Flashcards in The Immune Response I Deck (21)
Describe the Th1 cell response.
After being transported to the APC cell membrane, the antigenic peptide MHC class II complex is presented to CD4+ T (helper) cells. CD4+-Th1 cells are activated and the cell clone divides logarithmically and secretes IL-2, IFN-y, and TNFa.
What is secreted in the Th1 cell response?
IL-2, IFN-y, TNFa.
What is the function of IL-2?
IL-2 is necessary for T and B cell transformation.
What is the function of IFN-y?
IFN-y is a potent macrophage and natural killer (NK cell) activator. It enhances cell mediated immunity and triggers HLA antigen presentation by endothelial cells.
What is downregulated by IFN-y?
IL-4 synthesis by Th2 cells; In this way, it suppresses antibody formation.
What is the function of TNF-a?
Activation of macrophages, stimulation of the acute-phase response, and collaborating with IL-1 in the acute phase response.
Describe the Th2 cell response.
Following antigen activation AND stimulation by IL-2, the CD4+-Th2 cell responds by transforming, differentiating, and dividing logarithmically while secreting IL-4, IL-5, IL-10, IL-13.
What is secreted in the Th2 cell response?
IL-4, IL-5, IL-10, IL-13.
Which CD4 pathway activates B cells?
What cell types are activated by the Th1 CD4+ pathway?
Macrophages, NK cells, T cells. (Cell mediated Immunity)
What is the function of IL-4?
Favours development of antibody synthesis by stimulating B-cell differentiation; downregulates IFN-y by TH-1 cells and can thus suppress CMI. IL-4 is necessary for IgE production.
What is downregulated by IL-4?
IFN-y by Th1 cells- this suppresses CMI.
What is the function of IL-5?
To function synergistically with IL-4 and IL-2 to help in B cell differentiation; facilitation of IgA synthesis; stimulation of growth and differentiation of eosinophils.
What is the function of IL-10?
Functions like IL-4 by inhibiting Th1 cell release of IFN-y and IL-2, thereby negating macrophage activation by IFN-y.
What is the function of IL-13?
Mimics IL-4 actions, inhibiting Th1 cytokine release.
Describe the initial B cell response.
Antigen selects the clone of B cells with the membrane bound IgM antigen receptor that is specific for the antigen epitope. Binding of antigen along with stimuli from T cell cytokines IL-2 and IL-4 triggers differentiation of the B cell clone into a large blast cell and logarithmic division occurs.
What is the function of IL-5 in B cell maturation?
Allows the B cell to acquire the cytoplasmic machinery necessary for antibody synthesis; H and L chains are synthesized and assembled.
What is the function of IL-6 in B cell maturation?
Contributes to terminal differentiation of B cells into a plasma cell; secretion of IgM then occurs.
Which MHC pathway involves presentation of intracellular organisms (viruses, parasites, etc)?
Which MHC pathway involves endocytosis/ phagocytosis of antigen?