewis system antibody(ies) present.

review case studies in advanced lewis system lecture

Given the results of forward and reverse typing, correctly interpret the ABO group of the patient

review example problems/youtube videos for practice

Given the A, B, O, H, Le and secretor genes inherited, determine the antigens present in the secretions and on the RBC membrane.

review lecture note questions - intro to ABO blood groups

Given the ABO, H, & Lewis antigens present on the RBCs and in the secretions, predict the most probable genotype of the individual.

review lecture notes questions- intro to ABO blood groups

Most Rh antibodies are ________________________, and react best at __________.

unexpected, 37 degrees C

Recall the "rule of reciprocity."

you form Abs to antigens you lack

resolve weak or missing reactivity in the forward typing.

-weak ABO subgroups: test cells w/ anti-A,B reagent, may require genotype testing to confirm -leukemia/malignancy: can result in temporary loss of expression of ABO antigens, check patients diagnosis/history -transfusion of group O RBCs: check transfusion history -bone marrow transplant: possible group A receiving group O BMT, check patients diagnosis/history

Which of the following have been associated with decreased Lewis antigen synthesis resulting in Le(a-b-) phenotype?

-parasitic infections -bacterial infections - alcoholic cirrhosis -stomach cancer -pregnancy

Which of the following can result in weak expression of the D antigen?

-partial D (mosaic) -C gene in trans position to D gene - genetic transmission of Weak D genes

Describe the Rhmod phenotype

-partial suppression of Rh gene expressions due to the mutations in the RHAG gene -exhibit similar features to Rhnull but symptoms are less severe

state the purpose of fischer-race nomenclature and analyze their individual use in the clinical setting.

-purpose: genetics and serology -based on closely linked allels D, C/c and E/e -d is an amorph and doesn't produce a phenotypic product -d = absence of D antigen

Seeds from the Ulex europaeus (common gorse) plant produce a lectin that

-react stronger with A2 cells than with A1 cells -react strongly with Group O cells

Which of the following phenotypes will react with anti-f?

-rr -The f antigen is expressed when c and e are in cis position (ce) on the same haplotype.

Which of the following genotypes may secrete Lea substance?

-se/se -Se/se -Le/le -The le/le genotype lacks the Lewis gene; therefore, no Lea substance can be synthesized.

Illustrate the effect the secretor genes have in the production of H, A, B, & Lewis antigens in the secretions.

-secretion of A, B and H substances in saliva and other body fluids is controlled by a pair of alleles, Se and se, (secretor genes). -Secretion of A, B and H soluble substances is accomplished even when only one locus carries Se. -There can be no Se when se is present on both chromosomes. (se is an amorph). -The secretor genes are not linked to the ABO locus, they are inherited independently.

Describe the characteristics of Rh antibodies.

-start out at IgM then replaced by IgG. usually IgG detected, if IgM is detected that means new abs are forming. -can cause hemolytic transfusion rxns in newborns -clinically significant -compatibility -complement mediated intravascular hemolysis doesnt occur b/c of position effect (rh abs are too far apart from each other on membrane)

strength of reactions with anti-A, anti-A1, anti-A,B, and A1, A2, and B cells.

-strongest to weakest rxns: -A1, A2, A3 (anti-A and most anti-A,B), Ax (anti-A), Aend (anti-A and anti-A,B), Am (anti-A and anti-A,B) -more binding sites = stronger rxn -weaker supgroup = stronger rxn with anti-h

Describe in detail each of the following ISBT-recognized Lewis antigens and the antibodies formed against them: Lea

-the Le gene produces L-fructosyltransferase to add L-fucose to the basic precursor substance -L-fucose converts type 1 chain to Lea

Define the term transitional phenotype as it relates to testing intervals and age of the patient.

-this has to do with Le + Se genes and antigen expression -if a person has inherited Le and Se they eventually end up typing as Le(a-b+) -transitional period lasts 10 day to 6/7 years. will have the phenotype Le(a+b+)

Differentiate the oligosaccharide precursor chains found in the secretions versus those found on the RBC membrane.

