Human myoblasts modulate the function of antigen-presenting cells

Muscle biopsy specimens of myositis patients were analyzed for the presence of dendritic cells (DC) and macrophages (MPh) by immunohistochemistry. The interaction of DC and myoblasts (MB) was studied by coculture and effects on DC phenotype and function were assessed by flow cytometry and T-cell proliferation assays. Effects of MB-lysates on the phagocytic capacity of MPh were analyzed in bead-incorporation assays. Myositis specimens revealed a tendency towards more immature DC. MB modulated the maturation state of DC and DC recovered from MB-coculture had an inhibitory effect on T-cell proliferation. MB-lysates strongly stimulated MPh phagocytosis. Hypothetically, MB might modulate APC, counterbalancing immune-mediated damage.