Proliferative response of peripheral blood mononuclear cells to autologous and allogeneic muscle in patients with polymyositis/dermatomyositis

Dermatomyositis

Dermatomyositis is a rare inflammatory myopathy with characteristic skin manifestations and muscular weakness. The disease can be categorized as adult idiopathic, juvenile, or amyopathic dermatomyositis as well as that associated with a connective tissue disease or a malignancy. Immunologic factors are most likely involved in the pathogenesis of the disease; however, genetic and environmental issues may also play important roles. Treatment with immunosuppressive agents has proved successful in the majority of patients, although significant morbidity still occurs.

Immunomodulation during treatment of polymyositis with plasmapheresis and immunosuppressive drugs

Immunologic studies were carried out in a patient with polymyositis (PM), who showed increasing muscle strength and decreasing serum creatine phosphokinase levels during 20 weeks of treatment with plasmapheresis in conjunction with prednisone and cyclophosphamide. After an initial rise, serum IgG declined with treatment. Natural killer (NK) lymphocytes were reduced by 74%, B cells by 95%, and T cells by 38%. Spontaneous proliferation of peripheral blood mononuclear cells increased dramatically. Within the CD4+ T cell subset there was increasing maturation as shown by a rise in percent mature (CD29+) cells and reciprocal decline of immature (CD45RA+) cells. At the same time CD4+ T cells became increasingly activated as shown by HLA-DR expression. The percentage of CD8+ T cells increased strongly with treatment, and they showed increased activation and expression of the cytotoxic CD29+ and CD11b- phenotypes. CD8+ T cells exhibiting CD45RA or CD11b+ suppressor phenotypes were overall unchanged; however, on follow-up a proportion of CD8+ cells expressed the activated suppressor effector (CD11b-CD28-) phenotype. In addition to control of PM by the possible deletion of activated autoreactive B and T lymphocyte clones with cyclophosphamide, the activation and maturation of CD4+ T cells during treatment may have downregulated the autoreactive disease process, either through direct antiidiotypic suppression or by induction of the observed increase in cytotoxic and suppressor CD8+ T cells.

Lymphocyte activation markers in idiopathic myositis: changes with disease activity and differences among clinical and autoantibody subgroups

We studied the immunologic correlates of disease activity and differences among subgroups of patients with idiopathic inflammatory myopathy by analysing phenotypic and activation marker expression on peripheral blood mononuclear cells (PBMC). Compared with controls, myositis patients with clinically active disease (n = 51) had significantly lower proportions of CD8+ cells and higher proportions of PBMC that expressed DR, CD3- DR, CD14- DR, interleukin-2 receptors, and the late T cell activation markers CD26 and TLiSA1. TLiSA1 expression, a marker for cytotoxic differentiation, correlated significantly with both clinical activity indices and serum levels of muscle-associated enzymes. In serial studies of seven patients, the proportion of PBMC expressing MHC class II antigen and late T cell activation markers decreased as myositis disease activity decreased, independent of type of therapy. Among the clinical subgroups, polymyositis (n = 21) and inclusion body myositis (n = 11) were virtually indistinguishable; dermatomyositis patients (n = 19) showed decreased proportions of CD3+DR+ and TLiSA1+ cells, and increased proportions of CD20+ and CD20+DR+ cells compared with the other two groups. Patients with autoantibodies to histidyl-tRNA synthetase (Jo-1 antigen, n = 11) had significantly lower proportions of CD3+ and CD4+ cells, lower CD4/CD8 ratios, and higher proportions of CD+ cells expressing CD20, compared with patients without anti-Jo-1 antibodies. These findings support the concept that activated lymphocytes, especially cells undergoing anamnestic responses and cytotoxic differentiation, are important in the pathogenesis of idiopathic myositis. Moreover, taken together with other studies, these data suggest that groups of patients segregated by clinical or autoantibody status have different mechanisms of systemic immune activation and immunopathology.