Intestinal titres of anti‐tissue transglutaminase 2 antibodies correlate positively with mucosal damage degree and inversely with gluten‐free diet duration in coeliac disease

Summary It has always been known that anti‐tissue transglutaminase 2 (anti‐ TG 2) antibodies are produced in the small intestine. Their serum titres correlate with mucosal damage degree and decrease on a gluten‐free diet ( GFD ). We aimed to correlate intestinal anti‐ TG 2 antibodies levels with degree of mucosal damage and GFD duration. Thirty‐four active, 71 potential and 24 CD patients on GFD for at least 2 years were enrolled. Anti‐ TG 2 deposits were detected in intestinal biopsies by double immunofluorescence. Biopsies were cultured for 24 h with medium, and with gliadin peptic tryptic digest ( PTG ) or A‐gliadin peptide 31–43 ( P 31‐43). Anti‐ TG 2 antibodies secreted into supernatants were measured by enzyme‐linked immunosorbent assay ( ELISA) . All active CD patients secreted high titres of anti‐ TG 2 antibodies into culture medium that increased with the worsening of mucosal injury (Spearman's r  = 0·71; P  < 0·0001). Seventy of 71 potential CD patients and 15 of 24 treated CD patients secreted low titres of anti‐ TG 2 antibodies into supernatants, eight of nine negative treated patients being on GFD for more than 10 years. An inverse correlation between antibody titres and duration of GFD was found, (Spearman's r  = −0·52; P  < 0·01). All active, 53 of 71 potential and six of 24 treated, CD patients showed anti‐ TG 2 mucosal deposits. Five of six positive treated CD patients had been on GFD for fewer than 6 years and were also positive for secreted anti‐ TG 2. In treated patients, PTG /P31‐43 was not able to induce secretion of anti‐ TG 2 antibodies into culture medium. Measurement of anti‐ TG 2 antibodies in biopsy supernatants proved to be more sensitive than detection by immunofluorescence to reveal their intestinal production. Intestinal anti TG 2 antibodies titres correlated positively with the degree of mucosal damage and inversely with the duration of GFD .