Etretinate therapy for psoriasis. Reduction of antibody-dependent cell-mediated cytotoxicity of polymorphonuclear leukocytes.

We monitored the antibody-dependent cell-mediated cytotoxicity of polymorphonuclear leukocytes from 14 patients with psoriasis before and during etretinate therapy. Neutrophils obtained from the patients with psoriasis at pretherapy demonstrated significantly greater cytotoxic activity than control cells. After four weeks of etretinate therapy, the cytotoxicity of neutrophils from the psoriatic patients decreased significantly and was no longer significantly different from the control value (at a 1:1 effector-to-target ratio). The decline in neutrophil cytotoxicity preceded significant clearing of our patients' psoriasis. The reduction in the antibody-dependent cell-mediated cytotoxicity of polymorphonuclear leukocytes from patients with psoriasis occurs early during therapy and may represent one of the mechanisms of action of etretinate.