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Leukocyte activation

Leukocyte activation - to infected cells deliver toxins...

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Leukocyte activation: occurs indirectly through soluble mediators (cytokines) released from other cells or direct contact (binding) of an antigen to a cell (through antigen receptors) o Cytokines: small proteins that cause activation, proliferation, differentiation or movement of cells Lymphocyte livin’: begin as hemopoetic stem cells (can become blood cells), become lymphoid stem cells. B cells mature in the bone marrow, then move to secondary lymphoid tissues. T cells mature in the thymus, then move to secondary lymphoid tissues. Lymphocytes: large nuclei, capable of proliferation, extensive rough ER; synthesize antibodies, phagocytosis, direct killing of target cells, modulation of the immune response, include T cells and B cells; o Thymus: small organ above the heart, shrinks as you age, sorts out the T cells o Secondary lymphoid tissues: lymph nodes (neck, armpits, gut, etc) o Bone marrow: you know, you know. o T cells: modulate the immune response, cell mediated immunity, direct cell-cell contact, bind
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Unformatted text preview: to infected cells, deliver toxins, induce apoptosis; antigen receptors are distrinct from antibodies, bind antigens that are “displayed” by other self cells Positive selection: keep only those T cells with TCRs that bind adequately to MHCs in self cells, the rest undergo apoptosis Negative selection: induce apoptosis in those cells that bind too well to self cells, diversity at the expense of some self-reactivity (<5%) (B cells undergo a similar process) Cytotoxic T cells: kill self cells that are producing foreign antigens, effector cell for T cell Helper T cells: induce other cells, including cytotoxic T cells and B cells, to differentiate and proliferate, absent in AIDS patients, effector cell for T cell Surpressor T cells: can suppress the immune response to commonly encountered antigens (oral tolerance) , effector cell for T cell...
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