Elevated post-stimulatory intracellular adenosine 3,5-cyclic monophosphate (cAMP) levels are found in peripheral...

Intracellular cyclic adenosine monophosphate (cAMP) levels were measured in the peripheral mononuclear cells of 25 recipients of ABMT after stimulation with forskolin (10(-4) M), cholera toxin (1 microgram/ml) and prostaglandin E2 (PGE2, 10(-6) M). Significantly increased post-stimulatory cAMP levels were found in cells derived from patients' cells less than 30 days after ABMT (after forskolin stimulation: mean 89.7 +/- 45.4 pmol per 5 x 10(6) cells, p < 0.001; after cholera toxin stimulation: mean 78.6 +/- 37.9 pmol per 5 x 10(6) cells, p = 0.003; after PGE2 stimulation: mean 93.6 +/- 36.6 pmol per 5 x 10(6) cells, p < 0.001). However, at a later time after ABMT (7-60 months), cAMP levels had returned to normal and no significant differences in intracellular cAMP content between cells from patients and normal individuals could be detected. In addition, in six patients cAMP levels after PGE2 stimulation were measured serially pre- or peri-transplantation up to a time when haematologic recovery had occurred: the significantly elevated inducible cAMP levels found early post-ABMT returned to normal with peripheral blood reconstitution. This observation could be of interest in the post-transplantation period, because cAMP, as a 'second messenger', is a modulator of the immune system.