ACETYLCHOLINESTERASE-INDUCED RESPIRATORY BURST IN MACROPHAGES - EVIDENCE FOR THE INVOLVEMENT OF THE MACROPHAGE MANNOSE-FUCOSE RECEPTOR

It has long been suggested that acetylcholinesterase is capable of fun ctioning in a non-cholinergic manner. However, very little is known ab out the molecular structures which mediate the interaction between thi s protein and the cellular membrane. Previously it was demonstrated th at acetylcholinesterase interacted in a carbohydrate-specific manner w ith peritoneal macrophages and induced the 'respiratory burst' [1]. Th is study aimed to establish whether a carbohydrate-binding site exists on the acetylcholinesterase molecule itself, or alternatively, whethe r the macrophage carbohydrate-binding receptor is involved. No carbohy drate binding properties intrinsic to acetylcholinesterase were detect ed using affinity chromatography with immobilised monosaccharides, ery throcyte agglutination and gel-diffusion techniques. The interaction b etween acetylcholinesterase and several monosaccharide columns observe d in this study appeared to be due to ionic interactions. Moreover, it was shown that a specific inhibitor of the enzymatic activity of AChE , BW284C51, could inhibit the peritoneal cell response not only to ace tylcholinesterase, but also to several other stimuli, thus exhibiting a non-specific effect on macrophages. However, the inhibitory effects of specific ligands of the macrophage mannose-fucose receptor and the inability of non-glycosylated acetylcholinesterase to interact with ma crophages suggested that the effect of acetylcholinesterase on periton eal cells is most probably mediated by the macrophage mannose-fucose r eceptor. The role of the mannose-fucose receptor in triggering the res piratory burst response was supported by the fact that several ligands of these receptors were capable of inducing the functional response o f macrophages.