1-4 Clonal Selection of Antigen-Specific Lymphocytes

Question 1

B cell antigen receptor

Answer 1

The complex of membrane immunoglobulin that recognizes antigen and a heterodimer of Igα and Igβ that signals antigen recognition in B lymphocytes.

Question 2

Clonal Deletion

Answer 2

Elimination of potentially self-reactive lymphocytes. Immature lymphocytes undergo programmed cell death after binding to antigen; in this way, cells bearing receptors that recognize self are deleted before they are capable of participating in immune responses. This is a major mechanism of immune tolerance.

Question 3

Clonal Expansion

Answer 3

The selective proliferation of mature naive lymphocytes that encounter antigen. Only those lymphocytes berating receptors specifically recognizing antigen are activated to proliferate and differentiate into effector cells.

Question 4

Clonal Selection

Answer 4

The process whereby potentially self-reactive lymphocytes are eliminated during ontogeny whereas mature lymphocytes recognizing non-self antigens are selectively expanded.

Question 5

Constant region (C region)

Answer 5

Region of a lymphocyte receptor for antigen that does not participate in antigen binding and does not vary between cells of different antigen specificities.

Question 6

Heavy Chain

Answer 6

The immunoglobulin heavy chains are the larger of the two kinds of polypeptide chains in the immunoglobulin molecule. Each light chain has a variable region contributing to the antigen-binding site, and a constant region that mediates the effector function of the molecule.

Question 7

Immune Tolerance

Answer 7

Non-responsiveness of the adaptive immune system to antigen.

Question 8

Immunoglobulin superfamily

Answer 8

Family of proteins containing at least one immunoglobulin-like domain and for which the Ig-like domains is a major structural element.

Question 9

Light Chain

Answer 9

The immunoglobulin light chains are the smaller of the two kinds of chains in the immunoglobulin molecule. Each has a variable region contributing to the antigen-binding site, and a constant region containing a cysteine by which it makes a disulfide bond with the constant region of the heavy chain.

Question 10

T cell receptor (TCR)

Answer 10

The complex of variable chains wherby T cells recognize antigen and signaling chains whereby antigen recognition is signaled to the cell interior.

Question 11

Variable Region (V region)

Answer 11

Region of a lymphocyte receptor for antigen that participates in antigen binding and varies between cells of different antigen specificities.