Selectin binding activity of sialyl 6-sulfo Le^x expressed on helper memory T cells. Inhibition of the binding of recombinant E-selectin (A), P-selectin (B), or L-selectin (C) immunoglobulin to CD45RO⁺ cells by anti–sialyl 6-sulfo Le^x (G152) or anti-CLA (HECA-452) antibody. Specific binding of recombinant selectin immunoglobulin was ascertained by the inhibition with EDTA. KPL1 is an anti–PSGL-1 antibody. Results of 4-color analyses using anti-CD3, anti-CD4, and anti-CD45RO antibodies and recombinant selectin immunoglobulin in the presence or absence of inhibitory antibodies. Two-dimensional distribution of recombinant selectin immunoglobulin staining with CD45RO on gated CD3⁺CD4⁺ T-cell population was plotted.