Flashcards in Lymphocyte Function Deck (38)
what are all lymphocytes?
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?
what synthesises and secretes immunoglobulins?
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:
what are VL domains coded by?
2 gene segments:
what other domain is there apart from VH and VL 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
what happens to make variations of the Kappa light chain?
-Vk and Jk segments
- DNA spliced out during early development of B cell
what do all B cells begin by making?
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.
1. Structure on T cell surface that recognises antigen
2. Structurally related to immunoglobulin
3. Similar complex gene structure- V,D,J,C gene segments encoding V and C regions
4. 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
-Minority of T cells have
similar TCR made up of
designated γ and δ
-termed γδ T cells
Why do Vα and Vβ (TCR) have hypervariable loops or CDRs?
for detecting antigenic peptide in combination with MHC
what are the 2 major T cell classes?
-helper T cells
-cytotoxic T cells
what is the TCR on helper T cells associated with?
CD4 and CD3
what is the TCR on cytotoxic T cells associated with?
CD8 and CD3
what are CD4 and CD8 required for?
to make an effective response to antigen
what do CD4 and CD8 mediate?
additional contacts with MHC molecules