Antigen-presenting macrophages (MΦ) were derived from day 7 cultures of bone marrow stem cells using L cell conditioned medium. The adherent bone marrow-derived macrophages (BMMΦ) were 100% esterase-positive, 95% positive for C3 receptors, 93% positive for Fc receptors, and 95% actively phagocytic. Indirect immunofluorescence using anti-Ia monoclonal antibodies resulted in 60% Ia-positive BMMΦ on day 7 of stem cell culture. BMMΦ could stimulate mixed lymphocyte reaction (MLR) proliferation across an I-A subregion difference, but not across I-J subregion differences. This contrasted with splenic MΦ which stimulated MLR proliferation across both an I-A and I-J subregion difference. The apparent lack of I-J subregion determinants on BMMΦ correlated with their ability to function as antigen-presenting cells. In these experiments, BMMΦ effectively reconstituted the trinitrophenyl-specific IgM plaque-forming cell (PFC) response of B cells but not the primary burro red blood cell (BRBC)-specific IgM-PFC response of MΦ-depleted spleen cells. When BMMΦ were added to BRBC-primed T and B cells, they reconstituted the secondary IgG PFC response to levels obtained using splenic MΦ. These experiments relate the differential expression of H-2I region determinants on antigen-presenting cells with their functional capacity.
ASJC Scopus subject areas
- Immunology and Allergy