Influence of Amino Acid Feeding upon Antibody Production in Protein Depleted Rats. ∗

Abstract

In previous publications from this laboratory the deleterious effects of prolonged protein depletion upon antibody formation in rabbits and rats have been reported. 1 - 2 In man the association of famine and infectious disease 3 as well as the many examples of increased susceptibility to intercurrent infections evidenced by hypoproteinemic patients with chronic debilitating diseases 4 indicate a relationship between malnutrition and reduced resistance to infection. Furthermore, a correlation between a low gamma globulin level and an inability to form antibodies has been recently demonstrated. 5

We have attempted to correct the reduced capacity to produce antibodies in protein depleted rats and have found that the feeding of adequate amounts of high quality protein will quickly lead to a restoration of the antibody producing mechanism. 6 Of particular interest was the finding that a casein hydrolysate (Amigen). when fed in adequate amounts, led to a marked improvement in antibody formation relative to that of hypoproteinemic rats fed a similar and isocaloric low protein ration in equivalent amounts. It appears likeiy. therefore, that restoration of the antibody forming mechanism resulted from the utilization of amino acids in the hydrolysate. This conclusion is strengthened by the following experiment in which crystalline amino acids were fed as the source of dietary amino nitrogen.

Experimental. The methods and rations used in inducing protein depletion in the rat. as well as the techniques of bleeding, serum protein and hemoglobin determinations, and hemolysin titration have been described. 2 - 6 I n this experiment 3 comparable groups consisting each of6 young adult male rats were fed a low protein ration (diet 3E) for a depletion period of about 6 months, while an additional control group was fed a similar ration adequate in protein (diet 3C).