To verify if the small bowel mucosa was able to produce NFR antibodies, duodenal mucosa samples were obtained from the 11 patients in group 1 who, after a reasonable period on a GFD, agreed to undergo a second upper endoscopy with biopsy sampling. The culture medium, prepared with 17 ml RPMI-1640 medium, 3 ml fetal calf serum (FCS), 0·2 ml l-glutamine (200 mM), 2 ml penicillin (10 000 UI/ml)–streptomycin (10 000 µg/ml) and 0·04 ml gentamycin (10 mg/ml) (Gibco

/Invitrogen, Carlsbad, CA, USA), was stabilized preventively at pH 7·4 and was then sterilized by filtration with a 0·22 µm pore size filter (Sigma). The duodenal mucosa samples, washed Selleck INCB024360 first in physiological solution (NaCl, 9 g/l), were placed into sterile tubes containing 500 µl of medium and then cultured, with and without a peptic–tryptic digest of gliadin BYL719 (PT–gliadin; 1 mg/ml), at 37°C from 30 min

to 48 h. Thereafter, supernatants were collected and stored at −70°C until tested. All operations were performed in a sterile environment. Total IgA, IgA1 and IgA2 EMA/NFR antibodies were evaluated in undiluted culture supernatants by indirect IFA on monkey oesophagus sections (Eurospital), as described for sera. The human colorectal cancer cells Caco2 were cultured in Dulbecco’s modified Eagle’s medium (DMEM) supplemented with 10% FCS, 2 mM l-glutamine, 100 U/ml penicillin and 100 µg/ml streptomycin (Gibco /Invitrogen) under 95% air and 5% CO2, at 37°C up to cell confluence. Subsequently, cells were washed twice in phosphate-buffered saline (PBS) Branched chain aminotransferase to remove culture medium-derived proteins and total cell proteins were extracted by incubation with a TNE extraction buffer [50 mM Tris/HCl at pH 7·8, 150 mM NaCl, 1 mM ethylenediamine tetraacetic acid (EDTA), 1% TRITON X-100] containing

protease inhibitors on ice for 30 min. Extracted total cell proteins were collected and stored at −70°C until used. The cytosolic and nuclear protein fractions of Caco2 cells were prepared by a standard method. Briefly, after Caco2 cell culture and washing, the cell pellet was resuspended in 3 ml RBS medium [10 mM Tris/HCl at pH 7·4, 10 mM NaCl, 1·5 mM MgCl2, 1 mM phenylmethylsulphonyl fluoride (PMSF)] and incubated on ice for 10 min. Cells were broken by incubation with NP-40 and Na-Deoxicholate detergents (0·5% and 0·15%, respectively), on ice for 30 min. Thereafter, cells were homogenized with a glass–glass potter and the homogenate was centrifuged (800 g for 10 min) at 4°C. The supernatant representing the cytosolic protein fraction was collected and stored at −70°C until used. The pellet containing the crude nuclear protein fraction was resuspended in 3 ml RBS medium and centrifuged (1000 g for 30 min) through a sucrose cushion (30% sucrose in RBS medium) at 4°C.