Blood Group A and B Antigen Expression in Human Kidneys Correlated to A1/A2/B, Lewis, and Secretor Status

BACKGROUND: In the revived interest in crossing ABO barriers in organ transplantation renal A/B antigen expression has been correlated with donor ABO, Lewis, and secretor subtype to predict antigen expression. METHODS: A/B antigen expression was explored by immunohistochemistry in LD renal biopsies. Donor A1/A2/B, Lewis, and secretor status were determined by serology and polymerase chain reaction. RESULTS: In the renal vascular bed, three distinct A antigen expression patterns with a major, minor, and minimal staining distribution, and intensity (designated as types 3+, 1+ and (+) respectively) were identified. Type 3+ had a strong A antigen expression in the endothelium of arteries, glomerular/peritubular capillaries and veins. The type 1+ showed an overall weaker antigen expression, whereas type (+) had faint staining of peritubular capillaries only. In all cases, distal tubular epithelium was focally stained, whereas proximal tubules were negative. Type 3+ were all from blood group A1 subtype individuals while A2 cases expressed either a 1+ or (+) pattern. The secretor gene did not appear to influence renal A antigen expression. All B kidneys examined showed a B antigen pattern slightly weaker but otherwise similar to A type 3+. CONCLUSION: Renal vascular A antigen expression correlates to donor A1/A2 subtypes, whereas B individuals show one singular antigen pattern. From antigen perspective, A1 and B donors are a "major" and A2 individuals a "minor" antigen challenge in ABO-incompatible renal transplantation.