IMMUNOHISTOCHEMICAL DISTRIBUTION AND SERUM LEVELS OF THE CA2-BINDING PROTEINS MRP8, MRP14 AND THEIR HETERODIMERIC FORM MRP8()14 IN CROHNS-DISEASE/

In previous histochemical studies the distribution of the two Ca2+-bin ding proteins MRP8 and MRP14 as well as their heterocomplex MRP8/14 ha s been demonstrated in different inflammatory diseases. Monoclonal ant ibodies against MRP8 and MRP14 and their heterodimer MRP8/14 (27E10 ep itope) were used to investigate immunohistochemically the distribution of these proteins in routinely processed small and large bowel tissue s from patients with Crohn's disease (CD). Furthermore, we used a sand wich immunoassay to measure serum concentrations of MRPs in 62 patient s with CD and in 20 healthy controls. Disease activities of CD patient s were simultaneously assessed by the Crohn's disease activity index ( CDAI) and the severity activity index of Goebell (SAI). In our immunoh istochemical study, MRP8, MRP 14 and the heterocomplex MRP8/14 were de monstrated in the majority of granulocytes and macrophages in active C D. Additionally, a strong complex MRP8/14 immunoreactivity was present in epithelial cells adjacent to ulcerative and fissuring lesions in t he bowel. Serum MRP8/14 concentrations were significantly (p < 0.0001) increased in patients with active CD (CDAI > 150, SAI > 120). No corr elations were found for level of MRP 14 and MRP8 alone, respectively. The follow-up of individual patients with initially active CD showed a further increase in MRP8/14 levels during acute attacks of the inflam matory process. We suggest that our assay for MRP8/14 discriminates we ll between active and inactive CD and may have considerable potential in the analysis of clinical disease activity in CD patients. Our morph ological results confirm the finding of increased MRP8/14 serum levels in patients with active CD.