Analysis of macrophages, activated cells and T cell subsets in inflammatory myopathies using monoclonal antibodies.

The availability of monoclonal antibodies which react with lymphocytes and cells of the MPS permits the construction of panels of reagents for immunophenotypic analysis of infiltrating cells in IM. We used immunohistochemical methods to immunophenotype inflammatory cells in muscle biopsies of patients with PM, DM and IBM. The cases of PM and IBM contained an intense MPS cell infiltrate in perivascular and endomysial areas, closely surrounding muscle fibers and occasionally included within the muscle fiber itself; an infiltrate of Leu-6+ cells with a morphology consistent with MPS cells in perivascular and endomysial distribution and occasionally closely apposed to muscle fiber membranes; lymphocytes and MPS cells expressing the IL2-R, and approximately equal numbers of T cells of helper-inducer and suppressor-cytotoxic phenotypes. DM cases had fewer MPS cells and relatively more B cells than T cells.