Various functions of PBMC from colon cancer patients are not decreased compared to healthy blood donors

The immune surveillance hypothesis suggests impaired immune responses to participate in development of cancer. This may partly be due to increased amounts of PGE2 and histamine, which inhibit cellular immunity. These effects are mediated by cAMP, which is increased and thereby may down-regulate IL-2 and its receptor proteins in T helper cells. The proliferative responses and IL-2 synthesis of PBMC have earlier been shown to be reduced in patients with colon cancer. Recently immune modulating agents have been demonstrated to increase the proliferative response of PBMC in vitro, probably by inhibition of adenylate cyclase activity and induction of IL-2 mRNA expression. We have therefore studied the proliferative responses of PBMC from colon cancer patients to PWM and tested the effect of immune modulating agents, such as Serotonin, Sumatriptan, and Buspirone on these PBMC. We found no difference in levels of intracellular cAMP, IL-2 mRNA expression, IL-2R mRNA expression, or proliferative responses of PBMC from colon cancer patients compared to healthy blood donors. There was no effect of the immune modulating agents on PBMC from colon cancer patients.