Lymphocytes.csv

complimentarity-determining region; another name for variable region

recombination occurs before antigen exposer & involves V(D)J gene segments; hypermutation is a secondary response that occurs after antigen exposure and involves the introduction of point mutations into the variable region of the both chains; hypermutation acts primarily on rearranged V regions that are being actively transcribed (enzyme AID requires single-stranded DNA); hypermutation requires T-cell stimulation

dendritic cells of the skin

supportive epithelial cells found in lymphatic tissue; protect T lymphoblasts & macrophages in the thymus via a network of long processes; produce supportive reticular fibers in other lymphatic tissue

distinct structural features found in the medulla of the thymus; made of concentric circles of epithelial cells; filled with keratin & sometimes calcified; function unclear

arterioles & capillaries in the cortex of the thymus are surrounded by cells with tight junctions; antigens cannot enter into thymus; no barrier in medulla - allows T lymphocytes to exit

periarticular lymphatic sheath; surrounds splenic arteries and arterioles; makes up white pulp; T cells surround the blood vessels; B cells within nodules

surrounds white pulp; contains many blood sinuses & loose lymphoid tissue & macrophages & lymphocytes

"defined by splenic cords (reticular cells & macrophages & lymphocytes & plasma cells) and venous sinusoids; sinusoids have unusual ""fenestrated"" epithelium (stave cells)"

the affinity of B cells for a specific antigen increases over time (with secondary and tertiary responses); largely due to somatic hypermutation introducing variability into B cell population; cells with affinity-enhancing mutations can survive and compete for antigen more effectively

all B cells are originally IgM or IgD; irreversible DNA recombination to pair rearranged variable region with different C regions occurs after antigen exposure; stimulated by external signals such as cytokines (mostly T-cell derived)

terminal deoxytransferase; adds random nucleotides to the signal joint after somatic recombination to generate additional diversity

a molecule that promotes multimerization of antibodies (especially IgM multimers and IgA dimers)

successful rearrangement on one chromosome leads to a shutdown of the rearrangemet process on the homologous chromosome; leads to expression of a single receptor on the B cell surface; may prevent autoimmunity & ensure high affinity

developing B cells that react with self antigen are retained in the bone marrow; B cells that react with self antigen after entering circulation are induced to enter an anergic state

do not require co-stimulation by T cells; occur in response to LPS or bacterial DNA or other motifs; 2 kinds; limited by lack of affinity maturation & memory

involves adding material to a vaccine that is not the antigen against which the vaccine is directed; allows T cells to activate B cells; absence prevents B cell presentation of peptides to T cells

the specific combination of MHC alleles found on a single chromosome

MHC molecule that inhibits NK killing action on self cells; absence suggests infection and leads to cell destruction by NK cells

major cell signaling receptor on T cells

transcription factor that causes certain genes to be expressed in the thymus that would not normally be expressed; allows T cells to recognize self peptides that are found elsewhere in the body

co-stimulatory molecules; B7 on antigen presenting cells interacts with CD28 on T cells to activate T cells; required for IL-2 release from T cells which leads to T cell differentiation and proliferation

Th = subset of CD4+ T cells; Th1 cells primarily activate macrophages; Th2 cells primarily act on B cells

regulatory T cells;CD4+ and CD25+ cells that express FOXP3 (transcription factor); interact directly with cells or release cytokines