Immune-mediated conditions and antibodies associated with sporadic inclusion body myositis.

We reviewed 99 patients with sporadic inclusion body myositis (IBM), searching for a coexisting autoimmune disease, other conditions with altered immune function, or the presence of autoantibodies. Thirteen patients had one or more of 11 diseases with altered immune function. Forty-three patients had elevated titers of one or more of nine different, albeit nondisease-specific, autoantibodies. Twenty-five patients had dysproteinemia or dysproteinuria. We conclude that IBM is frequently associated with systemic immune disorders or nonspecific autoantibodies. Although aging may explain some of these phenomena, an altered immune function need to be considered in the pathogenesis of IBM.