Experimental allergic myositis: strain 13 guinea pig immunised with rabbit myosin B fraction.

Of 32 guinea pigs (Hartley and strain 13), 20 were immunised with whole muscle homogenate, microsome or myosin B fraction of rabbit skeletal muscle with Freund's complete adjuvant (FCA); the purified myosin fraction was also used as an antigen in four animals at a concentration lower than other antigens; four were injected with normal saline and FCA; other four had no injection. Five histological changes, namely necrosis, phagocytosis, central nuclei, inflammation and vacuoles, in the quadriceps femoris muscle were compared by quantitative analysis. The group immunised with myosin B fraction showed necrosis, phagocytosis and inflammation more frequently than those immunised with other preparations (p less than 0.05). The changes were more frequent in the strain 13 than in Hartley (p less than 0.05).