Stress-compensation by a food supplement based on yeast plasmolysate in mitogen-activated T lymphocytes under simulated low-gravity.

T lymphocyte function is strongly depressed in vitro and in vivo under low-g conditions in space as well as simulated in clinostat. Here we describe the effect of a food supplement based on yeast plasmolysate on T cells activated in vitro with Concanavalin A and cultured in a random positioning machine. The mitotic index was measured by 3H-thymidine incorporation into DNA, the expression of activation markers CD25, CD69 and HLA-DR on the cell surface by cytofluorimetry and the secretion of the IL-2R by an enzyme immunoassay. Our data indicate that the food supplement used is capable to modulate T lymphocyte function. The addition of the food supplement increased the expression of activation markers in activated and non-activated cells. Cultivation under low-gravity conditions reduced the expression of the activation markers, but this expression was partly restored or even increased upon addition of yeast plasmolysate. On the other hand, cell proliferation and secretion of soluble IL-2 receptor was reduced after addition of the food supplement in all samples.