Relationship of phytohaemagglutinin-induced lymphocyte transformation to disease activity in systemic lupus erythematosus.

Phytohaemagglutinin-induced lymphocyte transformation was studied in 19 patients with systemic lupus erythematosus (SLE) in relation to disease activity, peripheral blood lymphocyte count, serum iron and folate levels, and corticosteroid treatment. Similar studies were performed on a group of 28 age- and sex-matched controls and on 10 patients with facial palsy who were examined before and after 7 days of high-dose corticosteroid treatment. The patients with SLE were found to have an impairment of lymphocyte transformation which was most marked in active stages of the disease and associated with a lymphopenia. This depressed transformation, which improved with the development of a remission, could not be attributed to the effects of corticosteroid treatment, inhibitory serum factors, iron deficiency, or any numerical reduction in blood lymphocytes, thus indicating along with evidence from other sources that SLE patients have a defect of cell-mediated immunity. The aetiological implications of these findings are discussed.