Delayed-type hypersensitivity induced by antigen-pulsed, bone marrow-derived macrophages.

Mouse bone marrow cells, cultured in specifically conditioned medium, were found to be virtually pure macrophages after 7 days. When pulsed with antigen, these cells induced and elicited delayed-type hypersensitivity (DTH) with the same efficiency and major histocompatibility complex restrictions as antigen-pulsed peritoneal exudate cells. Both of these macrophage populations had 20% Ia+ cells, as measured by complement-mediated cytotoxicity. When most of the Ia+ cells were removed, the remaining antigen-pulsed macrophages could not elicit DTH in sensitized mice.