Levamisole-induced immunostimulation in spondylarthropathies.

The term "seronegative spondylarthritis" (S.S.A.) has been assigned to rheumatic disorders with closely related clinical features, defined by seronegativity and HLA-B27 phenotype. Its pathogenesis may be linked with a genetically controlled defective immune response. Therefore, 37 men with S.S.A. were treated with levamisole (150 mg/day, 3 days/wk) to stimulate the immune reactions. In a randomised controlled crossover study these patients also received a placebo; each period ran for 12 wk. Symptomatic therapy was continued through the entire 6 mo. Serious side-effects led to withdrawal of the active drug in 9 patients. Clinical response was measured in terms of a cumulative joint index, spondylometry, morning stiffness, and a pain scale. Treatment with levamisole resulted in a significant improvement in these parameters. Radiological evidence of sacroiliitis was present in 48.6% before and after levamisole, and joint scanning with 99Tc-pyrophosphate also revealed no progress in the disease. After levamisole treatment, IgM levels fell significantly (P less than 0-014). Likewise, the previously high percentage of antibodies with weak cytotoxic activity against lymphocytes was reduced after levamisole (P less than 0-049), and an increased rate of leucocyte-migration inhibition (L.M.I) was found in the levamisole-treated group. Thus, the immunostimulating properties of levamisole may interfere with defective immunoregulation in S.S.A. and, by improving the clinical conditions, lead to a change in the course of this disease.