Miltenberger blood group antigen subtype III (Mi.III) supports Wr(b) expression.

Background and Objectives Miltenberger blood group antigens belong to the complex MNS system. Miltenberger antigen subtype III (Mi.III) was previously found to promote the expression of band 3. Here, we investigated whether the direct interaction between band 3 and Mi.III-specific Gp.Mur (a glycophorin B-A-B hybrid) might affect the expression of related blood group antigens such as the Wright b (Wrb) antigen. Materials and Methods (1) Band 3 genes of Mi.III+ and non-Mi.III (control) donors were sequenced to determine the genotypes of the Wright antigens. (2) The expression levels of Wrb, glycophorin A (GPA) and band 3 in Mi.III and the control erythrocytes were quantitatively assessed by flow cytometry. Results Mi.III erythrocytes expressed 22 center dot 5 +/- 6 center dot 6% more Wrb antigen than the control cells. The increase in Wrb in Mi.III cells was independent of their GPA levels. Conclusion The elevated Wrb levels in Mi.III RBCs were likely linked to their higher band 3 levels. Higher band 3 densities on the Mi.III+ cell surface conceivably could drive complex formation between band 3 and GPA/Gp.Mur, thereby increasing the expression of Wrb.