-type 1 chains: soluble glycoproteins found in secretions -type 2 chains: glycoproteins, glycolipids, an glycosphingolipids found on RBCs

Cord blood is expected to have which of the following Lewis phenotypes?

Le(a-b-)

The RBCs of a nonsecretor (se/se) adult will most likely type as

Le(a+b-)

Compare and contrast the formation of Lewis antigens with the formation of A and B antigens on their respective precursor substances.

-A antigen on RBC: N-acetylgalactosamine -B antigen on RBC: d-galactose

Please identify the following structure:

ALeb

Inheritance of the B gene directly encodes the production of

Alpha-3-D-galactoslytransferase

diagram production of B antigens beginning with the precursor substance and including the action of the B gene

B gene: add alpha-3-D-galactosyltransderase to D-galactose -B antigen: refer to diagram

Why are anti-Cw antibodies not commonly encountered in routine blood bank testing?

Because the Cw antigen is a low incidence antigen. Few people are exposed to it.

An adult individual has inherited the following genes: h/h Se/- le/le B/O What will the person's ABO red cell phenotype be?

Bombay phenotype

Which of the following is a possible correct genotype for an offspring born to parents with the following genotypes? Mother: R1R1 Father: R2r

DCe/dce

Which of the following can result in a complete but weakened expression of the D antigen?

DcE/dCe

Please correctly translate the following haplotype: Ro

Dce

The Lewis gene is known as

FUT-3

Lewis antibodies are commonly encountered in prenatal specimens; however, they are not implicated in hemolytic disease of the fetus and newborn (HDFN). Why is this?

Fetal cells are Le(a-b-)

Which Lewis phenotype is the most common among Caucasian adults in the U.S.?

Le(a-b+)

An adult individual has inherited the following genes: H/H Se/- le/le A/O What will the person's Lewis red cell phenotype be?

Le(a-b-)

An adult individual has inherited the following genes: H/H Se/Se Le/Le A/O What soluble substances will be found in this individual's secretions?

Lea, Leb, A, and some H

The following structure is found circulating in the plasma of an individual. The structure is soluble

Leb substance *draw pic in notes/album*

Amorphic-type Rhnull is characterized by

deletion of the RHD gene and mutations in the RHCE gene.

A, B, and H antigens found on the RBC membrane can exist as

glycosphingolipids

Which of the following statements regarding precursor chains is correct?

Type 1 chain refers to a beta 1 to 3 linkage in which the number one carbon of the galactose is attached to the number three carbon of the N-acetylglucosamine sugar of the precursor substance.

Which of the following lectins binds to the H antigen?

Ulex europaeus

Of the following, what is the most probable cause of the reactions seen below? Anti-A: 0, Anti-B:0, Anti-D: 0, Rh control: 0, A1 cell: 0, B cell: 4+, interpretation: discrepant

Weak subgroup of A

the Rh blood group system examples

http://downloads.lww.com/wolterskluwer_vitalstream_com/sample-content/9780781782043_Quinley/samples/SAA_Chapter10.pdf

Please correctly translate the following haplotype: r"

dcE

Recall the enzymes coded for by the H, A, and B genes, and which sugar is attached in the formation of each antigenic structure.

-H: alpha-2-fucosyltransferase, fucose (sugar) -A: alpha-3-N-acetylgalactoseaminyltransferase, fucose (sugar) -B: alpha-3-D-galactosyltransferase, fucose (sugar)

Translate the five major Rh antigens from Fisher-Race to Wiener nomenclature.

- D (antigen) = R (wiener) - d (antigen) = r (wiener) - C (antigen) = 1 or ' (wiener) - E (antigen) = 2 or " (wiener) -wiener is shorthand

Translate the five major genotypes from Fisher-Race to Wiener nomenclature.

- DCe/dce (fisher) = R1r (wiener) - DCe/Dce = R1R1 - dce/dce = rr - DCe/DcE = R1R2 - DcE/dce = R2r - DcE/DcE = R2R2

Which of the following phenotypes can form anti-Leb antibodies?

