Suppression of myosin-induced and adoptively transferred myocarditis by prior treatment with complete Freund's adjuvant.

BACKGROUND: We evaluated the effect of pretreatment with complete Freund's adjuvant (CFA) on experimentally induced myocarditis concomitant with the assessment of antigen-specific properties of disease-triggering lymphocytes. METHODS AND RESULTS: Rats pretreated with CFA a week prior to myosin immunization developed a significantly attenuated myocardial inflammation as compared to control-treated animals. Furthermore, prior administration of CFA virtually abolished histological evidence of myocarditis induced by transfer of antimyosin lymphocytes. CFA administered subcutaneously prior to myosin immunization resulted in a significant reduction in lymph node cell reactivity to myosin. Assessment of cultured medium from lymphocytes obtained from CFA-pretreated myosin-immunized rats revealed reduced levels of interferon gamma but an increased production of IL-10, suggesting an induction of a Thl to Th2 switch. CONCLUSIONS: Thus, CFA treatment suppressed both myosin-induced as well as adoptively transferred myocarditis concomitant with induction of antigen-specific unresponsiveness to myosin and skewing of the immune response in favor of a Th2-dominated profile.