thymic-factor--circulating and Deficiency-Diseases

Topics: Animals; Deficiency Diseases; Humans; Immunotherapy; T-Lymphocytes; Thymic Factor, Circulating; Zinc

The thymic factor (TF) activity and lymphocyte stimulation response to phytohemagglutinin (PHA) was studied in calorie-restricted rats. Sprague-Dawley rats (28 days old) were fed a calorie-restricted diet (30% of the average food intake of control) for 4 weeks. The control group was allowed food ad libitum. After this period the body weight was 232.9 +/- 41.8 g for control rats and 66.1 +/- 4.5 g for the calorie-restricted group. The mean thymus weight was 0.699 +/- 0.153 g and 0.099 +/- 0.030 g for the control and experimental groups respectively. The TF activity was makedly reduced in the calorie-restricted group compared with the control. There was an overlap between lymphocyte stimulation responses of the two groups; however, the mean number of counts per minute (cpm) of stimulated cultures with PHA was lower and the mean cpm of unstimulated cultures without PHA was higher in the starved animals. Thus, the stimulation index was significantly lower in the deprived rats. It is suggested that deficiency of thymic inductive factors may be important in the pathogenesis of impaired cell-mediated immunity in nutritional deficiency states.

Topics: Animals; Deficiency Diseases; Energy Intake; Immunity, Cellular; Leukocyte Count; Lymphocyte Activation; Lymphocytes; Mice; Phytohemagglutinins; Rats; Spleen; Thymic Factor, Circulating; Thymus Gland; Thymus Hormones

Cell-mediated immunity is invariably impaired in protein-energy malnutrition. The effect of selected nutrient deficiencies on serum thymic factor activity was assessed in deprived rats and pair-fed controls. Deficits of calories, zinc or pyridoxine resulted in significant lowering of serum thymic factor activity whereas vitamin A deficiency did not have any effect. It is suggested that variants nutrients modulate different steps of cell-mediated immunity and that reduced thymic hormone activity may be the underlying mechanism of imparied immunity in some but not all nutritional deficiencies.

Topics: Animals; Deficiency Diseases; Energy Intake; Male; Rats; Thymic Factor, Circulating; Thymus Hormones; Vitamin A Deficiency; Vitamin B 6 Deficiency; Zinc