Flow Cytometric Analysis of Lymphocyte Subpopulations and Th1/Th2 Balance in Patients with Polymyositis and Dermatomyositis

Abstract

Polymyositis (PM) and dermatomyositis (DM) are idiopathic inflammatory myopathies; autoimmune mechanisms are thought to play an important role in their pathogenesis. We investigated the immunocytochemical characteristics and Th1/Th2 balance of peripheral blood lymphocytes in PM and DM using flow cytometry. Eight patients with PM and 13 with DM were enrolled in this study. Of these, 8 patients with DM were examined before and after clinical remission. No patients were receiving any treatment for PM or DM at enrollment. Ten healthy subjects were used as controls. Patients with PM showed significant increases in CD3+CD4+HLA-DR+ (p<0.01) and CD19+CD23+ cells (p<0.05), and significant decreases in CD3+CD4+ (p<0.005) and CD4+CD45RO+ cells (p<0.05) compared with controls. Patients with DM showed significant increases in CD19+ (p<0.05) and CD19+CD23+ cells (p<0.05), and significant decreases in CD4+CD45RO+ cells (p<0.005) and the CD4+CD45RO+/CD4+CD45RA+ ratio (p<0.005) compared with controls. CD4+interferon (IFN)-gamma+ cells and the intracellular IFN-gamma/interleukin (IL)-4 ratio in CD4+ cells were significantly lower in patients with DM than in those with PM (p<0.05) or controls (p<0.0005 and p<0.001, respectively). The intracellular IFN-gamma/IL-4 ratio in CD4+ cells was significantly increased in DM after clinical remission compared with before (p<0.05). Both B and helper T cells are activated in peripheral blood of active PM. Th2 cells predominate in peripheral blood of active DM, and the intracellular IFN-gamma/IL-4 ratio in CD4+ cells may be useful as a clinical marker indicating disease activity.