Studies of in vitro γ-interferon production in coeliac disease as a response to gliadin peptides

The effects of certain fractions of a peptic-tryptic-pancreatinic (PTP) digest of wheat gliadin of synthetic peptides on the production of gamma interferon (γ-IFN) in cultures of whole blood from adult patients with coeliac disease (CD) have been studied using a sandwich enzyme immunoassay. The most active peptides were fraction 9, its two principal sub-fractions (sub-fractions 1 and 2) and a synthetic peptide of sequence RPQQPYPQPQPQ (peptide V) corresponding to the principal peptide obtained from reversed-phase HPLC of fraction 9. Results with blood from the control group of subjects also indicated some response to these antigens, in most cases at similar levels to those observed with the coeliacs. Fraction 1 of the PTP digest and the other nine synthetic peptides tested were inactive with both coeliacs and controls. These results are in agreement with the results of in vivo and in vitro toxicity tests. They provide evidence of a link between toxicity and cell-mediated immune response in CD, and suggest that peptide V represents one of the active parts of the gliadin molecule.     

Partial purification of somatomedin from human plasma.

Fractional precipitation of human plasma using ethanol, followed by chromatography on S.P. Sephadex, yielded a somatomedin-enriched fraction freed from substantial amounts of inhibitory substances. Heat coagulation of the proteins present in this fraction allowed the recovery of appreciable amounts of active components which were then chromatographed on Sephadex G-75 and S.P. Sephadex. A major part of the activity was associated with components less than 4,000 daltons, suggesting that somatomedin, or an active fragment thereof, had been dissociated from a carrier protein by the heat treatment. The range of pH employed throughout was 5.3-9.8. Recoveries of about 30% of biological activity with fold-purification up to 38, as measured by radioactive sulphate uptake in the chick pelvic cartilage assay, were higher than those obtained using acid-ethanol extraction.