Cyclic AMP-dependent protein kinase as a part of the possible down-regulating pathway in the antigen receptor-regulated cytotoxic T lymphocyte conjugate formation and granule exocytosis.

Screening activities of cytotoxic T lymphocytes (CTL) are viewed as a cycle of engagements and disengagements with target cells. One of the unexplained features of CTL activation is a biochemical mechanism of an "off" signal, which would result in disengagement of CTL from the target cell and termination of exocytosis of granules. Data are presented that suggest that cAMP dependent-protein kinase (PK-A) inhibits both early and late stages of antigen receptor-regulated CTL activation and may be a part of such an off signaling pathway.