However, further investigations are necessary to understand the biological significance of this finding. The nuclear nature of NFR-related 65- and 49-kDa antigens has been evidenced by cell fractionation experiments. In fact, sera collected from CD patients when NFR antibodies are observable show IgA reactivity in total cell protein extract and in its nuclear fraction that is absent in the cytosolic fraction. Serum IgA reactivity with 65- and 49-kDa antigens has been detected on lysates of the human Caco2 cell Ku 0059436 line, and is therefore definable as autoimmune. Moreover,

we also show that this autoreactivity is gluten-dependent, and therefore related strictly to CD. Indeed, it is present in CD patients’ sera up to NFR antibodies are observable and disappear on a GFD, with the clearance Torin 1 of NFR antibodies themselves. Circulating autoantibodies CD patients provide an important tool in screening, diagnosing and monitoring the disease. In detail, serum EMA and anti-tTG antibodies are used currently in clinical practice on account of their high sensitivity and specificity [16,17]. Furthermore, serum EMA disappear upon the mucosal healing subsequent to a GFD [21],

while after gluten reintroduction into the diet their reappearance may predict mucosal relapse [28]. The kinetics of EMA, however, is not well known and it is not investigated widely. In the present study, we show that EMA disappearance in sera from treated CD patients is complete within 76 ± 34 days after starting the GFD. At this time-point, serum NFR antibodies become observable and persist for a further 75 ± 41 days for a total of 151 ± 37 days from starting the GFD. Our data also show that, after the reintroduction of small amounts of gluten in the diet, NFR antibodies reappear within a few days, much 6-phosphogluconolactonase earlier than serum EMA. The biopsy culture study shows that NFR antibodies are produced early (4–6 h), while EMA appear after more than 12 h from starting the in vitro gliadin challenge. This in vitro finding is consistent with result of the in vivo gluten-induced reactivation of CD. Consequently, given that NFR seems

to be more sensitive than EMA as an early marker of CD reactivation, NFR antibody detection in serum from treated CD patients might become a valuable tool in monitoring adherence to GFD and identifying slight dietary transgressions. The appearance of serum NFR during gluten withdrawal, together with the persistence of symptoms when these antibodies are still positive but EMA are already negative, also suggest that NFR assessment could be an useful tool to determine the right time to perform a second duodenal biopsy. However, before applying these suggestions, our data need to be confirmed by large clinical trials. The presence of a serum NFR-like pattern in some healthy controls evaluated in this study could suggest a low specificity for NFR antibody detection in CD monitoring.