Studies of the mode of action of vitamin E in stimulating T-cell mitogenesis

Vitamin E stimulates mitogenesis produced by suboptimal concentrations of concanavalin A (Con A) and optimal concentrations of phytohaemagglutinin (PHA) but not that produced by optimal concentrations of Con A. In this report, fractionation of CBA/J murine spleen cells was performed to discover the vitamin-E-responsive spleen cell populations. It was found that removal of adherent cells on plastic and/or removal of Ia+ cells failed to decrease the effectiveness of vitamin E in enhancing mitogenesis. This indicated that vitamin E stimulates an Ia- cell population even in the absence of accessory cells. Another stimulatory effect of vitamin E was observed on whole spleen cells. When the latter were obtained from the mouse without washing, the vitamin enhanced mitogenesis as usual. Thorough washing of the spleen cells stimulated the response, and further stimulation by vitamin E was no longer seen. Readdition of the soluble splenic wash decreased the mitogenic response and restored the vitamin-E-enhancing effect. It was concluded that vitamin E stimulated mitogenesis of whole spleen cells by overcoming the effects of a soluble suppressor naturally occurring in the spleen cells by overcoming the effects of a soluble suppressor naturally occurring in the spleen. It was further demonstrated that vitamin E enhances mitogenesis long after commitment to and subsequent removal of Con A.