CLL cells show an impaired adhesion to HUVECs that can be correlated with EFNA4 expression and EphA2-EFNA4 interactions. (A) The percentage of CLL (nos. 1-13) or normal B cells (3 samples), adhered to HUVECs (conjugates) were analyzed by flow cytometry (supplemental Figure 1) after 60 minutes coculture of PKH26-labeled HUVECs with the CFSE-stained B cells. Data are mean ± SD. (B) Percentage of conjugated CLL cells at 60 minutes relative to EFNA4 expression (MFI, Table 1; r, Pearson correlation coefficient, P < .05). (C) HUVECs or B cells (CLL/normal) were preincubated separately with saturating amounts of EFNA4-Fc or EphA2-Fc homodimers, respectively (0.5 μg/106 cells), then washed and cocultured for 60 minutes, as in panel A. The percentage of conjugates in the treated cocultures was expressed as x-fold change relative to control conditions (hFc; x-coordinate crosses y-coordinate at 1). Most treatments were significantly different from hFc controls (P ≤ .05) except that of normal B cells plus EphA2-Fc (nonsignificant).
