Immunologically Specific Activation of Macrophages Armed with the Specific Macrophage Arming Factor (SMAF) 1

Summary

A specific macrophage arming factor (SMAF) is produced in the culture supernatant of sensitized spleen cells incubated with the specific antigen. Macrophages armed with a SMAF directed to a transplantation or tumor specific antigen specifically inhibit the growth of tumor cells bearing this antigen. This study shows that if SMAF-armed macrophages are exposed to the specific antigen in vitro they become capable of growth inhibiting lymphoma cells in a nonspecific way. This change induced by the specific antigen is referred to as activation. Activation is also observed if mouse macrophages are armed with SMAF directed against sheep red cells. However, the culture supernatant obtained by incubating BCG-sensitized spleen cells with BCG organisms activates macrophages directly possibly because it contains both SMAF and the specific antigen.