Incorporation of staphylococcal alpha-toxin in glutaraldehyde fixed erythrocytes

The incorporation of staphylococcal alpha-toxin into glutaraldehyde fixed erythrocytes occurs in the same way as with native erythrocytes. Binding of alpha-toxin to the cells is accompanied by oligomerization of native 3 S toxin to the membrane-bound 11 S toxin hexamer, which is embedded into the lipid bilayer of the membrane. Antibodies against alpha-toxin, build up during an infection with S. aureus, can be determined in a passive hemagglutination test (IHT) using glutaraldehyde fixed and alpha-toxin treated erythrocytes. To test the validity of this IHT, antibodies to alpha-toxin were determined in 550 human sera of patients from hospitals of the University of Giessen suspected to suffer from staphylococcal infections and in 300 sera of healthy blood donors. The results were compared with the titres obtained by a convenient neutralisation test (ASTA). All sera with elevated titres in the ASTA test also showed high titres in the IHT. Because it is simple to perform and highly reproducible, the IHT seems to be a valuable test for detection of antibodies against staphylococcal alpha-toxin.