Evaluation of lymphocyte subpopulations and T-cell functions in psoriasis

Peripheral blood lymphocytes from patients with cutaneous psoriasis and from normal subjects were analyzed for their cell surface markers and their responsiveness to mitogens. In addition, thymic hormone levels were evaluated in psoriatic and control sera by a rosette assay. Compared to the control group, normal results were found for B cells (surface immunoglobulins and EAC rosettes) and for Fc-receptor-bearing cells (EA Rosettes). Conversely, lower than normal results were noted in psoriatic patients for T cells (E rosettes, active E rosettes, and anti-human T-lymphocyte antigen serum). The proliferative response to concanavalin A was significantly depressed in the psoriatic group, whereas phytohemagglutinin and pokeweed mitogen induced normal [ 3H]thymidine incorporation rates. Lastly, thymic factor levels were significantly higher in psoriatic than in normal subjects of the same age. The dissociation of low T-cell numbers and decreased concanavalin A responses with normal or high thymic factor levels and normal phytohemaglutinin stimulation may be explained in several ways. It could be hypothesized that these tests explore different T-cells subpopulations and functions not identically altered in psoriasis.