Patients were informed about the aim of the study and gave their full consent. The study was approved by the Ethical Committee of

Department of Pediatrics, University Federico II, Naples. The serum level of endomysium (EMA) and tissue transglutaminase (anti-tTG) antibodies [immunoglogbulin (Ig)A] was measured immediately before both gluten challenges started (day 0). EMA were detected by indirect immunofluorescence on frozen sections of human umbilical cord and anti-tTG using the enzyme-linked immunosorbent assay (ELISA) technique with a commercial kit (Eu tTg IgA; Eurospital, Trieste, Italy). Results were interpreted according to the manufacturer’s instructions: negative <9 U/ml, weak positive in the range 9–16 U/ml, selleck kinase inhibitor positive >16 U/ml. Patients ate 200 g of wheat bread or cookies daily for 3 days, corresponding to about 12 g of gluten per day (first challenge). After a wash-out of 3–10 months on a strict gluten-free diet, 13 of 14 coeliacs consumed wheat for an additional 3 days (second challenge). At the time of the first gluten challenge, 11 patients were seronegative for EMA or anti-tTG and three had low antibody titres. Two patients complained about abdominal pain on the first day of the challenge, but they did not stop the gluten intake. The remaining patients reported no symptoms. A commercial wheat flour was used for baking the bread and

cookies. Gliadin was extracted according to Wieser selleck chemicals llc et al. [20] and digested enzymatically with pepsin and trypsin, as described previously [21]. The 33-mer (α-gliadin 57–89) peptide was synthesized by solid-phase automated flow, as described elsewhere [2]. Both PT-gliadin (indicated hereafter as gliadin) and peptides were deamidated with guinea pig tTG, as reported elsewhere [2]. Venous blood (15–20 ml) was collected in a heparizined syringe before (day Interleukin-3 receptor 0) and 6 days after (day 6) the gluten challenge. Peripheral blood mononuclear cells (PBMCs) were isolated by Ficoll-Paque density centrifugation. PBMCs were analysed immediately for antigen recognition by IFN-γ ELISPOT assay, as described previously [22]. Briefly, 4 × 105 PBMCs were seeded in 200 µl

of complete medium X-Vivo15 supplemented with 5% heat-inactivated AB pooled human serum, 1% antibiotics (100 U/ml penicillin and 100 µg/ml streptomycin) and 1% L-glutamine (2 mM) (all provided by BioWhittaker, Verviers, Belgium) in duplicate in 96-well plates (Millipore, Bedford, MA, USA) coated with purified anti-human IFN-γ antibody (MabTech, Nacka Strand, Sweden). Gliadin, either deamidated or native, was tested at 50 µg/ml and 33-mer peptide at 30 µg/ml (7·7 µM). Cells were incubated for 36–40 h with biotinylated anti-human IFN-γ antibody (MabTech) followed by incubation with streptavidin horseradish peroxidase (HRP) (BD-Pharmingen, San Diego, CA, USA). Spot-forming cells (SFC) were counted by an immunospot analyser (A.EL.