Studies on Serum Fractions

Summary

1. 1. By immunizing rabbits with injections of washed flocculi of diphtheria-toxoid-antitoxin or specific precipitates of pneumococcic S.S.S. an antiserum reacting with horse-serum can be obtained. For lack of a better name the antiserum prepared with the former flocculi has been termed “precipitin-versus-antitoxin (P.V.At.)” and that with the latter precipitate “precipitin-versus-antibacterial antibody (P.V.Ab.).”

2. 2. By the optimal-proportions-method of Dean and Webb it was found that P.V.At. shows only one zone with all the sera tested, antitoxic, antibacterial and normal horse-sera. The fraction reacting with P.V.At. was found mainly in the water-soluble fraction of the serum tested.

3. 3. P.V.Ab. showed two zones when tested against antitoxic sera, one or two against antibacterial and normal horse-sera. In cases of only one zone the presence of two antigen-antibody systems was shown by using serum-fractions and also by absorption of P.V.Ab. by diluted antidiphtheric serum. The zone that appears in the water-insoluble fraction was named “primary zone” and that in the water soluble fraction “secondary zone.” Taylor and Adair (13) concluded from their experiments that while (a) a single zone does not necessarily indicate a single antigen-antibody system, (b) multiple zones suggest the presence of more than one antigen-antibody system.

4. 4. The fraction giving rise to the primary zone against P.V.Ab. was designated as “B-fraction or Felton-fraction” and that causing the zone against P.V.At. as “A-fraction.” Relation of the secondary zone to A-fraction was suggested.

5. 5. The supernatent of the mixture of P.V.Ab. with an antitoxic serum in their optimal proportion of the secondary zone showed only one zone with all the antitoxic and most of the antibacterial sera tested, while it did not show any zone at all when tested against some normal horse sera. These sera were taken from ponies and horses of a horse breeding station.

6. 6. If the ratio of different sera to P.V.At. or P.V.Ab. may be taken as an indication of the relative amount of respective fraction, it may be concluded from table 7 that the A-fraction-content is larger in antitoxic sera than in antibacterial ones while the B-fraction-content of the former is much smaller than that of the latter and also that the B-fraction-content of some normal horse sera was hardly detectable.