Effect of dietary vitamin B6 contents on antibody production.

When mice were placed on diets extreme deficient in vitamin B6, ovalbumin-dependent antibody productions (IgE, IgG1, IgG2a) 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 (IgG1, IgE) were suppressed by pyridoxine excess diet (6 mg%), because hepatic cathepsin B activity was suppressed by the excess pyridoxine in diet.