Concentration and composition of gangliosides and neutral glycosphingolipids of adult human lung, and lung small cell carcinoma were studied. The structures of the glvcolipids were determined by quantitative component determination, enzymic degradation, permethylation and fast atom bombardment mass spectrometry. Adult human lung contained mainly gangliosides with lactosylceramide as the basic core, G M3 , G D3 and G T3 , and approx. equal proportions (10%) of gangliosides of the gangliotetraosyl- and lactotetraosylceramide series. 18 gangliosides with different carbohydrate moieties were identified: four of them were only found in the tumor tissue. The adult human lung contained 85 nmol (77–120) gangliosides and 140 nmol neutral glycosphingolipids per g wet weight. Globoside was the major neutral glycolipid and there were only minor amounts of glyolipids of the lactotetraose series. In small cell carcinoma tissue the concentration of neutral glycosphingolipids was approximately twice as high than in normal lung tissue, and there was a markedly larger concentration of both lactosylceramide and glvcolipids of the lactotetraose series and fucose derivatives of these. The concentration of gangliosides varied between 202 and 415 nmol per g wet weight. Compared to normal lung tissue, the tumor tissue had a lower proportion of G D3 , and a higher proportion of complex gangliosides, and they contained five tumor-associated gangliosides: Fuc-G M1 , Fuc-G D1b , 3'-L M1 , Fuc-3'-L M1 and 6'-nL M1 .