-Le(a+b-) -Le(a-b-)

Anti-Lea antibodies can be formed by which of the following phenotypes?

-Le(a-b-) -Anti-Lea is only formed by Le(a-b-) individuals. Le(a-b+) individuals do not form anti-Lea antibodies because they have Lea substance in secretions.

A person inherits the following genes: Se/se, H/h, A/B:

-Person is a secretor -A antigens on the RBC -B antigens on the RBC -A, B, and H antigens in the saliva

Describe the changes in phenotypes and presence of Lewis antibodies during pregnancy and clinical significance.

- all neonates type as Le(a-b-). if a person has inherited Le and Se they eventually end up typing as Le(a-b+) in this process: -fetus and neonate: Le(a-b-) -after 10 days: Le(a+b-) -transitional phenotype, 10 days to 6/7 years: Le(a+b+) -after 6 to 7 years: Le(a-b+)

Recall the Lewis phenotype frequencies in both the Caucasian and the African American populations.

-Le/le = Le(a-b-): 22% in african americans, 6% caucasians -Le(a+b+): rare in both caucasians and african americans, but found in 10-40% of asians

diagram production of H antigens beginning with the precursor substance and including the action of the H gene

-H gene: production of alpha-2-frucosyltranferase adds to the type 2 precursor chain to make fucose -H antigen: 99% of populations RBCs -refer to diagram in ppt

Explain the principle of the Weak D test. Identify when it is necessary to differentiate Weak D positive from D negative persons.

-No differentiation of weak D causes -policies regarding testing of weak D -regulatory requirements

Describe the Rhnull phenotype.

-"Rh deficiency syndrome" -lack all Rh proteins: ---/--- -2 types: regulator and amorphic -regulator: mutation in the RHAG gene. problem w/ gene on chromosome 6. RHAG must be present to express Rh. RHD and RHCE genes are usually normal -amorphic: RHAG gene is normal. mutations in RHCE and common deletion of RHD gene this compromises the integrity of cell wall b/c Rh proteins are transmembrane proteins -more rare than bombay

Compare and contrast the subgroups of A and B (A1, A2, A3, Ax, B, B3, and Bx) in terms of efficiency of antigen production, tendency to produce anti-A1 or anti-B, and strength of reactions with anti-A, anti-A1, anti-A,B, and A1, A2, and B cells.

-99% of all group A are either A1 (80%) or A2 (20%) -A1: more complex, phenotype is mostly A1 antigens (plus some common A), more antigen sites. stronger rxn -A2: only has common A, less antigen sites. anti-A1 produced by 1-8% of people. weaker rxns -A3: mf w/ anti-A and anti-A,B reagents -Ax: not agglutinated w/ anti-A but do agglutinate w/ most anti-A,B. could be mistyped as O -B, B3, Bx: subgroups of B are very rare and less frequent than A subgroups

diagram production of A antigens beginning with the precursor substance and including the action of the A gene

-A gene: start w/ chain from H antigen. adds alpha-3-N-acetylgalactosaminyltransferase to N-acetylgalactosamine . converts H to A antigen -A antigen: this is the common A in its most simplified form

resolve unexpected reactivity in the reverse typing.

-A2 phenotype with A1: run lectin test/biflorus test (should be neg), antibody screen w/ I.S. (room temp) -cold reactive alloantibody: perfrom biflorus test (should be pos), perform antibody identification panel (I.S should be pos) -cold reactive autoantibody: perform biflorus test (should be pos), perform antibody screen (all I.S results pos), can test plasma against cord blood -pseudoagglutination: saline replacement -transfusion of incompatible plasma components: investigate by checking transfusion history -recent infusion of IVIG: drug history

Which of the following is associated with the Bombay phenotype?

-ABO forward and reverse type appear to be Group O; patient has strong reactions with screening cells due to anti-H antibodies but a negative autocontrol

Describe in detail each of the following ISBT-recognized Lewis antigens and the antibodies formed against them: ALeb

-Anti-ALeb reacts with group A Le(b+) and AB Le(b+) RBCs -person has inherited an A gene -alpha-3-n-acetylgalactosaminyltransferase -Leb antigen.

