T-cells,+B-cells+and+Cytokines

= **__T-cells, B-cells and Cytokines__** = __**T-cells **__ A T-cell or T lymphocyte is a type of white blood cell that plays a central role in cell-mediated immunity. They contribute to immune defenses in two major ways: Some direct and regulate immune responses, whereas others directly attack infected orcancerous cells. They have many subsets including: media type="youtube" key="8buaiYBKl7U?fs=1" height="307" width="384" align="center"
 * Helper cells (Th cells): coordinate immune responses by communicating with other cells
 * Cytotoxic T-cells (TC cells, or CTLs): attack cells carrying the foreign or abnormal molecules (as alerted by DCS). they are important for viral infections because viruses often hide from the immune system while they grow inside infected cells. CTLs recognize these hidden viruses and kill the infected cell
 * Regulatory T-cells (Treg cells): shut down T-cell-mediated immunity toward the end of an immune reaction and to suppress T cells that may have confused the bodies cells with antigen
 * Memory T-cells: antigen-specific T-cells that persist long-term after an infection has been destroyed. when the same orsimilar antigen invade the body they quickly expand to large numbers of effector T-cells. this provides the immune system with "memory" against past antigen. They may be either CD4+ or CD8+ (//see clip//)

vedio: Memory cells protecting against viruses __** B-Cells **__ B-cells work chiefly by secreting antibodies into the body’s fluids. Antibodies ambush foreign antigens circulating in the bloodstream. To learn more about antibodies, visit the Factors effecting immunogenicity page. There you will find a list of antibodies produced by B-cells

__** Cytokines **__ Cytokines are chemical messengers which are released by cells in the immune system to communicate with one another and coordinate responses. Cytokines include a diverse assortment of interleukins, interferons, and growth factors. DCs secrete a diversidied panel of cytokines, many are a unique set of costimulatory molecules which allow the activation of teh naive TR cells. They secrete an important group of interleukins (IL) such as IL-1 which is involved in pathogenesis of numerous diseases with an inflammatory response. Using cytokines DCs can differentiate naive T-cells into T helper cells.

Cytokines are so important that when there is an imbalance, or cytokines are dysfunctional it can be crippling and life threatening. See autoimmune disorders.

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