Bone marrow macrophages induced to antigen presentation by lymphokines interact selectively with distinct T cells

In vitro matured bone marrow-derived macrophages (BMM phi), which represent a pure population of M phi, were shown to act as antigen-presenting cells (APC) to the T cell clone ST2/K.9. This interaction was major histocompatibility complex restricted. Upon long-term culture in macrophage colony-stimulating factor, BMM phi were activated for antigen presentation by a 48-h pulse with lymphokine-containing supernatant of concanavalin A-stimulated rat spleen cells (Con A sup). The capacity of such activated M phi to function as APC decreased upon removal of Con A sup, and could be regenerated by a second pulse. This finding suggests that antigen presentation by mature M phi is a reversible function regulated by T cell factors. When the responsiveness of various T cell lines to antigen presented on BMM phi or spleen cells was compared, distinct activation requirements were observed for different T cells since lymphokine-activated BMM phi were not capable of inducing antigen-specific proliferation of all lines.