The susceptibility of the mouse immunoglobulin subclasses to suppression by high doses of antigen

Using the coprecipitation technique and rabbit antisera specific for mouse IgG1, IgG2a, IgG2b, IgA and IgM, the responses of BALB/c mice to a wide range of doses of human serum albumin have been studied. Antibody activity was detected in all five classes. At lower doses, below 1 mg, the distribution of antibody activity among the immunoglobulin classes was fairly constant, but at higher doses a decrease in antibody activity occurred in certain subclasses only, particularly IgG1. The actual effect obtained depended on whether the antigen was given with or without Bordetella pertussis. To study the subclass suppression further, mice were also subjected to neonatal treatment with soluble antigen. The suppression here was again mainly in the thymus-dependent IgG1 subclass.