Immunology Exam II: Quick

IgG possesses ____ binding sites for antigen, and the T-cell receptor possesses _____ binding sites for antigen.

-2 -1

An immunoglobulin molecule contains...?

-2 identical light chains

The class-specific [isotype] determinants [or regions] of immunoglobulins are associated with?

-H chains

​Discuss​ ​how​ ​T-cell​ ​receptors​ ​differ​ ​from​ ​immunoglobulins​ ​in​ ​the​ ​way​ that​ ​they​ ​recognize antigen.​ ​Use​ ​the​ ​following​ ​terms​ ​in​ ​your​ ​answer:​ peptides,​ ​antigen-presenting​ ​cells,​ ​MHC molecules,​ ​and​ ​antigen-binding​ sites.​

-T-cell receptors: only bind to peptides. They cannot bind directly to a free antigen so they use antigen-presenting cells to present the antigen peptides and interact with MHC molecules, type I and II. They only have one antigen-binding site -Immunoglobulins: can bind to peptides, lipids, carbohydrates, and intact proteins. they can bind directly to the free antigen. They have at least 2 antigen-binding sites. IgA has 4 when dimerized and IgM has 10 when in the form of a pentamer

What​ ​is​ ​the​ ​difference​ ​between​ ​TI​ ​(thymus​ ​independent)​ ​antigens​ ​and​ ​TD​ ​(Thymus​ ​dependent) antigens?​ ​Describe​ ​that​ ​different​ ​types​ ​of​ ​TI​ ​antigens​ ​with​ ​an​ ​example​ ​each.​ ​How​ ​are​ ​they recognized​ ​(how​ ​different​ ​signaling​ ​pathways​ ​that​ ​are​ ​used​ ​in​ ​case​ ​of​ ​each​ ​antigen)?​ ​How​ ​are​ ​TD antigen​ ​recognized?

-TI have two types of antigens: Type 1 LPS of gram negative activate immature as well as mature B2 cells, and only IgM are produced Type 2 Repetitive density epitopes of protein or carbohydrates activate mature B1 cells only mostly IgM and some IgG produced. -TD antigens arrive to secondary Lymph tissue to T cell area, APC activates CD4 T cells circulates naive B cells will enter T cell area via HEV

What is the hallmark of transition between an immature B cell and a mature (naïve) B cell?

-migration from the bone marrow

Match the following. _______Allows B cells to switch from producing membrane-bound immunoglobulin to soluble forms following exposure to antigen. _______Ensures that a particular B cell expresses only one type of immunoglobulin with respect to its antigen binding specificity. ______Introduces point mutations preferentially into CDR1, CDR2, and CDR3 of the antigen binding site, post-antigen encounter of only B cells. _______Introduces genetic variation into a coding joint of recombined gene segments for B cell Ig genes. A. Allelic Exclusion B. Somatic Hypermutation C. Post transcriptional Modification D. Somatic Recombination

1. C 2. A 3. B 4. D

Indicate which of the following statements concerning memory B cells are true (T) and which are false (F).: 1. _____T cells and B cells recognize the same types of antigens. 2. _____ T cells and B cells require MHC molecules for the recognition of peptide antigens. 3. ______ T cells require an accessory cell called an antigen-presenting cell, which bears MHC molecules on its surface. 4. ______T-cell receptor and immunoglobulin genes are encoded on the MHC. 5.______The T-cell receptor has structural similarity to an immunoglobulin Fab fragment.

1. F 2. F 3. T 4. F 5.T

Indicate which of the following statements concerning memory B cells are true (T) and which are false (F).: 1. ____Memory B cells are derived from germinal center B cells as immune responses subside. 2. _____ Memory B cells have long life-spans. 3. ______Memory B cells possess high-affinity antigen receptors as a consequence of affinity maturation. 4. ______ Memory B cells have more stringent requirements for activation than naive B cells do. 5. _______ Memory B cells express only IgM and retain the capacity to switch to the most beneficial isotype during secondary responses.

1. T 2. T 3. T 4. F 5. T

Which immunoglobulin isotypes ( IgM,IgG, IgG1, IgG2, IgG3, IgG4,IgA,IgE) participate in (a) neutralization, (b) opsonization, (c) sensitization for killing NK cells, (d) sensitization of mast cells, (e) activation of complement? Which isotypes (f) are transported across epithelium, (g) are transported across the placenta, (h) diffuse into extravascular sites?

A) IgA and IgG 1,2,3 and 4- function in neutralization of toxin and venoms B) Ig G1 and Ig G3 C) IgG 1 and 3- sensitization for killing of NK cells D) IgE- sensitization of mast cells E) IgM and IgG 1 and 3- activation of complement F) IgA (dimer) G) IgG 1 and 3- prenatal immunoglobulin H) Ig G 1,2,3,4 and Ig A (monomer) is in cardiovascular tissue, *IgM, IgG, IgA most common immunoglobulin in blood

Which of the following cell types does not express MHC class I? a. erythrocyte b. hepatocyte c. lymphocyte d. dendritic cell e. neutrophil

A.

A.​ ​What​ ​are​ ​the​ ​characteristics​ ​features​ ​of​ ​the​ ​peptides​ ​binding​ ​to​ ​MHC​ Class​ ​I​ ​and​ ​MHC​ ​class​ ​II molecules? ​ ​​ B.​ ​How​ ​does​ ​this​ ​relatively​ ​small​ number​ ​of​ ​MHC​ ​molecules​ ​have​ ​the​ ​potential​ ​to​ ​bind​ ​the​ ​huge number​ ​of​ antigenic​ ​peptides​ ​encountered​ ​in​ ​the​ ​environment?

