In vitro Stimulation of Presensitized Mouse Spleen Cells with Poliovirus Type 1, Mahoney, and Enhancement of Poliovirus-specific Hybridomas

In vivo immunization of BALB/c mice with poliovirus type 1, strain Mahoney, or with its purified polypeptides resulted in 0.2 to 0.5 antigen-specific hybridoma microcultures per 10(6) spleen cells. Stimulation of spleen cells from mice immunized with poliovirus or with its polypeptides in vitro with poliovirus 6 days prior to fusion with the myeloma cells led to a six- to 20-fold increase in the number of positive microcultures, i.e. after stimulation the yield of poliovirus-specific hybridomas was up to 3.8 antigen-specific microcultures per 10(6) spleen cells. The in vitro stimulation of spleen cells primed in vivo was demonstrated by the detection of poliovirus-specific antibody-producing cells 6 days after in vitro cultivation in the presence of poliovirus as antigen. Only spleen cells stimulated under these conditions in vitro gave rise to specific antibody-producing cells and yielded antigen-specific hybridomas after somatic hybridization.