Sugar specificities of anti-human ABO(H) blood group erythrocyte agglutinins (lectins) and haemolytic activity in the haemolymph and gut extracts of three Glossina species

Relatively heat-labile, human ABO(H) blood group non-specific lectins or lectin-like agglutinins, titre range 2-9-2-16, were detected in Glossina morsitans morsitans, Glossina palpalis gambiensis and Glossina tachinoides haemolymph. The haemagglutinins exhibited wide specificities for carbohydrate residues on the surface of human erythrocytes, indicative of heterogeneity, which varied according to the tsetse species examined and the type of erythrocyte used. Haemolymph agglutinin reactivities were directed mainly towards sorbose, trehalose, glucose, 2-deoxygalactose and to a lesser extent the deoxy, [1-4]- and/or [1-6]-linked derivatives of glucose. Occasionally fructose, mannose, sucrose, turanose, stachyose and melezitose minimally inhibited agglutination. Midgut haemagglutinins, titres 2-6 or 2-7, were only found in G. m. morsitans exclusively against "AB" erthrocytes whilst hindgut extracts in all threee Glossina species caused agglutination (titres 2-1-2-7) of most erythrocyte types. Heat-labile, possibly protease but not trypsin, haemolytic molecules were present in most gut preparations. Conversely, a non-proteolytic, partially thermostable haemolysin(s) was detected in G. m. morsitans midgut samples. Gut haemagglutinin specificities were less diverse than those of haemolymph and effective agglutination inhibitors were glucose, galactose or mannose and their deoxy, aminated and N-acetylated derivatives. Additionally sorbose, sucrose, turanose, gluconic acid and methyl glucoside inhibited in G. m. morsitans. Both agglutinin and lytic activities were either negated or reduced following freezing and thawing treatments of gut extracts and haemolymph.