INTERACTIONS OF STRESS AND ENDOCRINE STATUS ON RAT PERIPHERAL LYMPHOCYTE RESPONSIVENESS TO PHYTOMITOGENS

(1) Rat peripheral blood lymphocyte responsiveness to phytohemagglutinin and to pokeweed mitogen was studied. The animals were intact or had undergone surgical removal of pituitary, thyroid, adrenals or gonads; half were subjected to non-traumatic stress for 7 consecutive days and the studies were performed with blood taken on days 1, 8 and 15. (2) In intact rats there was a significantly increased responsiveness to pokeweed mitogen 1 week after cessation of the stress. (3) In non-stressed animals, adrenalectomy was associated with lower responses to pokeweed mitogen. (4) There was no influence of stress on responsiveness to pokeweed mitogen in any of the surgically-treated rats; however, in these rats, hypophysectomy and thyroidectomy were associated respectively with reduced and increased responsiveness to phytohemagglutinin. (5) Considering all stressed animals, i.e. intact and surgically treated, thyroidectomy, adrenalectomy and castration led to a greater responsiveness to phytohemagglutinin and hypophysectomy had the reverse effect. (6) The data support the concept that both stress and hormonal status may influence immune responses and may do so in an interrelated manner. © 1979.