Accessory cell function of cells of the mononuclear phagocyte system isolated from mycobacterial granulomas

Epithelioid cells from BCG-induced granulomas and macrophages from Mycobacterium leprae-induced granulomas were examined for their ability to act as accessory cells for T-cell proliferation to mitogen (Con A) and antigen (PPD). The granuloma cells were separated on a FACS using monoclonal antibody specific to guinea pig macrophages. Epithelioid cells (which are Ia negative) were able to support proliferation to Con A but not to antigen. Cultures containing Ia positive granuloma macrophages from M. leprae sensitized animals did not show responsiveness to Con A or to PPD. Oil-induced peritoneal exudate macrophages from BCG or M. leprae immunized animals were able to act as accessory cells for both mitogen and antigen proliferation. The nonresponsiveness of cultures containing epithelioid cells stimulated with PPD or M. leprae granuloma macrophages stimulated with Con A was not due to suboptimal or supraoptimal accessory cell:lymphocyte ratios.