Calprotectin is used as marker of intestinal inflammation in several gastrointestinal pathologies. In intestinal transplant (ITx) patients several studies have shown that increased levels of calprotectin in intestinal content can result from rejection, infectious enteritis or non specific inflammation [1]. Although it has been proposed as a tool to be added to the clinical follow-up of ITx recipients, the lack of specificity limits its applications. In order to improve our understanding on the factors that contribute to elevated levels of calprotectin, we correlated its values to endoscopic and histologic findings in a cohort of Itx patients under follow-up in our center.

Eleven ITx patients (5 adults, 6 pediatric) were included in the study. Calprotectin levels were determined by ELISA in 137 samples of intestinal content taken during the first two years follow-up. Cases that  presented calprotectin levels above 50 ug/g, were idendified and histological, endoscopical and clinical records were carefully evaluated in order to determine common factors that may be associated to the rise in calprotectin. Among the histologycal parameters evaluated, samples were grouped according to the type and density of the mononuclear/polimorphonuclear celular infíltrate in lamina propria. No correlation with calprotectin levels was detected. On the other hand, all samples (12 among the group analyzed) that presented lack of epitelial barrier continuity, either by histological analysis or by endoscopic analysis (ulcers or scars from previous endoscopies performed in the 48h before the sampling of intestinal content) showed the highest calprotectin levels in intestinal content (p<0.02, T- test).

These results indicate that different factors may contribute to a rise in calprotectin levels, all of them having as common factor the alteration in intestinal epitelial barrier continuity, that may contribute to inflammation driven by direct exposure of lamina propria cell populations to intestinal content.