An R1R2 male mates with an r'r female. Which of the following genotypes are possible in the offspring?

-DcE/dce -DcE/dCe -DCe/dce

Which antigens are present on RBCs of the genotype R1R2?

-E, e, C, c, D -In the Rh blood group system, d represents the amorph (silent allele). Therefore, d is not an antigen that is expressed. R1R2 is DCe/DcE in Fisher-Race nomenclature.

Which of the following patient data best reflects the discrepancy seen when a person's red cells demonstrate the acquired-B phenotype?

-Forward grouping: AB -Reverse grouping: A

Compare and contrast the following Rh antigens according to definition, frequency, antigenic reactivity, and recipient/donor compatibility: G

-G antigen is unique, it is unlike D/C/c/E/e -present on any cell that carries either the D or C antigen. G is absent when a persons RBCs lack both D and C -G is present: D+C+., D-C+,D+C-. G is absent: D-C- -in blood transfusion anti-G doesnt matter. -blood given: rr = dce/dce

Compare and contrast the result of inheriting H/H or H/h genes versus the result of inheriting h/h.

-H gene is present in more than 99% of the population (HH or Hh). forward type would look like group O -h/h is known as Oh or the "bombay" phenotype. may inherit ABO genes but b/c the H antigen isnt formed, no ABO expression can occur. reverse type would have abs to A,B form anti-A,B and anti-H

Confirmation of A2 subtype includes testing the patient's: Choose all that apply

-RBC + Dolichos biflorus produces a negative reaction - Serum with A2 cells produces negative reaction

Explain the reason there is a reverse typing with the ABO blood system and not with other blood group systems.

-Reverse typing is obligatory, b/c it can help to reveal mistyping, weak A subgroups with anti-A1 and unexpected IgM antibodies. Any discrepancy between the results of the tests with serum or plasma and red cells should be investigated -not done on other blood group systems b/c a person should not have preformed antibodies to the D antigen, unless they have previously been alloimmunized to the D antigen through transfusion or pregnancy

Define the purpose of Rosenfield and ISBT nomenclature. [Note to the learner: the Rosenfield and ISBT nomenclature need not be memorized. The student should be aware of the purpose of each.]

-Rosenfield: described the presence or absence of the antigen on the RBC. there is no genetic basis. D=1, C=2, E=3, c=4, e=5 -International society of blood transfusion numeric terminology (ISBT): each antigen assigned to the Rh blood group is given a unique number to complete the 6 digit #. Rh blood group is assigned prefix 004. -advantage of ISBT over rosenfield is that it is purely a numeric system, which is easier for data processing.

Which of the following phenotypes will react with anti-G?

-Rzr - Dce/dce - ryr" - dCe/dce -The G antigen is almost always expressed when either D and/or C is present

You have identified anti-C in a patient's serum sample. Transfusion of which of the following units of RBCs could lead to an antigen-incompatible transfusion reaction?

-Rzr -R1R2 -R1r -r'r -R1R1 -ryry

Describe appropriate follow-up testing that is necessary in the resolution of ABO discrepancies (STEP 1)

-Step 1: repeat the test -technical errors: specimen mix up, forgot to wash cells, incorrect cell suspension, failure to add reagents/sample, misses hemolysis rxn (read as neg), didn't follow up procedure, incorrect centrifugation, incorrect interpretation.

Describe appropriate follow-up testing that is necessary in the resolution of ABO discrepancies (STEP 2)

-Step 2: request new specimen -read forward type first: forward type rxns may not be correct -look at strongest rxns: strong vs weak rxns can provide important clues -any time you encounter a discrepancy of any kind: repeat the test to rule out technical errors, if the results are the same record as discrepant (only O type should be issues until investigate complete), all discrepancies must be investigated and resolved before the correct ABO type can be resulted.

Discuss the genetic interactions of Le genes with ABH and Se genes.

