CD8+ cell changes in psoriasis associated with roxithromycin-induced clinical improvement.

We have shown that T cell receptor BV2- and BV8-bearing CD8+ cells are decreased in the peripheral blood of psoriatic patients, while T cells possessing these BVs accumulate in psoriatic lesions. T cells homing to skin express cutaneous lymphocyte-associated antigen (CLA), and bacterial superantigens that trigger psoriasis promote this expression. Roxithromycin has immunomodulatory potency and its effectiveness for psoriasis has been proposed. Therefore, we monitored BV usage and alteration of superantigen-promoted CLA expression in circulating CD8+ cells of psoriatics before and after roxithromycin therapy. After roxithromycin treatment, circulating BV2- and BV8-bearing CD8+ cells were increased and CD8+ cells exhibited reduced expression of CLA when stimulated in vitro with bacterial superantigens. It is suggested that roxithromycin downregulates augmented expression of CLA by CD8+ cells, thereby suppressing their skin-homing and elevating the numbers of circulating BV2- and BV8-positive CD8+ cells. Such events may be included in part in the improvement of psoriasis with roxithromycin.