Suppressor adherent phagocytic cells in solid tumors: a postulated escape mechanism

A localized graft-versus-host reaction was used to assess the cellular immunity of mice supporting progressive growth of an allogeneic tumor. It was found that early in tumor development anti-tumor-cellular-mediated immunity was hyper-responsive, and that adherent phagocytic cells isolated from the neoplasm would inhibit the specific immunological response. Based on these observations and indirect inference it was postulated that a major factor in the success of an immunogenic tumor is the coterminous development of a normal adherent phagocytic cell population which specifically nullifies, in situ, cellular-mediated anti-tumor immunity.