Studies on thymic humoral factor prepared from guinea pigs: the influence of dietary vitamin C.

Abstract

The present study describes a bioassay system for evalulating the activity of thymic humoral factor. The X-irradiation depressed weight and hexose monophosphate shunt enzyme activity of rat thymus, spleen, and lymph nodes were partially restored by thymus extract, but not by spleen extract injections. The influence of dietary vitamin C on the maintenance or production of thymic humoral factor was also investigated. Thymus extracts prepared from guinea pigs maintained on high levels of vitamin C accelerated the regeneration of lymphatic tissue weight and restored hexose monophosphate shunt enzyme activity, whereas further loss of tissue weight and depressed enzyme activity occurred in the irradiated rats treated with thymus extract prepared from guinea pigs maintained on low levels of vitamin C. The evidence thus suggests that thymic humoral factor production or activity is dependent in part on vitamin C. The concentration of total ascorbic acid in the thymus of hypovitaminotic guinea pigs had decreased 40% below normal and the ratio of oxidized to reduced ascorbic acid had increased 5-fold, indicating the oxidation state of ascorbic acid is particularly important for the maintenance of thymic humoral factor activity.