-The Lewis (Le, FUT3)gene is located on chromosome 19 (at 19p13.3), as is the secretor (Se, FUT2) gene at 19q13.3 -There are two alleles at the Lewis locus, Le and the amorph le, and there are two alleles at the secretor locus Se and the amorph se -Interaction of the genes at these two loci: The Le gene must be present for a precursor substance to be converted to Lea, but the Se gene must also be present for conversion to Leb

An individual has inherited the following genes: A/O Se/se h/h le/le Which of the following applies?

-The patient has a strong non-RBC immune antibody that will hemolyze group O RBCs -This patient has the Bombay phenotype, the result of h/h gene inheritance. All Bombay individuals form a potent non-RBC immune anti-H alloantibody that is capable of hemolyzing all red blood cells except those of the Bombay phenotype.

L-fucose and D-galactose have attached to a type-2 precursor chain on a red blood cell. These RBCs will be agglutinated by which reagents?

-anti-B -Ulex europaeus lectin -anti-A,B

Describe in detail each of the following ISBT-recognized Lewis antigens and the antibodies formed against them: BLeb

-anti-BLeb reacts with group B Le(b+) and AB Le(b+) RBCs -person has inherited B genes -alpha-3-D-galactosyltransferase -Leb antigen

An individual with the genes A/O and h/h should have which antibodies in their serum? Choose all that apply

-anti-H, anti-A, anti-B, anti-A,B -An individual with the genes h/h will express the Bombay phenotype regardless of the ABO genes inherited. Individuals with this phenotype naturally form anti-A, anti-B, and anti-A,B antibodies in addition to anti-H.

Describe in detail each of the following ISBT-recognized Lewis antigens and the antibodies formed against them: Leab

-anti-Leab reacts w/ Le(a+b+) and Le(a-b+) RBCs from adults and w/ 90% of cord blood cells -reacts w/ cord blood b/c it will bin to type 2 precursor chains

Describe in detail each of the following ISBT-recognized Lewis antigens and the antibodies formed against them: LebH

-anti-Lebh reacts w/ group O Le(b+) and A2 Le(b+)

A patient's serum sample agglutinates both R2/r' and r"/r RBCs. Which possible antibodies could explain the reactions?

-anti-e -anti-E -anti-c

Compare and contrast the following Rh antigens according to definition, frequency, antigenic reactivity, and recipient/donor compatibility: V, VS

-antigens are found in about 30% of African Americans, rare in Caucasians -in areas w/ high populations of African Americans you would want to screen for this

Lewis antigens

-are not manufactured by erythrocytes -can adsorb onto erythrocyte membranes

resolve/causes of unexpected reactivity in the forward typing

-autoagglutinins/excess protein coating the cells: check patients diagnosis/history (waldenstrons macroglobulinemia, multiple myeloma, recent infusion of high molecular weight volume expander). may need to wash cells (3-4x) and retest. perform DAT w/ saline control -transplantation of out-of-group bone marrow: can be caused by group A bone marrow transplant. check diagnosis/history. possible mf reactivity -acquired B antigen: check patient history/diagnosis (transient, group A can acquire B like antigen). despite reactivity in forward type patients serum will not react w/ autologous red cells (no anti-A) -B(A) phenomenon: autosomal dominant phenotype, weak expression on group B cells. amino acid polymorphisms of B gene are responsible. weak, extra rxn w anti-A <2+ -out-of-group transfusion: possible group B RBC transfuse to group A recipient

describe the major Rhesus (Rh) blood group antigens in terms of biochemical structure and inheritance

-biochemical structure: non-glycosylated, transmembrane, maintain structural integrity of RBC membrane, may have a role in ammonia or CO2 transport -rh antigens are proteins -anti-Rh is the specificity causing the intragroup incompatibles

Describe the biological significance of Lewis antibodies, transitory phenotypes, and correlation with disease states

-biological significance: peptic ulcers, ischemic heart disease, cancer, kidney transplant rejection -lewis antigens have receptors to interact w/ microorganisms expressing a particular lectin: H. pylori is considered to be a major factor causing chronic diseases. -lewis phenotype can change, Lewis antigens disappear during pregnancy

