ABSTRACT
In 1888 Stillmark reported hemagglutinating activity in castor bean extracts. This activity was produced by carbohydrate-binding proteins, later defined as lectins. In 1908, G. Guyot found that Escherichia coli possessed hemagglutinating activity. The hemagglutination (HA) test has mostly been used for detection and characterization of pili, often with a set of erythrocytes from different animal species. The search for carbohydrate receptors for the known range of pili has been conducted mainly with hemagglutination inhibition (HAI) tests, using mono- and disaccharides, glycolipids, and mucins. Bacterial strains were grown on solid media. Hemagglutination at differing pH and ionic strength was tested with erythrocytes fixated with glutaraldehyde. K99 strains gave HA of sheep and human erythrocytes, while colonisation factor antigen (CFA/I) agglutinated only human erythrocytes. However, the human erythrocyte HA was strong with both K99 and CFA/I. Gangliosides have been shown to be receptors for several bacterial toxins and for hormones, interferon and lectins. Gangliosides may serve as receptors for gonococcal pili.
