Glossary Ch 4

Question 1

Adaptive immunity

Answer 1

A type of resistance that is characterized by specificity for each individual pathogen, or microbial agent, and the ability to remember a prior exposure, which results in an increased response to that pathogen upon repeated exposure

Question 2

Allelic exclusion

Answer 2

The selection of an allele on one chromosome only

Question 3

Antigen-dependent phase

Answer 3

The final phase of B-cell development, which occurs when a B cell is stimulated by an antigen and undergoes transformation to a blast stage, resulting in the formation of memory cells and antibody-secreting plasma sells

Question 4

Antigen-independent phase

Answer 4

The first phase of B-cell development in the bone marrow, which results in mature B cells that have not yet been exposed to antigen

Question 5

Cell flow cytometry

Answer 5

An automated system for identifying cells based on the scattering of light as cells flow single file through a laser beam

Question 6

Cell-mediated immunity

Answer 6

A type of immunity in which T cells produce cytokines that help to regulate both the innate and adaptive immune response

Question 7

Central tolerance

Answer 7

Destruction of potentially self-reactive T and B cells as they mature in either the thymus or the bone marrow

Question 8

Chemokines

Answer 8

A large family of homologous cytokines that promote migration of WBCs through chemotaxis

Question 9

Clonal deletion

Answer 9

The process of elimination of clones of lymphocytes that would be capable of an autoimmune disease

Question 10

Cytotoxic cells T cells

Answer 10

T cells that bear the CD8 marker; They kill virus-infected cells and tumor cells by triggering apoptosis

Question 11

Double-negative (DN) tymocytes

Answer 11

Stage in the development of T cells when neither CD4 nor CD8 is expressed

Question 12

Double-positive (DP) tymocytes

Answer 12

Stage in the development of T cells when when both CD4 and CD 8 antigens are expressed

Question 13

Humoral immunity

Answer 13

Protection from disease resulting from substances in the serum (e.g., antibodies)

Question 14

Immature B cells

Answer 14

A phase in the growth of B cells characterized by the appearance of complete IgM antibody molecules on the cells surface

Question 15

MHC restriction

Answer 15

The selection of thymocytes that will only interact with the MHC antigens found on the cells

Question 16

Negative selection

Answer 16

The process by which T cells that can respond to self-antigen are destroyed in the thymus

Question 17

Plasma cell

Answer 17

A differentiated B cell that actively secretes antibody

Question 18

Positive selection

Answer 18

The process of selecting immature T lymphocytes for survival on the basis of expression of high levels of CD3 and the ability to respond to self-MHC antigens

Question 19

Pre-B cells

Answer 19

The statge of development of a B cell where the heavy-chain part of the molecule is present

Question 20

Pro-B cells

Answer 20

A stage in B-cell development in which rearrangement of the genes that code for the heavy-chain region of an antibody molecule occur

Question 21

Surrogate light chain

Answer 21

Two short polypeptide chains noncovalently associated with each other that appear before actual light chains are formed by a developing B cells

Question 22

T-dependent antigens

Answer 22

An antigen that requires T-cell help in order for B cells to respond

Question 23

T-helper (Th) cells

Answer 23

Lymphocytes that express the CD4 antigen; their function is to provide help to B cells in recognizing foreign antigen and producing antibody to it

Question 24

T-independent antigens

Answer 24

An antigen that is able to elecit antibody formation in the absence of T cells

Question 25

Tymocytes

Answer 25

Immature lymphocyte, found in the thymus, that undergoes differentiation to become a mature T cells

Question 26

Variable regions

Answer 26

The amino-terminated region of an immunogloblulin molecule (half of a light chain or quarter of a heavy chain) that has a unique amino acid sequence for each different immunoglobulin molecule; this part is responsible for the specificity of a particular immunoglobulin molecule