The diagnostic value of detection of CD20 positive infiltrates in renal biopsies with acute allograft rejection: a pilot study.

INTRODUCTION: The recognition of antibody mediated rejection has led to re-appreciation of the role of B cells in acute and chronic allograft rejection. The presence of CD20 positive lymphocytic infiltrates in acute cellular rejection has been associated with poor clinical outcomes and reduced graft survival. Recently molecular gene analysis has shown that grafts with antibody-mediated rejection (ABMR) have lower expression of CD20.

METHODS: We reviewed 28 renal allograft biopsies, including 13 biopsies from patients who experienced acute ABMR and a matched group of 15 patients with acute T cell mediated rejection (TCMR) to serve as controls. All biopsies were stained by anti-CD20 and anti-CD8 antibodies.

RESULTS: All twenty-eight biopsies were found to have CD20 positive cells within their interstitial infiltrate. The distribution of CD20 positive cells varied from sparse cells to small or dense clusters in the interstitium. We found no statistically significant differences in CD20 or CD8 cell counts between the ABMR and TCMR groups. We noticed a weak positive correlation between the numbers of CD20 positive cells and the grade/severity of rejection but it didn't reach statistical significance (r=0.37, p=0.06). However, we found a significant positive correlation between the number of CD20 positive cells and intimal artertitis score (r=0.39, p < 0.05).

CONCLUSION: Our findings suggest that there is a possible relation between the presence of CD20 positive lymphocytic infiltrates and a more severe histological form of rejection. However, we failed to establish a relationship between their actual presence in the interstitial infiltrate and distinct mechanisms of graft rejection.