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Review on B cells

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Immunology Block 2

Pregunta 1 de 21

1

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

Selecciona una de las siguientes respuestas posibles:

  • VH

  • VL

  • CH 2

  • CL

Explicación

Pregunta 2 de 21

1

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

Selecciona uno de los siguientes:

  • VERDADERO
  • FALSO

Explicación

Pregunta 3 de 21

1

Antigen Binding site

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 4 de 21

1

Ig Determinants

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 5 de 21

1

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

Selecciona uno de los siguientes:

  • VERDADERO
  • FALSO

Explicación

Pregunta 6 de 21

1

Regarding different classes of Ig a

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 7 de 21

1

Regarding Pro-B cell all are true except?

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 8 de 21

1

Regarding Pre-B cell

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 9 de 21

1

Immature B cell - all are true except

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 10 de 21

1

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

Selecciona uno de los siguientes:

  • VERDADERO
  • FALSO

Explicación

Pregunta 11 de 21

1

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

Selecciona uno de los siguientes:

  • VERDADERO
  • FALSO

Explicación

Pregunta 12 de 21

1

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

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 13 de 21

1

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

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 14 de 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

Selecciona uno de los siguientes:

  • VERDADERO
  • FALSO

Explicación

Pregunta 15 de 21

1

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

Selecciona uno de los siguientes:

  • VERDADERO
  • FALSO

Explicación

Pregunta 16 de 21

1

Endogenous pathway MHC I and Exogenous pathway MHC II

Selecciona uno de los siguientes:

  • VERDADERO
  • FALSO

Explicación

Pregunta 17 de 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

Selecciona uno de los siguientes:

  • VERDADERO
  • FALSO

Explicación

Pregunta 18 de 21

1

T cell recognize non linear and conformational determinants

Selecciona uno de los siguientes:

  • VERDADERO
  • FALSO

Explicación

Pregunta 19 de 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

Selecciona uno de los siguientes:

  • VERDADERO
  • FALSO

Explicación

Pregunta 20 de 21

1

Viral proteins interfere with MHC I

Selecciona una de las siguientes respuestas posibles:

  • Inhibit peptide transport

  • Inhibit peptide loading

  • Cause MHC I degradation

  • all of the above

  • none of the above

Explicación

Pregunta 21 de 21

1

Intracellular bacteria evade MHC II by

Selecciona una de las siguientes respuestas posibles:

  • Escape endosomes

  • Neutralize endosome acidification

  • Block fusion with lysosomes

  • Sequesters MHC II molecules after vesicle fusion

  • All of the above

Explicación

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