P0127ROUTINE USE OF COMBINATION CD3/PAS STAIN IN EVALUATING RENAL ALLOGRAFT BIOPSIES FOR REJECTION RESULTS IN MORE ACCURATE BANFF SCORES FOR TUBULITIS

Abstract

Abstract Background and Aims The BANFF Classification of renal allograft rejection consists of scores for cellular rejection which rely primarily on the evaluation of lymphocytic infiltration into tubules (t), non-atrophic interstitial inflammation (i), total inflammation (ti), and endotheliatis (v.) CD3/PAS is a combination stain that highlights T lymphocytes (CD3) and basement membrane (PAS). The original BANFF scoring was developed using a hematoxylin and eosin (H&E) stain only. This study compares scores for (t) using H&E versus CD3/PAS. Method 50 consecutive renal allograft biopsies were retrieved and on each case H&E and CD3/PAS combination stains (Ventana/Roche tissue Diagnostics Clone 2GV6 for CD3) were performed. One blinded group of matching CD3/PAS and H&E slides were evaluated and reviewed independently by two renal pathologists (Reviewer 1 and 2). Each case was graded in an identical manner following criteria designated for (t) as previously described in the Banff Classification for Renal Allograft Biopsies. Briefly (t)=0 no lymphocytes in 10 tubule cross section (tcx), (t)=1 between 1-4 lymphocytes per tcx, (t)=2 5-10 lymphocytes per tcx and (t)=3 greater than 10 lymphocytes per tcx. Cases were not graded for (v) as there were too few cases with endotheliatis to allow for statistical evaluation. The difference between CD3/PAS versus H&E scores were tested for significance using the Wilcoxon Signed Rank test. All p values were two-tailed and values of <0.05 were considered statistically significant. Results Mean age was 44 years with a range of 9 -75 years. Standard deviation (SD) for age was 18 years. Gender distribution was 20% female and 80% male. 28 cases were graded as (t) = 0 in H&E versus 18 in the CD3/PAS group (59% versus 36%). 17 cases were graded as (t)=1 in H&E group versus 19 in the CD3/PAS group (36% versus 38% respectively). 2 cases were graded (t)=>2 in H&E versus 12 cases in CD3/PAS groups (4% versus 24% respectively). In all categories of (t) there was a higher (t) score when using a CD3/PAS with 42% showing a one digit score increase and 8% showing a 2 digit increase. The difference in scoring for (t) between the H&E set versus the CD3/PAS set for both Reviewers 1 and 2 were statistically significant (p<0.0001). Conclusion This study showed statistically significant higher tubulitis scores when using a CD3/PAS combination stain to grade allograft biopsies. Since (t) scores directly affect the diagnosis of cellular rejection, we propose routine use of CD3/PAS in addition to H&E when reviewing renal allograft biopsies. Compared with H&E, CD3/PAS makes recognition and quantification of lymphocytes crossing the tubular basement membrane easier to detect and therefore more accurate.