STRESSOR-INDUCED ALTERATIONS OF THE SPLENIC PLAQUE-FORMING CELL RESPONSE - STRAIN DIFFERENCES AND MODIFICATION BY PROPRANOLOL

The effects of stressor application on the splenic plaque-forming cell (PFC) response was assessed in two strains of mice: the BALB/cByJ str ain, which is highly responsive to stressors; and the more hardy DBA/2 J strain. Both strains exhibited a peak PFC response 120 h following a dministration of sheep red blood cells (SRBC; 5 x 106 cells). Stressor exposure reduced the immune response; however, the appearance of such an outcome was dependent upon the time at which the stressor was appl ied relative to SRBC inoculation. In DBA/2J mice, foot-shock applied e ither immediately after SRBC inoculation or at the time of the peak im mune response (120 h) resulted in suppression of the PFC response. In BALB/cByJ mice, both stressor severities provoked an immunosuppression when applied 120 h after inoculation, but when applied 96 h after imm unization only foot-shock reduced the PFC response. At other intervals , the stressors were without effect. Pretreatment with the beta-norepi nephrine antagonist propranolol precluded the immunosuppression elicit ed by a stressor applied 96 h after inoculation, but did not affect th e reduction of the PFC response elicited by a stressor applied 120 h a fter inoculation. It is suggested that several factors may contribute to stressor-provoked alterations of the immune response, and that the contribution of these factors vary over the course of an immune respon se being mounted.