| Abstract: | Normal human alveolar macrophages (AM) significantly and reproducibly suppress induction of IL 2-activated killer (LAK) cell activity against allogeneic Burkitt's lymphoma (Daudi) cells. Incubation of purified peripheral blood lymphocytes for 4 days with autologous AM and 1 U/ml of IL 2 resulted in AM-mediated suppression of LAK activity, whereas peripheral blood monocytes isolated freshly by centrifugal elutriation from the same donor potentiated induction of LAK activity by IL 2. The suppression of LAK cell induction by human AM was dependent on the density of AM added to the lymphocyte cultures. Recombinant IFN-gamma did not affect AM-mediated suppression of LAK cell induction by IL 2. Both AM and monocytes stimulated with lipopolysaccharide markedly suppressed LAK cell induction by IL 2. AM-mediated down-regulation was seen only when AM were added immediately after the start of incubation of lymphocytes with IL 2; AM potentiated LAK activity when added 1 day later. Similar AM-mediated suppression of LAK cell induction was observed with four lines of allogeneic lung cancer cells as targets for LAK activity. These results indicate that AM may be important in regulation of in situ induction of LAK activity in the lung. |
