MACROPHAGE-COLONY STIMULATORY FACTOR-ACTIVATED BONE-MARROW MACROPHAGES SUPPRESS LYMPHOCYTIC RESPONSES THROUGH PHAGOCYTOSIS - A TENTATIVE IN-VITRO MODEL OF ROSAI-DORFMAN DISEASE

NBXFO hybridoma cells produced macrophage colony-stimulating factor (M -CSF), which stimulated the growth of murine bone marrow-derived macro phages with potent suppressor activity, These macrophages suppressed l ymphocyte responses to mito gens and antigens in a dose-dependent mann er, Using a transwell chamber, we demonstrated that macrophages needed physical contact with the lymphocytes to suppress lymphocyte prolifer ation on day 1 in the concanavalin A mitogen reaction, In addition, no soluble suppressor factor was detected at that time, The number of ly mphocytes disappeared with time when they were cocultured with the mac rophages. Electron microscopy revealed that the macrophages phagocytos ized the lymphocytes after 7 1/2 h. Dextran sulfate, heparan, and fuco idan prevented the macrophages from suppressing the lymphocytes, This phenomenon resembles the human disease sinus histiocytosis, also calle d Rosai-Dorfman disease, in which macrophages (histiocytes) phagocytos ize autologous lymphocytes; occasionally, this disease is associated w ith immunological abnormalities, Thus we believe that macrophage-activ ating cytokines, such as M-CSF, may stimulate macrophages to phagocyto se lymphocytes in vivo.