The subclasses of human IgG antibodies against tetanus toxoid.

The subclass of IgG antibodies against tetanus present in the serum of thirty-five human individuals, who received an injection with tetanus toxoid, was determined. Six successive serum samples were obtained from twenty-five normal individuals (laboratory personnel) 0, 3, 7, 14, 28 days and 2-3 months after the injection with tetanus toxoid had been given. Another ten serum samples were obtained from ten persons with a positive IgE-RAST, taken 2 weeks after the injection. Antibodies were determined with a quantitative immunofluorescence method known as the defined antigen substrate spheres (DASS) system. The normal individuals in whose serum a clearly positive IgG binding was found (nineteen) showed activity in all four subclasses. The binding activity in all individuals reached a maximum between 2 and 4 weeks after the injection. The antibody activity in the serum of four individuals whose serum gave weak IgG binding was confined to IgG1. Two individuals did not show any IgG binding activity at all. In the ten persons with a positive IgE-RAST and three of the normal individuals, who also had a positive IgE-RAST, the distribution of the antibodies over the subclasses was the same as in the others.