ANTIBODIES DIRECTED TO ANTIGENS SECRETED BY MURINE EPITHELIOID MACROPHAGES MODULATE BCG-INDUCED GRANULOMATA

THE authors have previously shown that epithelioid cells isolated from mice secrete a factor, called macrophage deactivating factor (MDF), t hat promptly deactivates superoxide release by activated macrophages a nd neutrophils. In this paper some biological properties of a polyclon al rat antiserum directed to MDF and other substances secreted by thes e cells are described. The immunoglobulin fraction of this antiserum r eacted, by immunocytochemical methods, with epitopes in the cell membr ane of macrophages adherent to coverslips subcutaneously implanted for 14 days; but not for 5 days. It also reacted with antigens within and outside cells in BCG-induced granulomas. This antiserum blocked compl etely the macrophage deactivating activity of epithelioid cell culture supernatants. Anti-IL-10 monoclonal antibody, did not block MDF activ ity. The administration of the immunoglobulin fraction from immunized rats to C5 deficient mice bearing BCG-induced granulomatas in the foot pad, significantly reduced the size of the lesions. A marked necrosis of inflammatory cells and mononuclear cells phagocyting debris of necr otic cells were observed in these lesions.