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Immunology Block 2

Description

Review on B cells
ivenkat
Quiz by ivenkat, updated more than 1 year ago
ivenkat
Created by ivenkat over 9 years ago
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Resource summary

Question 1

Question
All of the following are part of Fab region of Ig except?
Answer
  • VH
  • VL
  • CH 2
  • CL

Question 2

Question
VH and VL determines the idiotype and CH2 and CH3 determine the isotype of Ig
Answer
  • True
  • False

Question 3

Question
Antigen Binding site
Answer
  • 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

Question 4

Question
Ig Determinants
Answer
  • 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

Question 5

Question
Antibodies interact with molecules by the Fc receptors (constant region)
Answer
  • True
  • False

Question 6

Question
Regarding different classes of Ig a
Answer
  • 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

Question 7

Question
Regarding Pro-B cell all are true except?
Answer
  • 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

Question 8

Question
Regarding Pre-B cell
Answer
  • 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

Question 9

Question
Immature B cell - all are true except
Answer
  • 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

Question 10

Question
Mature B cell express IgM + IgD due to differential RNA splicing
Answer
  • True
  • False

Question 11

Question
CD21 co-receptor binds Fc of Ig (ITIM) - positive co-receptor --> activation FcyR binds to C3d - negative co-receptor --> no activation
Answer
  • True
  • False

Question 12

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

Question 13

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

Question 14

Question
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
Answer
  • True
  • False

Question 15

Question
MHC Class I is expressed on the surface of all nucleated cells including RBC
Answer
  • True
  • False

Question 16

Question
Endogenous pathway MHC I and Exogenous pathway MHC II
Answer
  • True
  • False

Question 17

Question
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
Answer
  • True
  • False

Question 18

Question
T cell recognize non linear and conformational determinants
Answer
  • True
  • False

Question 19

Question
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
Answer
  • True
  • False

Question 20

Question
Viral proteins interfere with MHC I
Answer
  • Inhibit peptide transport
  • Inhibit peptide loading
  • Cause MHC I degradation
  • all of the above
  • none of the above

Question 21

Question
Intracellular bacteria evade MHC II by
Answer
  • Escape endosomes
  • Neutralize endosome acidification
  • Block fusion with lysosomes
  • Sequesters MHC II molecules after vesicle fusion
  • All of the above
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