Receptors for Helix pomatia A Haemagglutinin (HP) on a Subpopulation of Human B Cells

Publisher Website
Google Scholar
Abstract
Receptors for Helix pomatia A haemagglutinin (HP) have earlier been found on neuraminidase treated T-lymphocytes in human peripheral blood. In contrast, the majority of the B-lymphocytes, characterized by surface bound IgM and/or IgD (SIg) lack these receptors. Double marker experiments with fluorochrome labelled reagents have now shown that a minor fraction (3–24%) of the IgM/D bearing lymphocytes in normal human blood also have HP-receptors. These HP+ B-cells constitute approximately 1% of the HP+ lymphocytes in adult blood. Fractionation on HP-Sepharose columns showed that the HP+ B-cells are readily eluted with buffer containing 0.1 mg N-acetyl-D-galactosamine. In contrast, the majority of the HP+-Sig− cells require higher concentrations of the competing hapten for elution (1 mg d-Ga1NAc/ml buffer). This indicates that the HP-receptors on these B-cells differ qualitatively or quantitatively from those on the majority of the T-cells. Previous findings of HP-receptors on the Sig+ leukaemic cells in the blood of patients with chronic lymphocytic leukaemia suggested that these structures are expressed on an immature variety of B-cells. This assumption is favoured by the present finding that approximately 80% of the lymphocytes with surface bound IgM/D in cord blood also have HP-receptors. Therefore, the HP-receptor seems to fall in the category of differentiation markers and constitutes a useful tool for characterization and separation of human lymphocytes within both the T- and the B-compartments.