Proliferative responses of peripheral blood mononuclear cells from psoriatic patients to T lymphocyte-stimulating cytokines (IL-2, IL-3, IL-4, and granulocyte-macrophage colony-stimulating factor) and OK-432.

We have examined the effects of four well-characterized cytokines with T lymphocyte-stimulatory activity, i.e., interleukin (IL)-2, IL-3, IL-4, and granulocyte-macrophage colony-stimulating factor (GM-CSF) on [3H]-thymidine incorporation in peripheral blood mononuclear cells (PBMs) obtained from patients with psoriasis. Under the influence of these cytokines, the incorporation of [3H]-thymidine into the PBMs was not different between psoriatic patients and healthy controls either in culture supplemented with pooled AB serum or with autologous serum. However, a potent immunopotentiator OK-432, which is a lyophilized preparation of penicillin-treated low virulence Su-strain of Streptococcus pyogenes group A3, induced significantly less incorporation of [3H]-thymidine into the PBMs from psoriatic patients than those from healthy controls [in both the culture supplemented with pooled AB serum (p less than 0.01) and that with autologous serum (p less than 0.01)]. This reduction in thymidine uptake was closely related to the disease activity as well as to the extent of skin lesions of the psoriatic patients. The defective immune response of PBMs from psoriatic patients to OK-432 probably reflects an abnormality at the level of interaction between monocytes and T cells or at the subsequent production and release of cytokines by them.