Lymphocyte Function Flashcards
what are all lymphocytes?
antigen specific
how is speciality achieved?
antigen receptor on cell surface
what are the B cell receptors?
cell surface antibody
what are the T cell receptors?
T cell receptor (TCR)
what are cells of the same specificity?
clone
what synthesises and secretes immunoglobulins?
B cells
what do B lymphocytes need to be secreted?
they need to be activated and differentiate into plasma cells
what is the antigen receptor on B cell?
the antibody that the B cell is programmed to make
what happens if an antigen receptor on a B cell binds to a specific antigen?
stimulus for B cells to divide and produce clonal expansion and differentiate
What are antibodies encoded by?
multiple gene segments
what are VH domains coded by?
3 gene segments:
- variable
- diversity
- joining
what are VL domains coded by?
2 gene segments:
- variable
- joining
what other domain is there apart from VH and VL domains?
constant domains
what happens to make variations of the heavy chain?
- V, D and J segements
- DNA spliced out during early development of B cell to 0
- produce functional V-D-J gene
- transcription
- splicing out
- translation
what happens to make variations of the Kappa light chain?
- Vk and Jk segments
- DNA spliced out during early development of B cell
- transcription
- splicing out
- translation
what do all B cells begin by making?
IgM
Describe class switching.
memory cells produce IgG, IgA or IgE with same specificity
what do T cell independent antigens produce?
IgM antibodies in small amounts
what do the vast majority of antibody responses require?
T cells to help
what are all T cells specific for?
one antigenic determinant
Describe T cell receptors.
- Structure on T cell surface that recognises antigen
- Structurally related to immunoglobulin
- Similar complex gene structure- V,D,J,C gene segments encoding V and C regions
- Binds to antigenic peptide associated with MHC
what is TCR very similar to?
Fab fragment of an antibody
Describe the structure of TCR.
-α and β chains are linked by disulphide bond - Majority of T cells have αβ TCR -Minority of T cells have alternative, structurally similar TCR made up of different polypeptides designated γ and δ -termed γδ T cells
Why do Vα and Vβ (TCR) have hypervariable loops or CDRs?
responsible
for detecting antigenic peptide in combination with MHC
