Immune responses in muscle

Intramuscular immune responses occur in muscle infections, intramuscular vaccination, graft-versus-host disease, myoblast transfer therapy and autoimmune muscle diseases. Immunocytochemical studies have defined characteristic inflammatory lesions that help to distinguish between different forms of inflammatory myopathy. In some cases of inflammatory myopathy, CD8⁺ T cell lines derived from muscle show a low but significant cytotoxic effect against autologous myotubes, indicating that T cells can react to muscular autoantigen(s). Further, human myotubes can be killed by allospecific cytotoxic T cells and by natural killer cells. This is relevant to myoblast transfer therapy. Cytokines can induce a variety of immunologically relevant surface molecules on human myoblasts and myotubes in culture. After treatment with γ-interferon, myoblasts can function as antigen-presenting cells and stimulate antigen-specific CD4⁺ autologous T cells.