B Cells As Antigen-presenting Cells: Antibody Production in Vitro Against a T-dependent Antigen

It was examined whether B cells can serve as antigen-presenting cells (APC) in the antibody response to a T-dependent antigen, trinitrophenyl-ovalbumin (TNP-OVA). B cells purified from mice primed with TNP (TNP-B cells) responded to TNP-OVA in the presence of purified T cells sensitized with OVA (OVA-T cells). OVA-T cells required the addition of APC to proliferate in response to TNP-OVA. APC activity of TNP-B cells in the T-cell proliferation was abolished by 4000 R irradiation. Our experiments also revealed that an antibody response requires more adherent cells than the T-cell proliferation. These results indicate that adherent cells possibly accompanying the T- and B-cell preparations were at a less than functional level. There was genetic restriction between T and B cells for the antibody response. B cells in the pellet fraction of 70% Percoll density sedimentation behaved similarly to the unfractionated TNP-B cells in the antibody response. A T-cell clone specific for human gamma-globulin (HGG) also induced an anti-TNP antibody response in B cells from unprimed mice in the presence of TNP-HGG. These results suggest that B cells are able to elicit an antibody response to a T-dependent antigen in the presence of carrier-primed T cells without the participation of macrophages.