Lecture 17 - T cells and cytokines Flashcards
during activation of a naiive CD4+ helper cell, what contributes to the specificity of the interaction between the T cell and an APC?
specificity between:
TCR and HLA class II molecule
TCR and antigen being presented
HLA II and antigen
CD4 and the HLA II
how many lymph nodes does the average person have?
around 500
how do helper T cells know to go to the T cell zone of the lymph nodes to be activated?
cytokines
how does an APC get to the lymph nodes to help helper T cells become activated?
antigen presenting cells follows cytokines/chemokines towards the lymph nodes and enters via the afferent vessel
the cytokine interleukin-2 is a?
potent proliferation factor
how does an activated but not mature helper T cell mature?
with the help of the antigen presenting cell and other helper t cells secreting IL-2, they proliferate and differentiate to form mature effector cells
what happens to helper effector cells after becoming mature?
they leave the lymph nodes and go into the periphery:
- produce cytokines to recruit other immune cells
- activate other T and B cells
true or false, both types of T cells, B cells and plasma cells all form memory cells
false, plasma cells do not form memory cells, but B and T cells do
true or false, memory T cells are more abundant for a specific antigen after initial exposure than naiive T cells and therefore can initiate a faster immune response next exposure
true
what do adhesion molecules do during T cell activation?
hold the plasma membrane in close enough proximity so other molecular interactions can occur
what are some examples of adhesion molecules used in T cells and APCs in T cell activation?
selectins and integrins
what is ‘signal 1’?
the binding of an antigen-specific T cell receptor with an HLA molecule containing a specific antigen.
also the CD4 or CD8 protein binding to the HLA is a part of signal one
what is ‘signal 2’
co-stimulation - ligand on APC binds to receptor on T cell
- added layer of security to ensure the T cell being activated fully receives further verification
should you study the pictures in the slides because he likes to ask what shape represents what protein?
yes
describe co-stimulatory molecule structure
- pairs of surface molecules expressed in cell-cell interactions
- B7 family (CD80 and CD86) ligands on APC/dendritic cells
- CD28 activation receptor on T cells
Co stimulatory molecules can be expressed ___________, and modulate ?
transiently, immune activation processes
what would happen if an APC presents a non-pathogenic protein?
the B7/CD80/CD86 ligand won’t be expressed, so we end up with only a partially activated T cell, which leads to ANERGY, which switched off the T cell from further activation
what would happen if an APC presents a pathogenic molecule e.g bacteria?
the B7/CD80/CD86 ligand will be expressed, so we end up with a fully activated T cell.
after signals 1 and 2, what happens?
Signal 3:
cytokines (IL-2 proliferation factor) are released by the APC and bind to the cytokine receptor of the maturing T cell causing proliferation
what recruits B and T cells into the lymph nodes from the blood?
chemokines
(cytokines)
what are support cytokines?
keep B and T cells in the lymph nodes alive (many different mechanisms)
would B and T cells survive without cytokines?
no, cytokines are essential for survival of B and T cells
true or false, cytokines are involved in everything biology, not just immunology
true
what produces cytokines?
CD4+ and most other cells of the body