Lewis antibodies

-can be neutralized by soluble Lewis substances -can be variable -can demonstrate in vitro hemolysis - can demonstrate fragile agglutination

Characteristics of the Rh null phenotype include:

-can form alloantibodies to any and all Rh antigens if exposed -shortened RBC survival -compensated hemolytic anemia -stomatocytosis

Acquired B phenomenon

-can occur in the setting of infection by GI bacteria. enteric bacteria can posses deacetylase enzyme capable of converting A antigen to a B like analog -to resolve: rbcs can be tested using a different monoclonal anti-B reagent or acidified (pH 6) human anti-B -human anti-B wont react w/ acquired B antigen.

Describe in detail several causes of ABO discrepancies due to the following: Unexpected reactivity in the reverse typing.

-causes: A2 phenotype w. anti-A1 (common), cold reactive alloantibody (anti-M, anti-P1), old reactive autoantibody (I or Ih), pseudoagglutination due to rouleaux effect (hyperproteinemia), transfusion of incompatible plasma components, recent infusion of IVIG, serum antibody to reagent constituent

Describe in detail several causes of ABO discrepancies due to the following: Unexpected reactivity in the forward typing.

-causes: autoagglutinins/excess protein coating the cells, unwashed cells: plasma proteins, transplantation of out-of-group bone marrow, acquired B antigen, B(A) phenomenon, out-of-group transfusion

Describe in detail several causes of ABO discrepancies due to the following: Weak or missing reactivity in the forward typing.

-causes: weak ABO subgroups, leukemia/malignancy (lost antigens from RBCs), transfusion of group O red cells, bone marrow transplant

Describe in detail several causes of ABO discrepancies due to the following: Weak or missing reactivity in the reverse typing.

-commonly encountered generally due to weak or missing abs. -cause: age related (<4-6 month, elderly), hypogammaglobulinemia, transplantation (immunosuppressed) -resolve: RT incubation and centrifuge again, this may allow abs to enough time to sensitive and form lattice. record on lab workup that you've done this.

Describe the D-- phenotype

-deletions, rare. genetically inherited. ab reacts w/ all E and E proteins -person lacks Cc an Ee -often has unusually strong D antigen expression -"exalted D" -normal RHD genes, and a hybrid RHCE-RHD-RHCE gene in which the Cc Ee proteins are replaced w/ D -Variation: D.. --> evans + Rh: 37 (blood compatible w these people are those who also have a rare type D--)

Compare and contrast the following Rh antigens according to definition, frequency, antigenic reactivity, and recipient/donor compatibility: f (ce)

-expressed when c and e are on the same haplotype (cis position). clinically significant -not a compound antigen, f is single entity -anti-f can cause HDFN and TXRN -compatible w/ someone who has anti-f -genotype matters

Anti-A1 antibodies are

-formed by approximately 1-8% of A2 individuals -are considered to be clincally significant when they react at 37C

Compare and contrast the Lewis system antigens with other blood group systems in terms of: Genetic loci, Inheritance, Antigenic structure, Typical phase of reactivity

-genetic loci: H=FUT1 and locus 19q, Se=FUT2 and locus 19q, Le=FUT3 and locus 19p -inheritance: inheritance of H, Le and Se genes modifies the precursor substance further into the Leb antigen -antigenic structure: soluble lewis anitgens are built onto type 1 glycoproteins (found in saliva/secretions) and on glycosphingolipids (plasma) -reactivity: generally reactive at room temperature and only occasionally at 37 C and AHG phase

Compare and contrast the three mechanisms resulting in 'Weak D' antigen.

-genetic weak D: inheritance of weak D genes, <2% Caucasians, higher in African Americans. d antigens compete, few in #. hard to detect and imbedded in membrane -C trans: position effect, the allele carrying the D is trans to the allele carrying C. D antigen is complete just weak in #. Rh pos blood should fine. ex: *D*ce/d*C*e -Partial D (mosaic): D antigen isn't complete (missing epitopes). cant receive Rh pos blood b/c will form abs to epitopes they're lacking, only receive Rh neg blood.

