A study of immunogold‐labelled blood group A erythrocytes in the scanning electron microscope

Abstract

This report presents binding patterns on A1, A2, A3, Ax and Ae1 erythrocytes of a monoclonal anti‐A (A 003) antibody which reacts predominantly with difucosylated A oligosacccharides, visualized with colloidal gold particles in the backscattered electron imaging mode of a scanning electron microscope. A relatively weak labelling was found on most A, cells, while the labelling in subgroups A2, A3 and especially Ax appeared relatively stronger. Very few Ae1 cells were labelled. The results emphasize the qualitative uniqueness of A1 and suggest that many Ax cells have high proportions of difucosylated A oligosaccharides. Labelling variations were found between different A3 and Ax traits, and in all subgroups between cells and even between different parts of the cells. No immunolabelling differences were found in relation to secretor status.

Binding patterns of monoclonal anti‐B, anti‐H and anti‐(Leb+ Y) on erythrocytes, imaged in the scanning electron microscope

“…We have suggested previously that ABH-related antigens which remain mobile on erythrocytes prefixed with GA, are carried by lipids (7). If so, the proportions of lipid-carried B and H chains may be higher on the convex than on the concave part of the cell, while lipid-carried Y chains may predominate throughout the membrane.…”

“…The reactivity of H 004 is very similar to that of another, recently published moab (code 64/4D8) from the same producer (17). Mouse monoclonal IgM anti-A (code A 003) (7,15) was used for control purposes. All moabs were kindly donated by BioCarb AB, S-223 70 Lund, Sweden.…”

“…Immunolabelling and preparation for electron microscopy: For details, see (7). Erythrocytes were prefixed in 0.06% glutaraldehyde (GA) to prevent agglutination without reducing the antibody binding capacity of the antigens (3,(18)(19)(20), washed in 0.5% glycine and incubated for 30 min with a 1 + 1 dilution of moab.…”

“…The binding of anti-A antibodies to erythrocytes has been studied previously in immunofluorescence (1, 2), transmission electron microscopy (3)(4)(5)(6) and in scanning electron microscopy (SEM) (7). Both polyclonal (1)(2)(3)(4)(5)(6) and mouse monoclonal anti-A (7) have been investigated. These studies have revealed that amount and composition of the antigen A vary between and within the various subgroups of A, between single cells, and between the convex and concave parts of the cells.…”

“…These studies have revealed that amount and composition of the antigen A vary between and within the various subgroups of A, between single cells, and between the convex and concave parts of the cells. Different proportions of A oligosaccharides bound to protein and lipid, respectively, as well as different amounts of mono-and difuco-sylated A oligosaccharides may account for the variations (7).…”