Suppressive Effect of Ferritin on in Vitro Lymphocyte Function

Summary. This study describes the effect of ferritin on lymphocyte function in vitro. Peripheral blood lymphocytes isolated from normal donors were incubated with purified human splenic ferritin, and the mitogenic effect of phytohaemagglutinin (PHA), concanavalin A (Con A), pokeweed mitogen (PWM) and mixed lymphocyte reaction (MLR) were assessed by the uptake of 3H-thymidine (3H-TdR). Ferritin (0·25–5·0 μg/ml culture) caused a marked suppression of PHA and Con A blastogenesis but had no suppressive effect on PWM-induced transformation. Maximal suppression was obtained at a ferritin concentration of 1 μg/ml and this was not enhanced by increasing ferritin concentrations. Ferritin also reduced the Con A capping phenomenon in normal lymphocytes from 22% to 6%, suppressed the MLR reaction but had no effect on the ability of normal lymphocytes to form E, EA and EAC rosettes or on in vitro lymphocyte cytoxicity against the K-562 cell line. Visual proof of the suppressive effect of ferritin on mitogen induced blastogenesis was provided by scanning electron microscopy, and direct evidence for the ability of lymphocytes to bind ferritin was obtained from studies with radioiodine labelled ferritin. The above findings indicate that ferritin suppresses certain parameters of T-lymphocyte function in vitro. The relation of the present findings to recognized abnormalities of T-cell function encountered in certain neoplastic disorders associated with high serum ferritin levels is at present unknown.