In vitro induction of T-suppressor lymphocytes by THF, a thymic hormone, in psoriatic children.

T-lymphocyte number and function as well as the effect of a thymic hormone on the T-suppressor cell subset were studied in 22 children suffering from psoriasis vulgaris, subdivided into two groups, those with less than 20% of total skin area involved and those with more than 20% of involvement. The T-cell number was lower in the latter group than it was in the first group or in normal controls. There was no significant difference in the functional activity of T cells in the two groups of patients. The number of T-suppressor cells was significantly lower in the psoriatic children than in normal controls, being lowest in the children showing greater skin involvement. THF, a thymic hormone isolated from calves, was found in vitro to induce T-suppressor cells in the peripheral blood of the psoriatic children, suggesting that this hormone may be able to play a role in the treatment of this disease.