Increase in band 3 density and aggregation in hereditary spherocytosis

Purpose: Red cells in hereditary spherocytosis are characterized by a reduc ed surface area/volume ratio. The mechanisms leading to the loss of membran e material and subsequent elimination of the cells have still not been clar ified. It was the aim of the present study to analyze band 3 distribution i n the red cell membrane and its putative role in red cell elimination. Meth ods/Results: Immunogold histochemistry was performed to detect band 3 in re d cell membranes. Band 3 density and distribution were visualized by electr on microscopy. Unsplenectomized spherocytosis patients (n = 12) showed redu ced band 3 density and aggregation compared to controls (n = 15) (density: 1.2 +/- 0.1 gold particles/mum circumference of red cell membrane vs 1.5 +/ - 0.07 gold particles/mum, x +/- SEM; P < 0.05; aggregation: 0.26 +/- 0.02 aggregates/mum vs 0.3 +/- 0.02 aggregates/mum). By contrast, band 3 density and aggregation were increased in spherocytosis patients who had undergone splenectomy (density: 2.8 +/- 0.1 gold particles/mum vs 2.0 +/- 0.1 gold p articles/mum; P < 0.05; aggregation: 1.5 +/- 0.1 aggregates/mum vs 0.5 +/- 0.03 aggregates/mum; P < 0.01). Artificial ageing of red cells from healthy controls (n = 6) led to a significant increase in band 3 aggregation (2.06 +/- 0.2 aggregates/mum vs 0.33 +/- 0.1 aggregates/mum; P-Wilcoxon < 0.01) but no change in band 3 density. In hereditary spherocytosis (n = 6), both band 3 density and aggregation increased significantly, after artificial ag eing of the red cells. The elevated band 3 aggregation was associated with a stimulated erythrophagocytosis in vitro. Conclusion: Band 3 aggregation c haracterizes the red cells in hereditary spherocytosis. It may be the cause of selective splenic phagocytosis of both spherocytes and senescent erythr ocytes, (C) 2001 Academic Press.