An sLex-Deficient Variant of HL60 Cells Exhibits High Levels of Adhesion to Vascular Selectins: Further Evidence That HECA-452 and CSLEX1 Monoclonal Antibody Epitopes Are Not Essential for High Avidity Binding to Vascular Selectins

• Published in: The Journal of immunology (1950) 1998-05, Vol.160 (10), p.5122-5129
• Main Authors: Wagers, Amy J, Stoolman, Lloyd M, Craig, Ron, Knibbs, Randall N, Kansas, Geoffrey S
• Format: Article
• Language: English
• Subjects: Animals; Antibodies, Monoclonal - immunology; COS Cells; E-Selectin - metabolism; Epitopes; Glycosyltransferases - metabolism; HL-60 Cells; Humans; Membrane Glycoproteins - analysis; N-Acetylneuraminic Acid - analysis; Oligosaccharides - analysis; P-Selectin - metabolism
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.160.10.5122

Selectins are carbohydrate-binding cell adhesion molecules that play a key role in the initiation of inflammatory responses. Several studies have suggested that the sialylated, fucosylated tetrasaccharide sialyl Lewis X (sLex) is an important component of leukocyte ligands for E- and P-selectin. We have identified a stable variant of the HL60 cell line, HL60var, which displays a nearly complete absence of staining with several mAb directed against sLex and/or sLex-related structures. HL60var also exhibits a concomitant increase in reactivity with mAb directed against the unsialylated Lewis X (Lex/CD15) structure. Despite this sLex deficiency, HL60var binds well to both E- and P-selectin. No significant differences in expression of alpha1,3-fucosyltransferases, C2GnT (Core2 transferase), or P-selectin glycoprotein ligand-1 between HL60var and typical sLex(high) HL60 cells were detected. Although the precise molecular basis for the sLex(-/low) phenotype of HL60var remains uncertain, flow cytometric analysis with the sialic acid-specific Limax flavus lectin revealed a sharp reduction in HL60var surface sialylation. Thus, the loss in mAb reactivity may result from a loss of sialic acid residues from the mAb carbohydrate epitope. However, binding of HL60var to E- and P-selectin remains sensitive to neuraminidase treatment. Taken together, these data indicate that high levels of surface sLex and/or related epitopes are not essential for interactions with vascular selectins, implying that as yet unidentified sialylated, fucosylated structures serve as physiologically relevant ligands for E- and P-selectin.