GANGLIOSIDES CAN ACTIVATE HUMAN ALTERNATIVE COMPLEMENT PATHWAY

The alternative complement pathway (ACP) in vertebrates is known to be important in inflammatory reactions, and to be activated by foreign s ubstances such as bacterial lipopolysaccharide (LPS) and zymosan. alth ough to date no intrinsic activators have been identified except compl ement receptor type 2. From the point of the structural similarity of LPS to ganglioside, we have investigated gangliosides which are abunda ntly present in animal cells for their activity on the human ACP. All of seven gangliosides tested were found to activate this pathway in a manner depending on the number of sialic acids and neutral sugars cont ained in the molecules. A dose - response study suggested a correlatio n of the threshold in ganglioside concentration with its critical mice lle concentration. Gangliosides may thus serve as an intrinsic activat or for ACP in animals, thereby leading to inflammation. The possibilit y of the participation of sialidase in complement activation is also d iscussed.