All tags Immunology T cell activation interactive pathway

T cell activation interactive pathway

T cell activation refers to the elicitation of an immune response by a T cell, upon stimulation of the latter by an antigen presenting cell (APC). This interactive pathway explains the main stimulatory signals that trigger T cell activation as well as their downstream pathways.

​​​​​​T cell activation requires two simultaneous signal. The first is binding of the T cell receptor complex (TCR) to a major histocompatibility complex (MHC) molecule carrying a peptide antigen. The second is provided by the binding of the co-stimulatory receptor CD28 to proteins in the surface of the APC, such as B7-2 or B7-1.

Activation of a TCR leads to dephosphorylation of the kinases FYN and LCK by CD45, previously recruited and activated by CD4 and CD8 co-receptors. FYN and LCK phosphorylate immunoreceptor tyrosine-based activation motifs (ITAMs) on the TCR which then bind the ZAP-70 kinase. Activated ZAP-70 eventually triggers a number of immune responses such as antibody production, activation of phagocytic cells and direct cell killing.