Saliva from which of the following individuals would neutralize an auto anti-H antibody in the serum of a group A, Le(a-b+) patient?

-group O, Le(a-b+) -Group O individuals have the highest amount of H antigen. The Le(a-b+) phenotype is expressed by secretors. (The Se gene must be present in order to convert Lea substance to Leb substance). Therefore, Group O Le(a-b+) contains the most soluble H substance of the phenotypes listed, and is capable of neutralizing anti-H antibodies.

Recall the frequencies of the four major blood types in the African-American, Asian, Caucasian, and Hispanic populations in the U.S.

-group O: 57% Hispanic -group A: 40% Caucasian -group B: 27% asian -group AB: rare among all races -group O most common, group A is 2nd most common

The serum of a Group O individual will give a negative reaction with which cells? Choose all that apply

-h/h -O/O

Analyze the possible causes of a positive Rh control and why this invalidates the Weak D test.

-if mom is D neg and baby is weak D pos then test for weak D. need for RhIg prophylaxis (if mom is truly rh neg and baby is truly rh pos)

Given the results of ABO typing, correctly identify if a discrepancy exists and if the source is most likely in the forward or reverse type.

-important part of transfusion tests involves detection, recognition, and resolution of ABO discrepancies -discrepant results must be identified an the underlying causes investigated -review practice problems - abo discrepancies lecture

Describe in detail each of the following ISBT-recognized Lewis antigens and the antibodies formed against them: Leb

-inheritance of H, Le, ad Se genes modifies the precursor substance further into Leb antigen -attachment of 2 L-fucose molecules to the basic precursor substance

A person has inherited the Lewis (FUT-3) gene. Lea substance:

-is secreted regardless of secretor status -The formation of Lea substance is the result of Lewis (FUT-3) gene inheritance and is secreted regardless of Secretor (FUT-2) gene inheritance. Therefore, all individuals who inherit the FUT-3 gene will secrete Lea substance regardless of secretor status.

Describe the formation and secretion of Lewis antigens and their adsorption onto the red cell membrane.

-lewis antigens are manufactured by G.I tissue cells and secreted into body fluids -plasma lewis antigens (glycosphingolipids) are then passively absorbed onto the RBC membrane from the plasma, but are not an integral part of the RBC membrane (can elute off) -lewis system referred to as "liquid antigen system"

Compare and contrast the following Rh antigens according to definition, frequency, antigenic reactivity, and recipient/donor compatibility: Cw

-low incidence antigen -antithetical to the high incidence antigen MAR (opposite allele at same locus) -examples of both RBC immune and non-RBC immune -dont screen for cw. usually only seen in HDFN -found in about 2% of Caucasians and very rare in african americans: so rare b/c likelihood of transfusing cw in a unit is very low

List three instances in which the Weak D status of an individual may be determined, and one instance in which Weak D status must be determined.

-may be determined: intended recipients of blood transfusion, expectant mother, neonates -must be determined: blood donors and to confirm the antigen status of a patient who has formed alloanti-D abs.

An Rh-positive person has formed an alloantibody that appears to have anti-D specificity. What could explain this unexpected result?

-missing antigen epitopes -Weak D individuals due to partial D (mosaic) will test positive on the Weak D test. However, these individuals are missing certain epitopes of the D antigen. If transfused with Rh positive blood, they can form alloantibodies to the epitopes they are lacking. Weak D positive individuals who have inherited Weak D genes or express the phenotype due to C in Trans position to D are considered Rh positive and can safely be transfused with Rh positive blood without the risk of alloanti-D stimulation.

Describe in detail the phenotypes capable of forming Anti-Lea and Anti-Leb.

-non-RBC immune (naturally occuring), IgM, -produced w/o exposure to foriegn RBCs. generally produced by patients w/ Le(a-b-) phenotype -anti-Lea is usually stronger than anti-Leb. -anti-Leb can also be produced by Le(a+b-)

The following results were obtained when testing a sample from a 20-year-old, first-time blood donor: Forward type= Anti-A: 0, Anti-B: 0 Reverse type= A1 cells: 0, B cells: 3+ What is the most likely cause of this ABO discrepancy?

