Immunohemotology ABO/Rh

Rh

*second most important blood group system -Rh = antigens that are on proteins D = Rh positive = Rh(D) positive -D is dominant over d --> (+) as DD and Dd *you dont make antibody to RhD if youre Rh(D)- and you become immunized with Rh(D)+

Define heterophile antibody, and identify a common disease in which one type is increased enough to be useful diagnostically.

-Antibodies to one antigen can bind to another (aka cross-reactive antibodies) ex: ab in a patient with infectious mononucleosis --> cross reacts well with horse RBC ex: ab people with syphilis make --> cross reacts with phospholipids with beef heart *gives us a cheap and quick reaction to test

Explain the ABO antigen situation in a person of Bombay blood type, and the consequences of a transfusion of non-Bombay blood into such a patient.

-Bombay people would type as O even though theyre not O -can only transfer bombay blood

For persons of the A, B, AB and O blood groups, give the following data: most and least common groups; red cell antigens; specificities of the ABO antibodies in their plasma; safe donors to that type; safe recipients of blood from that type; possible genotypes.

-Red cells dont carry MHC antigens in humans --> antigens are much less polymorphic in the population -platelets do bear HLA (Class I) --> can cause alloimmunization problem GROUP O -defined by H antigen -"amorph": doesnt code for working transferase --> group O only have basic Core (H antigen) -best for blood donors = O- GROUP A -defined by A antigen GROUP B -defined by B antigen GROUP AB -have both A and B antigens on the red cells; 1/2 have circle 1/2 have square -rarest BOMBAY: people dont have the H at the end --> A and B and O are all foreign -truncated version of the H antigen *need the H substance to add on the final sugar (square or circle) that defines which group you are -everyone has H antigen

Define the crossmatch, and explain why it is important. Explain how red cells are destroyed following a mismatched transfusion, and why this may be devastating to the recipient

-prior to transfusion, recipients are typed for ABO and Rh -> screen for expected and unexpected antibodies *must be compatible at ABO and Rh MAJOR CROSSMATCH: worst case scenario --> generalized complement mediated hemolysis --> free hemoglobin deposits in the kidney --> acute renal failure *crossmatch is a test where plasma from prospective recipient is mixed with RBC for donor -no hemolysis/agglutination : compatible O- = universal donor AB+ = universal recipient

Explain the situation in which ABO hemolytic disease of the newborn can occur.

Baby is RhD+ and mom is RhD-

Compare and contrast the techniques of the direct and indirect antiglobulin tests and the questions they are designed to answer.

COOMBS TEST: uses antibody against human Ig to detect human Ig on surface of RBC [direct] or plasma [indirect] DIRECT -is there Ab already on the cells? -rinse off the cells, add antiglobulin *detects cells that were coated with Ab in vivo INDIRECT -is there unexpected Ab to red cell antigens in the plasma of the recipient -take RBC, add plasma of donor, rinse cells, add antiglobulin -->if agglutinate there is Ab to them in the plasma (antiglobulin alone wont react with red cells)

Name the antibody class of most ABO isohemagglutinins.

Isohemagglutinins: antigens to the ABO groups that we dont have in our RBC -we are all exposed to these sugars (A, B, O) --> and we make Ab to the sugars that are foreign to us -ex: A blood will make Ab to B but not A *dont make antibody to O -Iso are of the IgM class -If anti-b: can be AA or AO

In Hemolytic Disease of the Newborn, explain: a. The consequences of severe hemolysis in the newborn. b. The way in which the mother becomes sensitized. c. The class of antibody to Rh(D) the mother makes. d. The consequences of sensitization to subsequent fetuses. e. The role of Rh-immune globulin.

aka erythroblastosis fetalis -occurs in RhD+ babies of RhD- moms -in last trimester and delivery, RBC from baby get into mom's circulation --> mom will make anti RhD -subsequent pregnancy w/ another RhD+ baby --> mom's Ab (from 1st pregnancy) can cross placent and destroy the fetus's RBC *w/ each pregnancy, response will increase -fetus will be born jaundiced --> dangerous because bilirubin can cross blood brain barrier and damage basal ganglia --> cerebral palsy or death PREVENTIBLE -at time of first (+) baby: if mom is given IgG ab to RhD --> Ab will opsonize RBC --> destroy before change to immunize her *she must recieve Rh IgG each time *perhaps give mom a shot before 3rd trimester to prevent immunization of bleeds