Comprehensive 10-year Strategy for Cancer Control fi'om the Ministry of Health and Welfare of Japan, a grant for cancer research from the Ministry of Education, Science and Culture

Lung macrophages (LM)' are known to differ f rom peri toneal macrophages (PM) in many respects, such as their lysosomal enzymes, metabol ic activity for ene rgy requ i rement , morphology , and function (1-3). We repor t ed that the expression of a glycosphingolipid, asialo GM1, on the cell surface is markedly di f ferent be tween LM and PM (4, 5). In the present paper , we repor t that LM are unresponsive to activation for t u m o r cytotoxicity by bacterial l ipopolysaccharide (LPS), while PM f rom the same strains o f mice were responsive, because o f the lack o f binding with LPS on the cell surface o f LM. T h e LPS-binding sites appea r af ter t r ea tmen t of LM in vitro with a lymphokine-r ich superna tan t or r ecombinan t mur ine g a m m a in te r fe ron (IFN-y), result ing in recovery o f responsiveness to activation by LPS.