Effect of dietary vitamin B 6 contents on antibody production

When mice were placed on diets extreme deficient in vitamin B 6 , ovalbumin‐dependent antibody productions (IgE, IgG 1 , IgG 2a ) were significantly suppressed, and alanine aminotransferase activity in the liver was also significantly decreased. In the case of pyridoxine excess (6 mg% = about ten times standard amount) in a 70% casein diet, ovalbumin‐dependent antibody productions were also considerably suppressed. These responses were weaker in a low casein (5%) or normal casein (20%) diet than in a 70% casein diet. The administration of high doses of pyridoxine (6 mg%) resulted in the suppression of hepatic cathepsin B activity. Therefore, we conclude that ovalbumin‐dependent antibody productions (IgG 1 , IgE) were suppressed by pyridoxine excess diet (6 mg%), because hepatic cathepsin B activity was suppressed by the excess pyridoxine in diet.