Inhibitory effect of deoxypyridoxine on the action of certain mitogenic factors.

We studied the effect of pyridoxine deficiency state on the responses of human lymphocytes to certain mitogenic factors. Deoxypyridoxine (DB6), a potent pyridoxine antagonist, considerably inhibited Bromodeoxyuridine (BrdU) incorporation into the newly synthesized DNA of lymphocytes cultured with Phytohemagglutinin (PHA) and Concanavalin A (Con A) in separate sets of experiments. The addition of deoxypyridoxine simultaneously with or few hours prior to initiation of cell cultures did not significantly alter the inhibitory action of deoxypyridoxine. Titration studies of deoxypyridoxine showed the direct relation between the concentration of deoxypyridoxine and the degree of DNA synthesis' inhibition with subsequent lymphocyte proliferation. The results obtained with monoclonal antibody (anti-BrdU) studies were further confirmed with tritiated thymidine incorporation (3H Thymidine) studies. Addition of pyridoxine concurrently with the addition of DB- or 8 hours later than initiation of lymphocyte incubation period was capable of effectively reversing the inhibition caused by its antagonist, the level of DNA synthesis reaching that of the control cultures where only PHA or Con A were present. Our results confirm part of previously reported findings concerning the involvement of vitamin B- in immune processes.