強皮症にともなう筋障害の臨床的および病理学的研究

Abstract

In terms of the presence of clinical and pathological changes in the muscles, systemic sclerosis (SSc) is classified into two types : SSc-polymyositis overlap syndrome (SSc-PM), which is associated with lymphocyte infiltration in the muscle tissues, and simple myopathy (SSc-SM), without the infiltration. SSc-PM showed more severe muscular weakness, more myopathic electrophysiological changes, and more prominent proliferation of lymphocytes in the muscle biopsies than SSc-SM. To examine whether the muscle fibers of SSc-PM patients function as professional antigen presenting cells (APC), we investigated the expression of costimulatory molecules BB-1, B7-1 and B7-2, and their counterreceptors, CD28 and CTLA-4 (CD152), in the muscle biopsies of SSc-PM patients, polymyositis (PM) patients, and other disease controls. In SSc-PM patients, major histocompatibility complex (MHC) class Ⅱ expressing muscle fibers reacted with mono- clonal antibody against BB-1, but not against B7-1 or B7-2. CD4+ T cells constituting the majority of inflammatory cells at perivascular and endomysium expressed the counterrece- ptor CD28 and CTLA-4. In PM patients, BB-1+ muscle fibers, expressing MHC class Ⅰ, bound in cell-to-cell contact with CD8+ T cells. Our findings indicate that SSc-PM rpuscle fibers may function as professional APC in a way distinct from that in PM.