THE EXTENT OF PERITUBULAR CD14 STAINING - IN RENAL-ALLOGRAFTS AS AN INDEPENDENT IMMUNOHISTOLOGICAL MARKER FOR ACUTE REJECTION

Previously, we demonstrated that in acute interstitial rejection, immu nohistological staining of renal allograft biopsies with the CD14 mAb WT14, reacting with human monocytes/macrophages, shows a characteristi c peritubular increase of positive cells. To test the diagnostic value of this CD14 positivity, we compared, in 154 unselected renal allogra ft biopsies, the extent of peritubular WT14 staining with (a) the orig inal histological diagnosis, made with knowledge of clinical data, (b) the retrospectively and blindly scored histological diagnosis accordi ng to the criteria of the Banff classification, and (c) the eventual c linical diagnosis, which included evaluation of the response to therap y. The extent of peritubular WT14 positivity, blindly scored on cryost at sections of the frozen part of the biopsies, correlated positively with the probability of acute rejection (AR). When using a cutoff of 7 0% WT14 positivity for the diagnosis of AR, as extracted from a receiv er operating characteristic curve, the WT14 diagnosis had a positive p redictive value of 91% and a negative predictive value of 56%, compare d with the original histological diagnosis. Compared with the Banff di agnosis of AR (grade I-III), these values were 95% and 47%, and compar ed with the clinical diagnosis, 84% and 63%, respectively. The WT14 di agnosis essentially corrected the original histological diagnosis in 7 cases, and was consistent with the eventual diagnosis in 5 equivocal cases. We conclude that the extent of peritubular CD14 positivity can be used as a marker for AR and can serve as a valuable additional crit erion for AR in the histological examination of renal allograft biopsi es.