Immunoglobulins & Cytokines Flashcards
Immunoglobulin isotypes
Mature B cells express IgM & IgD. Switching (mediated by cytokines & CD40 ligand on Th cells) to plasma cells that secrete IgA, E, G.
IgG
Main Ab in 2nd (delayed) response to Ag. Abundant. Fixes complement. Crosses placenta (passive immunity in infants). Opsonizes bacteria. Neutralizes bacterial toxins & viruses.
IgA
Prevents attachment of bacteria/virus to mucous membranes. Does NOT fix complement. Monomer in circulation. Dimer when secreted. Crosses epithelial cells by transcytosis. In secretions (tears, saliva, etc). In early breast milk -> colostrum. (J-chain holds the dimer together + secretory piece)
IgM
Produced in 1st (immediate) response to Ag. Fixes complement. Does NOT cross placenta. Ag receptor on surface of B cells. Monomer on B cell or pentamer (shape allows to trap free Ag out of tissue while humoral response evolves)
IgD
Unclear fx. On surface of B cells in serum.
IgE
Binds mast cells & basophils. Cross links when exposed to allergen, mediating type I hypersens (ie- via histamine). Mediates immunity to worms by activating eosinophils. Lowest [ ] in serum.
IL-1
An endogenous pyrogen. Causes fever, acute inflammation. Activates endothelium to express adhesion molecules; induces hcemoine secretion to recruit leukocytes.
IL-6
Endogenous pyrogen. Causes fever & production of acute-phase proteins.
IL-8
Major chemotactic factor for neutrophils
IL-12
Induces differentiation of T cells to Th1 cells. Activates NK cells.
TNF-alpha
Mediates septic shock. Activates endothelium. Causes leukocyte recruitment & vascular leak.
IL-2
Stimulates growth of helper, cytotoxic, & regulatory T cells.
IL-3
Supports the growth & differentiation of bone marrow stem cells. Fxs like GM-CSF
IFN-gamma
Activates mac.phages & Th1 cells. Suppresses Th2 cells. Antiviral & antitumor properties.
IL-4
Induces differentiation into Th2 cells. Promotes B cell growth. Class switching to IgE & IgG
