Physiologic concentrations of cortisol suppress cell-mediated immune events in the domestic pig

Mild restraint of the domestic pig (Sus scrofa) caused activation of the hypothalamic-pituitary-adrenal axis, atrophy of the thymus gland, and a significant reduction in cell-mediated, delayed-type hypersensitivity reactions. Physiologic concentrations of cortisol suppressed, in vitro, phytohemagglutinin- and concanavalin A-induced proliferation of porcine thymocytes, splenocytes, and peripheral blood mononuclear cells, even though cortisol was only mildly cytolytic. These results extend the concept of an endocrine influence on regulation of cell-mediated immune events to species other than humans and rodents.