Immunology 4 Flashcards
T cell Receptors (TCR)
Only found on cell surfaces! Two polypeptide chains making one binding site. Are antigen specific and found on T cells. Recognize both antigen peptic and MHC molecule. These are always associated with CD3 complex… which have longer tails to signal into cell.
T cell activation by co-signaling
T cells cannot be activated by MHC and peptide alone… instead need to be co-stimulated!
They come in pairs. Examples are: B7 and CD28(or CTLA4 for inhibitory), LFA-3 and CD2, CD40L and CD40. This activation helps T cells to proliferate! Need off switch so it doesn’t proliferate forever tho!
What Happens After T cell is triggered?
Goes into activation phase where Naive T cells secrete lots of IL2, to proliferate and differentiate into diff. cells. Such as
- T-helper cells for antibody production,
- T helper cells for Delayed type Hypersensitivity (DTH, activation of macrophages into a super-killing state).
- T helper cells for anti-parasitic and allergic responses.
- T cytotoxic cells proper
Calcineurin
Responsible for activating Leukin 2 gene
Cyclosporin A (CSA) and FK504
Drugs used to stop rejection of transplant organs! They inhibit calcineurin pathways.
Best cells to activate T cells?
Although dendritic cells, B cells, and macrophages all possess the appropriate MHC and peptide combination.. dendritic cells are best APC since they always express B7 whereas B cells or macrophages only work under certain conditions.
Adjuvant
Something they put in vaccine! Doesn’t cause an immune response but jazzes up immune response! Does so by increasing B7 in B cells and dendritic cells! Thus allows for better co-stimulation to occur (more activation of T naive cells!)
After immune response
After response Antigen is removed, b cells return to resting state. Memory B cells will exist! Also have Memory T cells. Which are respond better to exposure! Diff surface antigens and stimulation requirements!
