Stimulating effects of vitamin A on PHA- and LPS-activated lymphocytes

A method of 3H-TdR incorporation in lymphocytes activated by PHA was applied. The incubation with vitamin A at a concentration of 5 μg/ml for 16 hours was followed by the incorporation, the counts per minute (cpm) of radioactivity in lymphocytes increased significantly. When the concentration was greater than 25 μg/ml or the incubation at concentration of 10 μg/ml for 72 hours, the incorporation value of 3H-TdR was remarkably decreased. The lymphocytes irradiated by 60Co gamma rays at different doses were incubated in vitro with vitamin A of 5 μg/ml concentration for 16 hours, the cpm from 3H-TdR incorporation in DNA was higher than that in control group with no vitamin A. Tests on 10 cancer patients showed that after one course of treatment with radiotherapy (75 ∼ 184 Gy), the incorporation value of 3H-TdR was decreased significantly. After adding more 5 μg/ml concentration of vitamin A, the incorporation value of 3H-TdR was remarkably greater than in the control group. These results indicated that vitamin A at adequate level is able to enhance the effect of transformation of PHA-activated lymphocytes, but the incorporation in LPS-activated B lymphocytes enhanced by vitamin A was not observed