Role Of Osmosis In Urine Formation

Activation of CD4 T cells occurs through simultaneous engagement of T cell receptor and a costimulatory molecule on T cell by major histo-compatibility complex peptide costimulatory molecules on the APC. Both are required for production of an effective immune response in absence of co-stimulation, T cell receptor signalling alone results in energy. Signalling pathways downstream from costimulatory molecules engages PI3K pathway generating PIP3 at the plasma membrane and recruiting PH domain containing signalling molecules like PDK1 that are essential for activation of PKCtheta and IL-2 production. The first signal is provided by binding of the T cell receptor its cognate peptide presented on MHCII on an antigen presenting cell. MHCII is restricted to so called professional antigen presenting cells, like dendritic cells, B cells and macrophages to name a few. The peptides presented toHYPERLINK http//en.wikipedia.org/wiki/CD8 o CD8CD8T cells by MHC class I molecules are 89 amino acids in length the peptides presented toHYPERLINK http//en.wikipedia.org/wiki/CD4 o CD4CD4cells byHYPERLINK http//en.wikipedia.org/wiki/Major_histocompatibility_complex o Major histocompatibility complexMHCclass II molecules are longer, usually 1225 amino acids in length,as the ends of the binding cleft of the MHC class II molecule are open. The second signal comes from co-stimulation, in which surface receptors on the APC are