Immunology Flashcards
Immunoglobulin heavy chains: Domains.
One variable domain and 3-4 constant domains.
Paratope: Definition.
The part of the immunoglobulin molecular that binds the antigen.
Location of genes for immunoglobulin light chains and heavy chains.
Light chains: Chromosomes 2 (κ) and 22 (λ).
Heavy chains: Chromosome 14.
First step in rearrangement of immunoglobulin genes in B cells.
Rearrangement of genes for variable regions: V and J regions of light chains and V, D, and J regions of heavy chains.
Second step in rearrangement of immunoglobulin genes in B cells.
The rearranged sequences of the variable regions are joined to a gene sequence of a constant region of a light chain or heavy chain. The initial heavy-chain constant region is always μ.
Immunoglobulins on mature B cells.
IgM and IgD.
What happens when a helper T cell stimulates a mature B cell?
The B cell proliferates, and each progeny joins its prefabricated variable-gene sequences to a gene for a different heavy chain. This is isotope switching.
Idiotope: Definition.
The part of the (variable region of the) immunoglobulin molecule that can function as an epitope.
Which classes of immunoglobulin have subclasses?
IgG: 4 subclasses.
IgA: 2 subclasses.
Which classes of immunoglobulin can activate complement?
IgG1, IgG3, IgM: Classic pathway.
IgA: Alternate pathway.
Which class of immunoglobulin is the least abundant?
IgE.
Genes for the T-cell receptor:
A. Number.
B. Location.
A. Four genes: α, β, γ, δ.
B. Chromosome 7.
Types of T-cell receptors.
αβ: 95% of T lymphocytes.
γδ: Mostly in mucous membranes and skin.
NK cells:
A. Percentage of circulating lymphocytes.
B. TCR and immunoglobulin.
A. About 10%.
B. Not expressed; genes remain in germline state.
NK cells: Surface markers.
Positive: CD16, CD56, CD57.
Negative: CD3.
NK cells: Purpose of CD16.
As the FcγR, it binds opsonized cells, mediating antigen-dependent cytotoxicity.
NK cells: Functions.
Combating virus-infected cells and tumor cells.
Secreting IFNγ.
Antigen-presenting cells: Immunity-mediating antigens expressed on their surfaces.
All: MHC class II, CD68, lysozyme.
All but monocytes and macrophages: S100, CD1a.
Antigen-presenting cells: Secretion.
Interleukin 1.
Chemokine that attracts neutrophils.
Interleukin 8 (among others).
How basophils and mast cells come to release the contents of their granules.
They use their Fcε to bind IgE, the cross-linking of which promotes degranulation.
Cytokines that stimulate eosinophils.
IL-4 stimulates production of IgE.
IL-5 attracts eosinophils.
Both interleukins are secreted by Th2 cells.
Charcot-Leyden crystals:
A. Origin.
B. Function.
A. Degranulation of eosinophils.
B. They have lysophospholipase activity.
Complement: Final common pathway.
Formation of C5b6789, the membrane-attack complex.