Effects of Retinoids on Human Lymphocyte Functions in vitro

1 E-Rosette formation in vitro, lymphocyte mitogenesis and natural killer (NK) activity of human blood lymphocytes were strongly inhibited by high concentration (10-4 M) of retinol or retinal. Other retinoids at 10-4 M (retinoic acid and 13-cis-retinoic acid) and lower concentrations (10-7 or 10-9 M) of retinol, retinal and carotenes also inhibited E-rosette formation. 2 Lymphocyte transformation responses induced by concanavalin A (Con A) or pokeweed mitogen (PWM) were also inhibited while NK activity was not affected. 3 There was a remarkable depression of the total number of viable lymphocytes after incubation with retinol or retinal 10-4 M. However, other retinoids, 10-7 and 10-9 M of retinol and retinal and carotenes did not show marked decrease of lymphocyte number or viability even after prolonged incubation (48 h). 4 The mechanism of inhibition by retinol or retinal (10-4 M) is due in part to the decrease of viable lymphocytes. It is unclear how other retinoids, carotenes and lower concentrations (10-7 or 10-9 M) of retinol or retinal inhibit E-rosette formation or lymphocyte transformation.