-weak subgroup of A (rare) -Although these results are commonly seen in non-group O individuals who are transfused with group O RBCs, this individual is a 20-year old first-time blood donor. If she had recently received a blood transfusion, she would have been deferred for 12 months from the time of blood transfusion. An individual with a known disease process would also likely be deferred. Therefore, although rare, the correct response is a weak subgroup of A. (Possibly Ax or weaker)

as little as ___ mL of D+ blood transfused to a D- induvial is enough to elicit an immune response in the majority of cases

1

the RHD and RHCE genes are located on chromosome ___

1

Which of the following is the most common?

R1r

The Le(a+b+) phenotype is rare in African American and Caucasian adults; however, it can be found in approximately ______________ of adult individuals of Asian ancestry.

10-40%

Mixed field agglutination encountered in ABO grouping with no history of transfusion would most likely be due to

A3 subtype

Why is accurate determination of Rh status crucial for obstetric patients

All Rh negative mothers are potential candidates for RhIg

A patient has formed anti-BLeb antibody, which will react only when both the B antigen (ABO) and the Lewis B antigen (Leb) are found on the red cell in close proximity to each other. However, this patient's antibody screen is negative. What is the most likely reason for this?

All screening cells are group O

the terminal sugar of the B antigen is

D-galactose

The most common Rh haplotype in the African American population is:

Dce

antibodies to antigens with the Rh blood group system are typically RBC-immune with a few exceptions. a few cases of anti-__ and anti-___ have been reported to have been naturally stimulated, w/o a history of pregnancy or transfusion

E, Cw

Of the following, the Rh phenotype expected to react the strongest with the anti-D antibody is:

R2R2

Which genes are linked on the same chromosome?

H, Secretor, Lewis

The anti-A,B antibodies of a group O individual are primarily:

IgG

the anti-B antibody formed by an individual is group A is mostly ___, with approximately ____, IgA and some IgG

IgM, 30%

why are Rh antibodies poor binders (activators) of the classical complement pathway

Rh antigens are spaced too far apart on the RBC (they have to be within 20-40nm of each other)

rh antibodies can drop below detectable levels and can cause both ___ and ___ hemolytic transfusion reactions

acute, delayed

The Lewis antibody most likely to exhibit in vitro hemolysis is:

anti-Lea

The most commonly encountered antibody of the Lewis system is:

anti-Lea

Which of the following is the cause of the acquired B phenomenon?

deacetylation of the A antigen of group A individuals by bacterial enzymes

the lectin that will agglutinate red that express A1 antigen is derived from seeds of the ______ plant.

dolichos biflorus

Which of the following Rh antigens is expressed in the highest frequency among Caucasians in the U.S.?

e

treatment of RBCs with routine enzymes such as ficin, papain, trypsin, and bromelin will:

enhance reactivity with Rh antibodies

abo genes directly encode the production of _____ that will add _____ to basic precursor substances

enzymes, carbohydrates

Rh-mediated hemolytic transfusions reactions, whether caused by primary or secondary immunization usually result in ____ - vascular destruction of immunoglobulin-coated RBCs

extra

Soluble A, B, and H substances are:

glycoproteins

Lewis antibodies and correlation w/ disease states

possible links between chronic H. pylori infections and lewis: -lewis antigens on H. pylori induce pathogenic abs that bind to bacteria and host gastric epithelium. complement fixation and tissue destruction -lewis antigen mimicry can allow H. pylori to evade the immune response. lewis antigens expressed are recognized as "self" -lewis antigens are involved in h. pylori adhesion and colonization to G.I. tissues. this antigen expression is a risk factor for colonization (lectins binding to G.I.)

Lectins are ___ that binds to _____

proteins, carbohydrates

Which of the following is associated with the Acquired B phenomenon?

recent infection with enteric bacteria

Rouleaux in the forward type can be resolved by ___________ ; rouleaux in the reverse type can be resolved by __________________ .

rewashing the cell suspension, saline replacement technique