Description: The 6B11 monoclonal antibody reacts with an epitope of the CDR3 formed by the germ-line configuration of the V alpha 24 and J alpha 18 of the TCR alpha locus, which results in the expression of an invariant T-cell receptor (TCR) expressed by invariant NK T cells (iNKT). This TCR is homologous to the murine V alpha 14 J alpha 18. This TCR alpha chain pairs with a restricted set of rearranged TCR beta chains, with V beta 11 being the most prominent in humans. NK T cells are restricted by the CD1d molecule and are activated by a CD1d-presented glycolipid ligand, which results in the rapid production of IL-4, IL-13 and IFN gamma. Although iNKT cells have NK-like cytolytic activity, they are considered regulators of immune responses because they rapidly produce large amounts of both Th1 and Th2 cytokines in autoimmune disease, infectious disease, and cancer. The number of iNKT cells present in peripheral blood of normal humans shows considerable variability ranging from 0.01-1% of total peripheral T cells.