Striking impairment of the antibody response to sheep erythrocytes was found in pyridoxine-deficient rats. Deficiencies in the three other B factors required by the rat, and low protein feeding, having effects on body weight comparable to pyridoxine deficiency, failed to influence the antibody response studied.
Confirming previous observations, a striking loss of thymic and lymphoid tissue occurred in the pyridoxine-deficient animals. A marked deficit in thymus weight also resulted from the feeding of a diet low in thiamin. Histologically, however, lymphoid atrophy was less pronounced in thiamin-deficient rats than in those deprived of pyridoxine.