IN-VITRO TOXICITY OF PURIFIED GLUTEN PEPTIDES TESTED BY ORGAN-CULTURE

Various subfractions of Frazer fraction III were separated by high-pre ssure liquid chromatography, and their toxicity in vitro (organ cultur e) was tested in comparison with alpha-gliadin using duodenal biopsies from 25 patients with active celiac disease and subtotal villous atro phy, 2 patients with partial villous atrophy, and 10 nonceliac control s. One dominating fraction, designated Frazer III-2-VIII, was purified by several steps of rechro-matography. It was markedly toxic to duode nal explants from patients with active celiac disease. The mean entero cyte height after culture was 15.9 mu m compared with 25.6 mu m in glu ten-free medium. This difference was statistically significant in all cases except one, in which the lowest concentration (110 mu g) was use d. The in vitro toxicity of Frazer III-2-VIII was comparable with the toxicity of cr-gliadin in twofold to fivefold higher concentrations. N o toxicity could be detected in nonceliac explants (mean enterocyte he ight, 25.7 vs. 24.9 mu m in gluten-free medium). The N-terminal amino acid sequence was (Gin)Ile- n-Vlr-Gln-(Trp)-Pro-Gln-Gln-(Gln)-Gln-Pro- Phe-Pro- . This sequence was not homologous to previously reported seq uences of toxic gluten peptides. By use of the SwissProt and GenEMBL d atabases, it was concluded that the peptide Frazer III-2-VIII is part of the gamma-gliadin fraction.