Effects of Nicotinic Acid on Specific Antibody Production

In a previous paper 1 it was shown that ascorbic acid mixed with or injected simultaneously with horse serum hastens and augments specific-precipitin production in rabbits. We have extended this work to include other “activators” of tissue-enzymes, the present paper summarizing the “co-antigenic” effects of sodium salts of nicotinic acid.

In our initial tests with this activator six 2000 g rabbits were injected intravenously with 0.5 cc horse serum. Three of these animals were then given intravenously a fresh mixture of 50 mg nicotinic acid plus 22 mg Na₂CO₃ in 1 cc NaCl solution. The rabbits were bled at frequent intervals, and the average precipitin-titer (ring test) was determined for each group. Data thus obtained are recorded in Table I.

The results in this preliminary series are similar to those previously obtained with Vitamin C, except that the percentile increase in antibody-production is less than with ascorbic acid.

In order to determine the optimal antibody-stimulating dose of nicotinic acid, 21 rabbits were divided into 7 groups of 3 each. Each animal was given a single intravenous injection of 0.5 cc horse serum, mixed with varying amounts of freshly neutralized nicotinic acid. The average titers for 4 of the 7 groups are recorded in Fig. 1.

Fig. 1 shows that under the conditions of the test, relatively small doses of sodium nicotinate inhibit specific-precipitin production. Medium doses may be without demonstrable effect, while massive doses augment antibody-production. Even with massive doses, however, antibody stimulation is less pronounced than that previously reported with ascorbic acid.

No theory is suggested to account for this dual effect. The phenomenon, however, is reminiscent of dual effects reported by Walbum, et al., in their studies of the antibody-stimulating or inhibiting effects of metallic salts.