A. : Peptides that bind to the MHC 1 molecule are those that will eventually be presented to the CD8 receptor of a T cell. These antigens usually are viral, and are released inside of the cell where a proteasome will degrade the viral protein into peptides. These peptides will then be delivered to the MHC 1 and be presented to the outside of the cell. Peptides that bind to MHC 2 molecules are those that will be presented to CD4 receptor of either Th1 cell or Th2 cell. These antigens are engulfed whole by the cell, where it will be degraded in the phagolysosome of the APC into peptides. A MHC 2 molecule will be emerged and the peptide will bind and be presented on the outside of the cell. B: MHC molecules have degenerate binding specificity, which means that one MHC molecule is able to bind a wide range of peptides of different sequence.

Pathogens​ ​that​ ​infect​ ​the​ ​human​ ​body​ ​replicate​ ​either​ ​insides​ ​cells​ ​(such​ as​ ​viruses)​ ​or extracellularly,​ ​in​ ​the​ ​blood​ ​or​ ​in​ ​the​ ​extracellular​ ​spaces​ ​in​ tissues. A.​ ​Identify​ ​(i)​ ​the​ ​class​ ​of​ ​T​ ​cells​ ​that​ ​are​ ​stimulated​ ​by​ ​intracellular​ ​pathogens, ​ ​(ii)​ ​their co-receptor,​ ​(iii)​ ​the​ ​MHC​ ​molecule​ ​used​ ​for​ ​recognition​ ​of​ ​antigen​ ​and​ ​(iv)​ ​the​ ​T-cell​ ​effector function.​ ​​ B. Repeat this for the classes of T cells that are stimulated by extracellular pathogens. For the purpose of this question, count those pathogens that can survive and live inside intracellular vesicles after being take up by macrophages as extracellular pathogens

A.: i. T cells that are stimulated by intracellular pathogens are cytotoxic T cells ii. their co-receptors are CD8 iii. CD8 interacts with MHC I molecules on APC's iv. Cytotoxic T cells kill cells infected with a pathogen whose peptides are shown on MHC I molecules, stopping the pathogen from spreading and infecting neighboring cells B.: i. T cells that are stimulated y extracellular pathogens are helper T cells which have 2 classes Th1 and Th2. ii. Helper t cells have CD4 co-receptors iii. these t cells interact with MHC II molecules on APC's iv. Th1 cells activate macrophages which show the pathogen's peptides on MHC II molecules on their surface. Th2 cells activate B cells which show antigen-derived peptides on MHC II molecules causing the B cells to differentiate into plasma cells. The antibodies released remove the extracellular pathogen.

Which of the following is mismatched? a. CD8 T cell: cytotoxicity b. CD4 TH2 cell: cytotoxicity c. CD4 TH1 cell: macrophage activation d. CD4 TH2 cell: B-cell activation e. CD4 TH2 cell: HIV infection

B.

A child has no detectable T or B cells. This immunodeficiency is most probably the result of a defect in: a. the thymus b. the bursal equivalent c. T cell-B cell interaction d. stem cells originating in the bone marrow

D.

Antigen-presenting cells that activate helper T-cells must express which one of the following on their surfaces? a. IgE b. gamma interferon c. class I MHC antigens d. class II MHC antigen

D.

In B cells, transport of immunoglobulin to the membrane is dependent on association with two invariant proteins, Igα and Igβ. Which of the following invariant proteins provide this function for this function for the T-cell receptor in T cells? a. CD3 γ b. CD3 δ c. CD3 d. ζ e. All of the above

E.

Which of the following characterizes the B-1 cells that develop prenatally? A. they lack N nucleotides [no junctional diversity] B. they possess polyspecificity for bacterial polysacc. antigens C. they arise early in embryonic development preceding the development of the majority subset of B cells D. have restricted V-region E. All of the above

E.

What is the most important immunological advice you could give to a new mother to keep the infant healthy during the first month and why?

I would advise the mother to breastfeed. Breast milk provides the baby with vitamins, proteins, and fats. Additionally, the babies get IgA from the breast milk which fight against any present pathogens in the mucosa and lowers their risk for allergies and asthma. IgA travels to the baby's gut ( via passive immunity).

Which of the following explains why immunity to influenza may appear to be relatively short-lived?

New influenza variants are able to escape prior immunity regularly

The double diffusion method allows for disease identification and diagnosis and is an application of what immunological technique? a. agglutination b.precipitation c. immunoassay d. fluorescent antibody test e. complement fixation

b.

What is the role of class II MHC proteins on donor cells in graft rejection? a. They are the receptors for interleukin-2, which is produced by macrophages when they attack the donor cells b. They are recognized by helper T cells, which then activate cytotoxic cells to kill the donor cells. c. They induce the production of blocking antibodies that protect graft d. They induce IgE which mediates graft rejection

b.

Based on the principles of MHC-restricted recognition, Homer Simpson's cytotoxic T-cells specific for measles virus should be able to kill virus-infected cells derived from: a. his father Abe b. his daughter Lisa c. both d. neither

c.

Owing to the location of the δ chain locus of the T-cell receptor on chromosome 14, if the _______-chain locus rearranges by somatic recombination, then the δ-chain locus is _______: a. α: also rearranged b. α: deleted c. α: transcribed d. β: deleted e. γ: also rearranged

d.