Monoclonal antibodies against human thyroglobulin were generated using splenocytes cultured in vitro with the antigen. When splenocytes from non-immunized mice were used, about 90 % of the hybridomas obtained produced immunoglobulins of the IgM class. In contrast, when splenocytes from mice previously immunized in vivo with human thyroglobulin were cultured in vitro with the antigen about 85 % of the hybridomas obtained produced immunoglobulins of the IgG class. The properties of the monoclonal antibody produced by hybridoma 3D12, obtained after culturing splenocytes from non-immunized mice with human thyroglobulin, were examined in detail. Monoclonal antibody 3D12 reacted only with human thyroglobulin and not with the murine homologue in an enzyme-linked immunosorbent assay, in immunoblotting experiments and in an immunohistochemical test. These results provide direct evidence that a primary response to an antigen can be elicited by adding the antigen to cultures of splenocytes from non-immunized mice.
