Cell surface carbohydrates: molecules in search of a function?

I N T R O D U C T I O N “Many knowledgeable biologists would say, almost reflexly, that complex carbo­ hydrates probably play a pivotal role in determining the specificity of many biological recognition phenomenon” (Marchesi, Ginsburg & Robbins, 1978). So states the preface to an authorative symposium volume on surface carbohydrates. However, 16 years previously it was possible, in the light of contemporary knowledge, for a discussant at an equally authorative symposium to state, in relation to the recognition of self and non-self, “At the cell level it is possible that carbohydrate may play a part, carbohydrate is always present, but I know of no clear evidence yet to indicate that it plays a role in the mechanism by which cells discriminate between their closer and more distant relatives” (Davies, 1963). Clearly over this period, which incidentally corresponds very closely with the establishment of the Journal of Cell Science, a considerable development in the study of surface carbohydrates has taken place, though interestingly there is still a need for definitive evidence for the role of carbohydrates in cell discrimination. Rothstein (1978) drew attention to the fact that when the membrane literature was reviewed in the Annual Review of Physiology in 1968 about 400 of an estimated 600 published references were used, among which papers on glycoproteins, perse, were not a recognizable category. However, between 1968 and 1976 the annual rate of production of papers on membranes jumped from about 600 to 3000, of which in 1976, 300 papers were identifiable as being concerned with proteins and glyco­ proteins. The pace of research into glycoproteins in particular continues unabated, with Sharon quoting in 1984 that since 1976 over 20000 papers have been published on these compounds. In being invited to make a contribution to this twentieth anniversary volume of the Journal it is perhaps appropriate to step back and look at the way in which an interest in surface carbohydrates has developed and to examine the body of work started in the 1960s, which has resulted in this quantum jump in endeavour, before going on to speculate on the direction that this area of research is likely to take in the next 2 0 years.