The idiopathic inflammatory myopathies are characterized by antibody- or cell-mediated immune response against unknown muscle tissue antigens. In these diseases a cellular infiltrate, composed of T and B lymphocytes, macrophages and NK cells, may invade muscle tissue with a gradient from the perivascular space to the endomysial compartment. Muscle cells may be actively involved in the processes of mononuclear cell recruitment and activation from the blood stream to the areas of inflammation. In order to verify this hypothesis, cultured human myoblasts were tested for their capacity to express different pro-inflammatory cytokines [IL-1α, IL-1β, IL-6 and tumor necrosis factor (TNF)-α] and chemokines (IL-8, MCP-1 and RANTES) at the mRNA level and protein secretion, in the presence of the pro-inflammatory cytokines IFN-γ and TNF-α alone or in combination. We confirmed that human myoblasts expressed IL-1α and IL-6 constitutively, while IL-1β and TNF-α are detected only after treatment with pro-inflammatory cytokines; moreover, we observed that TNF-α was expressed on an autocrine fashion by myoblasts. IL-8 and RANTES were expressed constitutively while MCP-1 after proper induction. These molecular data were further confirmed by specific ELISA in the supernatant from cultured myoblasts. Our results underline the importance of human myoblasts in the recruitment of leukocytes from the blood stream and, most probably, in the cross-talk between infiltrating inflammatory cells and muscle cells, creating the conditions for a chronic inflammation. Moreover, the capacity of muscle cells to behave as cells of the immune system has to be kept in mind, also in view of i.m. vaccination and use of molecular engineered myoblasts as vehicles in gene therapy.

Eight patients with Rasmussen’s encephalitis, 40 patients with noninflammatory focal epilepsy, 104 patients with various neurologic diseases, and 16 healthy donors were tested for the prevalence of antibodies against the GluR3 receptor in serum and CSF. Reactivities against different peptides derived from various portions of this glutamate receptor subtype were detectable in a significantly higher number of patients with focal epilepsy than in those with other neurologic diseases, but they were not specific for the diagnosis of Rasmussen’s encephalitis.