Previous studies have suggested that various A-gliadin-derived peptides actively agglutinate K562CS) cells. These active peptides showed the following common sequences: pro-ser-gln-gln and gln-gln-gln-pro. In this study, we have synthesised and tested the following toxic fragments: the peptide with the 31–55 amino acid sequence, which contains both the toxic sequences, and the peptides 31–43 and 44–55, which contain the sequences gln-gln-gln-pro, and pro-ser-gln-gln, respectively. Both the peptides with either the gln-gln-gln-pro or pro-ser-gln-gln sequences were active in agglutinating all cells. However, the peptide 44–55 agglutinated 100% of the cells at a concentration two times greater than the peptide 31–43. This suggests a relationship between the gln-gln-gln-pro and pro-ser-gln-gln sequences and the damaging effect of gliadins on the coeliac small intestine in individuals affected by coeliac disease. Moreover mannan and oligomers of N-acetylglucosamine were found to be able to prevent the cell-agglutinating activity of the active peptides.
