1. Because precipitin, hemagglutination, and complement-fixation tests measure secondary manifestations of antigen-antibody interactions and are sometimes negative even after a primary antigen-antibody reaction has occurred in vitro, the incidence and amount of anti-bovine serum albumin (BSA) was evaluated in the sera from 900 children and adults by means of precipitating I131-labeled BSA-antibody complexes with 50% saturated ammonium sulfate. A similar study using I131-labeled alpha lactalbumin (ALA) was performed on 718 of this same group of sera.
2. Antibody to BSA was detected more frequently among children (75%) than among young adults 16 to 40 years of age (25%), or among older age groups (8%).
3. The incidence of detectable antibody to ALA had the same age distribution, but only half the frequency as anti-BSA.
4. In contrast to the near absence of antibody in the cord serum as measured by hemagglutination titers using red cells coated with milk proteins, most of the antibody detected in maternal sera in the present study was able to cross the placental barrier and was present in the cord sera.
5. The incidence of both anti-BSA or anti-ALA was the same in males and females.
6. If a given sera bound both IBSA and IALA, the anti-BSA activity was usually, but not always, greater than the anti-ALA activity.
7. No shared antigenicity was detected between IBSA and ovalbumin, insulin, protamine, diptheria, and tetanus toxoid, pertussis vaccine, poliomyelitis vaccine, and influenza vaccine. The apparent inhibiting effects of unlabeled bovine gamma-globulin and ALA on IBSA binding were probably due to trace amounts of BSA in these protein preparations.
8. BSA, ovalbumin, and bovine gamma-globulin had no detectable shared anti-genicity with IALA.
9. Positive skin tests to milk or BSA did not correlate with the anti-BSA levels measured in the serum.
10. The incidence of persons with anti-BSA and anti-ALA was comparable among the "patient" and "well" populations. Ten of the 31 sera with the greatest capacity to bind IBSA were from the "well" population, the remaining 21 sera were from children with a variety of disease states.
THE NATURE OF ANTIGEN-ANTIBODY COMPLEXES FORMED IN RABBITS DURING AN IMMUNE RESPONSE TO BOVINE SERUM ALBUMIN
