Expression of wild-type and ITIM-less PECAM-1 on the surface of B-cell transfectants.

DT40 B cells were transfected with (A) wild-type human PECAM-1 or (B) an ITIM-less human PECAM-1 variant, in which the tyrosine residues at positions 663 and 686 were replaced by phenylalanine. Cells were pretreated with normal mouse IgG1 (NMIgG) or with PECAM-1.3, a murine mAb specific for human PECAM-1 (αPECAM-1). Antibody-pretreated cells were then stained with FITC-conjugated GAM IgG and analyzed by flow cytometry. Transfectants chosen for analysis expressed equivalent levels of cell surface PECAM-1.