Natural killer cell stimulating factor
natural killer cell stimulating factor --> interleukin-12
(Science: cytokine) A 75 kD heterodimeric cytokine composed of disulfide-bonded 40 kD and 35 kD subunits that was originally identified by its ability to induce cytotoxic effector cells in synergy with less than optimal concentrations of interleukin-2.
It is released by macrophages in response to infection and promotes the activation of cell-mediated immunity. Specifically, iL-12 triggers the maturation of Thl cD4 cells, specific cytotoxic T-lymphocyte responses and an increase in the activity of nK cells and consequently, it is the initiator of cell-mediated immunity.
It enhances the lytic activity of nK cells, induces interferon production, stimulates the proliferation of activated t-cells and NK cells. Is secreted by human B lymphoblastoid cells (NC 37). May play a role in controlling immunoglobulin isotype selection as it also inhibits igE synthesis (even in the presence of anti-iFN monoclonal antibody) and as a growth factor for activated CD4_ and CD8_ t-cells independently of interleukin-2, and for CD56_ nK cells but not resting peripheral blood mononuclear cel 6d7 ls or resting or activated tonsillar b-cells.