Inhibition of human natural killer cell activity by prostaglandin D2

We have studied the effect of prostaglandin (PG) D2 on human natural killer (NK) cell activity using 51Cr-labelled K562 target cells. PGD2 caused a dose dependant inhibition of NK cell activity, producing maximal, non-toxic inhibition at a concentration of 1 X 10(-6) M. This inhibition was not due to interference with effector:target cell binding (E:TCB) and was seen using Percoll-enriched NK cells. A time dependent inhibition of NK cell activity was seen when dibutyryl cyclic AMP (DiBcAMP) and PGD2 were added in parallel to the NK cell assay suggesting that PGD2 directly inhibits NK cell activity via the adenylate cyclase system which modulates the killing process.