A procedure is described for immunizing in vitro and stimulating proliferation of specific B-cell lymphocytes. The method is applicable to production of monoclonal antibodies against proteins that are soluble only in denaturing solvents. An induction period is described in which antigen is presented to the B-cell population in the absence of serum. Also, antigen is coupled to mitogenic silica, which allows the effective presentation of both soluble and insoluble antigens. The results indicate hybridomas can be obtained that secrete IgMs directed against highly conserved or weakly immunogenic antigens.