IgG and IgA diphtheria antitoxin responses from human tonsil lymphocytes

Human tonsil lymphocytes were stimulated with diphtherin toxoid, and then cultured in a Marbrook culture system so that antibodies could be measured in the culture supernatant. Specific antibodies were measured with excess radiolabeled antigen and antisera specific for each immunoglobulin class. Good IgG and IgA diphtheria antitoxin responses were obtained and responding culture supernatants were shown to neutralize toxin. The relationship between antitoxin response in vitro, and immunization of donors with toxoid was investigated. It was found that at least 2 immunizations after the age of 6 mth were necessary to prime the tonsils for an vitro antibody response. IgG and IgA in culture supernatants were demonstrated by immunodiffusion, and were measured by radioimmunoassay. By sucrose density gradient ultracentrifugation, it was shown that 40% of the IgA produced in the cultures was greater than 7S. Evidence was obtained that neither the IgA nor the specific IgA antitoxin bears a secretory piece. It appears that human lymphocytes from tonsils produce polymer IgA in vitro without a secretory piece.