Adaptive Response Flashcards
Why do self reactive B cell receptors arise?
What happens to them
Random recombination of V gene
Die through apoptosis (-ve selection)
What are the five classes of antibody?
IgG IgA (dimer) IgM (pentamer) IgD IgE
All have different heavy chain
What is most common immunoglobulin?
IgG
What type of infection involves what Ig?
Primary : IgM Secondary: IgG Mucosal: IgA Parasitic: IgE During pregnancy: IgG
Outline path from naive B cell to antibody production
Enter circulation Encounter antigen Activated by CD4 Proliferate Differentiation into plasma cell (class switching) Antibody secretion
What is the important difference between B cell receptors and T cell receptor generation?
T cell repertoire is profoundly influenced by the MHC allotype of an individual through selection
How are T cell receptors selected for in regard to MHC?
Beta chain expression is key stage
Alpha chain then rearrange so for complete TCR
Positive selection removes weak MHC
Negative selection removes too strong MHC
What two types of T cell can arise due to interaction with MHC Class 2?
Th1 or Th2
Dependent on type of antigen. Each secretes different cytokines. Th2 interacts with B cells. Th1 activates macrophage
What are the four main functions of a CD4?
Cytokines secretion
CD8 help
B cell help
Antibody class switching
Outline CD8 action
Cytotoxic activity
Release granules containing perforin, forms pore, and granzyme, lytic enzyme.
Where does antigen presentation occur?
Lymph nodes
What do antibodies do?
Antibodies coat pathogens (opsonise) and target them for phagocytosis
What is difference between affinity and avidity?
Which Ig have highest?
Affinity: strength of binding, highest in IgG
Avidity: overall binding capacity, usually no. of binding sites per molecule = IgM highest
What happens to affinity over repeated infections?
Increased affinity of IgG antibodies due to somatic hypermutation
What is starting antibody before class switching?
IgM
