Antigen-specific helper factor was induced in vitro from lymphoid cells of monkeys and mice by using an antigen derived from Streptococcus mutans. Helper activity was removed from supernatants of monkey cells by affinity chromatography on Sepharose 4B insolubilized antibodies specific for human beta 2-microglobulin (H beta 2M) prepared in chicken, rabbit and rat, and an insolubilized monoclonal mouse anti-H beta 2M antibody-bound monkey helper factor activity. However, guinea pig antibody to ...