SERUM C3 CONTENT IN VITAMIN B-12-DEFICIENT RATS

As a clue to clarifying the role of vitamin B-12 (B-12) in the functio n of the complement system, serum C3 content was determined in B-12-de ficient rats, and the effect of the administration of methylcobalamin (CH3-B-12) on the serum C3 content was also studied. It was found that the serum C3 content in rats fed on a vitamin B-12-deficient diet for 90 and 120 days significantly decreased compared with that in control rats. The administration of CH3-B-12 restored the serum C3 content to control levels. The above results indicate that B-12-deficiency depre ssed the serum C3 content and lowered humoral immunocompetance and tha t these changes were ascribable to B-12-deficiency.