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Review on B cells

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Immunology Block 2

Question 1 of 21

1

All of the following are part of Fab region of Ig except?

Select one of the following:

  • VH

  • VL

  • CH 2

  • CL

Explanation

Question 2 of 21

1

VH and VL determines the idiotype and CH2 and CH3 determine the isotype of Ig

Select one of the following:

  • True
  • False

Explanation

Question 3 of 21

1

Antigen Binding site

Select one of the following:

  • Specificity is determined by hypervariable regions within the variable domain

  • Each variable region has 3 hypervariable regions called complementary determining regions (CDRs)

  • An antigen binding site is composed of 3 light chain CDRs and 3 heavy chain CDRs

  • All of the above are true

  • None of the above

Explanation

Question 4 of 21

1

Ig Determinants

Select one of the following:

  • Isotypic : constant domain, present in all individuals of a species

  • Allotypic: constant domain; different alleles within a species

  • Idotypic: antigen binding site

  • all of the above are true

  • 1&2 are true

Explanation

Question 5 of 21

1

Antibodies interact with molecules by the Fc receptors (constant region)

Select one of the following:

  • True
  • False

Explanation

Question 6 of 21

1

Regarding different classes of Ig a

Select one of the following:

  • IgG - Monomer - circulating - Most abundant in serum - crosses transplacentally via brambell receptor

  • IgM - Pentamer - Surface of B cells or circulating - Ag receptor on B cell - First class of Ab released by B cells during primary response

  • IgA - Monomer - Surface of B cells - Important for B cell activation - Co-expressed with IgM on B cells due to differential RNA splicing

  • IgD - circulating monomer, secreted dimer - circulating in plasma or secreted in saliva ,tears, milk etc - protects mucosal surfaces

  • IgE - Monomer - circulating or cell bound - found in mast cells and basophils - High affinity IgE receptors binds in the absence of Ag

  • All are correct

  • 1,2,5 are correct

  • 3,4 are correct

  • All are wrong

Explanation

Question 7 of 21

1

Regarding Pro-B cell all are true except?

Select one of the following:

  • No Ig is expressed

  • Recombination Signal Sequences (RSS) & 12/23 rule regulate arrangement & ensure that proper joining occurs: D-J --> V-DJ

  • RAG1/RAG2 recognised and binds to Il-7R

  • Palindromic nucleotide addition at hairpin loop formation by DNA polymerase

  • Non-template nucleotide addition at hairpin loop formation by TdT

Explanation

Question 8 of 21

1

Regarding Pre-B cell

Select one of the following:

  • IgM expressed

  • Allelic Exclusion: RAG1/RAG2 is repressed to stop VDJ rearrangement of H locus

  • RAG1/RAG2 is re-expressed for VJ rearrangement - Somatic Recombination - of each daughter cell's L chain

  • Kappa light chain recombines 1st

  • all of the above are correct

Explanation

Question 9 of 21

1

Immature B cell - all are true except

Select one of the following:

  • IgG expressed

  • Negative Selection for Tolerance - Immature B cell with no self reaction will continue on to maturity and leave the bone marrow

  • Light chain rearranges for a chance to make BCR with new specificity

  • Immature B cell binds multivalent self-antigen and fails receptor editing --> Clonal deletion (apoptosis)

  • mmature B cells bind soluble self-antigen --> Clonal anergy

Explanation

Question 10 of 21

1

Mature B cell express IgM + IgD due to differential RNA splicing

Select one of the following:

  • True
  • False

Explanation

Question 11 of 21

1

CD21 co-receptor binds Fc of Ig (ITIM) - positive co-receptor --> activation
FcyR binds to C3d - negative co-receptor --> no activation

Select one of the following:

  • True
  • False

Explanation

Question 12 of 21

1

Following is the sequence of events 1st T_B cell interaction - all of the following are true except?

Select one of the following:

  • Antigen activated B cell (APC) migrates toward T-B boundary and present antigen by MHC II to CD4+ Helper T cell

  • CD40 activates T Helper to express CD40-L and cytokines

  • CD40-CD40-L bind and T Helper releases cytokines toward B cell

  • Mutated CD40-L results in X-Linked agammaglobulinemia

  • Proliferation of activated B cell to form germinal centers (Clonal expansion)

  • AID (Activation Induced Deaminase) inserts point mutations in the variable regions of BCR for diversification of BCR

Explanation

Question 13 of 21

1

All of the following regarding 2nd T-B cell interaction are true except?

Select one of the following:

  • Class/Isotypic Switching : The constant region of the heavy chain undergoes change of Ig Isotype but the selected variable region stays the same maintaining antigenic specificity and affinity

  • Isotype is determined by cytokines released from Helper T cell

  • Enables the same assembled Vh exon to be associated with different CH genes in the course of an immune response thus increasing the divrsity of Ig function

  • Il-4 secreting T cell stimulate Plasma cell production and Il-10 secreting T cell stimulate memory B cell production

Explanation

Question 14 of 21

1

Thymus independent response the antigens are polysaccharides and the antibody made is always IgM because there is no class switching, no affinity maturation and no memory cell formation

Select one of the following:

  • True
  • False

Explanation

Question 15 of 21

1

MHC Class I is expressed on the surface of all nucleated cells including RBC

Select one of the following:

  • True
  • False

Explanation

Question 16 of 21

1

Endogenous pathway MHC I and Exogenous pathway MHC II

Select one of the following:

  • True
  • False

Explanation

Question 17 of 21

1

Antign processing is proteolytic deradation of proteins into peptides of a suitable size for binding to MHC
Antigen Presentation - actual display of the processed peptide bound to MHC molecules on the surgace of an APC or target cell

Select one of the following:

  • True
  • False

Explanation

Question 18 of 21

1

T cell recognize non linear and conformational determinants

Select one of the following:

  • True
  • False

Explanation

Question 19 of 21

1

Dendritic cells are exception to the rule - Cross presentation allows exogenous proteins to be presented on MHC I and endogenous proteins to be presented by MHC II by autophagy

Select one of the following:

  • True
  • False

Explanation

Question 20 of 21

1

Viral proteins interfere with MHC I

Select one of the following:

  • Inhibit peptide transport

  • Inhibit peptide loading

  • Cause MHC I degradation

  • all of the above

  • none of the above

Explanation

Question 21 of 21

1

Intracellular bacteria evade MHC II by

Select one of the following:

  • Escape endosomes

  • Neutralize endosome acidification

  • Block fusion with lysosomes

  • Sequesters MHC II molecules after vesicle fusion

  • All of the above

Explanation

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