Human IgG and IgA Diphtheria Antitoxins in Serum, Nasal Fluids and Saliva

The site of production of γA and γG in human nasal fluids was investigated by measuring antibody responses to diphtheria toxoid injected parenterally or given topically as nose drops. The amount of radioactive toxoid combined with γA or γG was measured separately by precipitating the immonoglobulin from serum or exocrine fluids with rabbit antisera specific for each immunoglobulin class. That this measurement reflected the amount of each class of antibody present was shown by its correlation with neutralization titers and by measurements of antibody avidities. The bulk of γA antitoxin in nasal fluids was demonstrated to be 11 S, exocrine γA by its elution characteristics from Sephadex G-200 and by its reaction with antibody to secretory piece. Comparisons of γA and γG antibody levels found in serum, nasal fluids, saliva and sputum after parenteral or topical administration of toxoid indicated that most nasal fluid γA and some of the nasal fluid γG were made locally in response to local antigenic stimulation.