Prevention of myosin-induced autoimmune myocarditis in mice by anti-L 3 T 4 monoclonal

This study was aimed at studying the effect of the induction of immune tolerance to swine cardiac myosin from anti-L3T4 monoclonal antibody injection and whether the immune tolerance could protect mice with myosin- induced myocarditis from myocardial injury. Twenty-four Balb/c mice were divided into two groups at random. All of the mice were immunized with swine cardiac myosin on the 1st day, 14th, 28th, 42nd, and 52nd day. Immune toler- ance was induced by triplicate injections of 400 µg anti-L3T4 McAb on the 0 day (intravenous), 1st day, and 2nd day (intraperitoneal) in McAb-treated group. In the saline-treated group, saline of the same volume as anti-L 3T4 monoclonal antibody was used as a control. The sera and hearts biopsies of all mice were collected on the 58th day. The anti- cardiac myosin antibody was examined with ELISA, and pathological changes of heart were observed by light micro- scope. It was shown that mice immunized with swine cardiac myosin could produce anti-myosin antibody and the anti- cardiac myosin antibody was positive in most of the saline-treated group but negative in the McAb-treated group. Morphologically, myocardial degeneration, necrosis, and infiltration of inflammatory cells were found in the saline- treated group but not in the McAb-treated group. In conclusion, this study indicated that the immune tolerance to car- diac myosin was induced by the anti-L3T4 monoclonal antibody, and accordingly myocardial injury could be prevented by induction of immune tolerance.