Specific Acquired Immunity Flashcards
What pathway is taken to display antigens on MHC Class I?
- Antigens are synthesized with in the cell
- Cell antigens of antigens from cell infections
What cell types express MHC Class I?
Expressed on all cells except RBCs. Lack of expression on RBCs may play a role in persistence of the malaria parasite, plasmodium
What T cell types interact with MHC Class I?
Recognized by CD8+ killer T cells
What is the result of T cell interaction with MHC Class I?
It surveys every cell in the body and makes sure it’s doing what it should be doing,
If CD8+ cell is activated:
-CD8+ cells expand/clone
-Daughter cell binds cell showing activation peptide
-T cell delivers lethal hit to that cell by signaling the target cell to commit suicide through apoptosis
-Target cell’s nucleus disintegrates and the cell dies
What pathway is taken to display antigens on MHC Class II?
Antigens are products of uptake from the environment and phagocytosis.
What cell types express MHC Class II?
Expressed on monocytes/macrophages, dendritic cells, B cells and epithelial cells of the thymus.
What T cell types interact with MHC Class II?
Recognized by CD4+ helper T cells.
What is the result of T cell interaction with MHC Class II?
Antibodies will be produced? B cell response?
What is is MHC known as?
HLA (human leukocyte antigens) - inherited in mendelian fashion - some from each parent
What are the common lymphocyte markers?
Antigen receptors & CDs
Which lymphocytes markers are expressed on T cells?
- TCR (alpha-beta or gamma-delta) - antigen receptor
- CD3 (part of TCR complex)
- Some have CD4, some have CD8, some have CD23
Which lymphocyte markers are expressed on B cells?
Immunoglobulin (Ig) - antigen receptor
- CD1
- CD19
- CD20
- CD23
- CD40
- CD79a (part of BCR complex)
- CD79b (part of BCR complex)
What are the five specialized subtypes of T helper cells?
Th1, Th2, Th17, Tfh, Treg (not helper: CTL)
What main cytokines drive a HSC to a lymphoid progenitor cell?
IL-7 and IL-3
What cytokines are general activators of T cells?
IL-2 and IL-15
What cytokines drive T helper cells to Th1 helper cells?
IL-12 and IFN-gamma
What cytokines drive T helper cells to Th2 helper cells?
IL-4
What cytokine down regulates Th1?
IL-10
What cytokines down-regulates both Th1 and Th2?
TGF-beta
Are T helper cells considered CD4+ or CD8+ T cells?
CD4+ T cells
-CD4+ increases their affinity for antigen and helps them get activated.
What do Th1 (helper) cells do?
- Recognize antigen and make a lymphokine that attracts thousands of macrophages (heavy duty phagocytes) to area where antigen has been recognized.
- This intense inflammation can wipe out a serious infection (or a transplanted kidney)
What do Th2 (helper) cells do?
- Stimulated macrophages to become ‘alternatively activated’, able to function in walling-off pathogens and promoting healing, a process that usually takes place after the pathogen-killing Th1 response.
- They are very important in parasite immunity
What do Th17 cells do?
- Similar to Th1 in that their main role is to cause focused inflammation
- More powerful than Th1
- Have been implicated in many serious forms of autoimmunity
What do Tfh (follicular helper) cells do?
- Stimulated by antigen and migrate from T cell areas of lymph nodes into the B cell follicles
- In B cell follicles, they help B cells get activated and make IgM, IgG, IgE and IgA antibody subclasses.