Unit 12-Lesson 7: T-cell Immunity

Terms in this set (33)

T(h)-A specialized T cell that often interacts with an antigen before B cells interact with the antigen
-cooperate w/ B cells in production of antibodies (through cytokine signaling)- imp part of humoral immunity! Even more essential element of cellular immunity
-CD4+ binds to MHC II on B cells and APCs
-Helper T cells can recognize an antigen presented on the surface of a macrophage and activate the macrophage, making it more effective in both phagocytosis and in antigen presentation.\-to activate a CD4+ T helper cell, 2 signals are required, the first signal is the binding of the TCR to the processd antigen, and the second signal requires a costimulating cytokine, such as IL-2 and others. Once activated, the T(h) cell secretes cytokines that affect the effector functions of multiple cll types of the immune system

T(c) (cytotoxic T cell)-A precursor to a cytotoxic T lymphocyte (CTL)
-have the capability of attacking any target cell as they emerge from the thymus
-requires sequential and complex activation of the precursor Tc by an antigen processed by a dendritic cell and interaction with a helper T cell and costimulatory signals.
-resulting CTL is an effector cell that has the ability to recognize and kill target cells that are considered nonself
-these target cells are self-cells that have been altered by infection with a pathogen, esp viruses.
-Other important target cells: tumor cells and ransplanted foreign tissue
- Rather than reacting with antigenic fragments presented by an APC in complex with MHC class II molecules, , CD8+T cell recognizes endogenous antigens on the target cell's surface that are in combination with an MHC I molecule.
-CTL can attack almost any cell of the host that's been altered
-CD8+ binds to MHC I molecules
-A normal cell will not trigger a response by a CTL, but a virus-infected cell or a cancer cell produces abnormal endogenous antigens.
-The abnormal antigen is presented on MHC I molecules. CD8+ T cells with receptors for the antigen are transformed into CTLs
-The CTL induces destruction of virus-infected cell by apoptosis
-CTL- attaches to target cell and releases a pore-forming protein, perforin-- causes pore formation and subsequent death of the cell
-Granzymes- proteases that induce apoptosis are then able to enter through the pore