A patient with inclusion body myositis was treated with a course of 22 leukocytaphereses combined with prednisone and azathioprine therapy. He improved clinically during an induction phase of frequent cytapheresis, which reduced the circulating levels of T lymphocytes and monocytes and decreased the ratio of the T4+ to T8+ lymphocyte subsets. During subsequent maintenance cytapheresis there was partial recovery of the T4+ population without recovery of T8+ lymphocytes, and the patient lost most of his clinical improvement. In contrast to T lymphocytes and monocytes, there was no persistent reduction in circulating Blymphocyte levels during the course of therapy. T8+ lymphocyte populations may regenerate more slowly than T4+ lymphocytes following depletion with leukocyatpheresis combined with prednisone and azathioprine therapy. A loss of of T8+ suppressor relative to T4+ helper-cell function could lead to an intensification of autoimmune conditions.