Immunoregulation mediated by the sympathetic nervous system.

A postulated immunoregulatory role for the autonomous nervous system was explored utilizing several in vivo and in vitro approaches. Local surgical denervation of the spleen in rats and general chemical sympathectomy by 6-hydroxydopamine combined with adrenalectomy yielded a similar removal of restraint expressed as enhancement in the number of PFC in response to immunization. Noradrenaline and the synthetic α-agonist clonidine which are, respectively, natural and artificial effector molecules of the sympathetic nervous system each strongly suppressed the in vitro induced immune response of murine spleen cells to SRBC. Further, radiometric-enzymatic assay of noradrenaline in the splenic pulp revealed a decrease in the content of this neurotransmitter just preceding the exponential phase of the immune response to SRBC (Days 3 and 4) in this site. Taken together, these findings point to a dynamic immunoregulatory relationship between the immune and sympathetic nervous system.