Decay‐accelerating factor 1 deficiency exacerbates Trypanosoma cruzi ‐induced murine chronic myositis

: Murine infection with Trypanosoma cruzi (Tc) has been used to study the role of T‐cells in the pathogenesis of human inflammatory idiopathic myositis. Absence of decay‐accelerating factor 1 (Daf1) has been shown to enhance murine T‐cell responses and autoimmunity. Methods : To determine whether Daf1 deficiency can exacerbate Tc‐induced myositis, C57BL/6 DAF +/+ and DAF −/− mice were inoculated with 5 × 10 4 trypomastigotes, and their morbidity, parasitemia, parasite burden, histopathology, and T‐cell expansion were studied in the acute and chronic stages. Results : DAF −/− mice had lower parasitemia and parasite burden but higher morbidity, muscle histopathology, and increased number of CD44 + (activated/memory phenotype) splenic CD4 + and CD8 + T‐cells. Conclusions : An enhanced CD8 + T‐cell immune‐specific response may explain the lower parasitemia and parasite burden levels and the increase in histopathological lesions. We propose that Tc‐inoculated DAF −/− mice are a useful model to study T‐cell mediated immunity in skeletal muscle tissues. Muscle Nerve 46: 582–587, 2012