EFNA4 signaling of CLL cells down-modulates CD44 expression and decreases their adhesion to ECM molecules and ICAM-1 or VCAM-1 CAMs. (A) CLL cells were cultured for 1 hour in the absence (empty profiles) or presence (gray histograms) of saturating amounts (0.5 μg/106 cells) of soluble EphA2-Fc homodimers, then stained with Abs for flow cytometric analyses of CD18, CD29, CD62-L (top), CD11a, CD49d, or CD44 expressions (bottom; black histograms, background staining). A representative experiment is shown. (B) EphA2-Fc–incubated (0.5 μg/106 cells) or hFc-only–treated CLL cells (CLL nos. 1, 3, 4, 5, 8, 10, and 13), corresponding to different EFNA4 expression levels (Table 1), or normal B cells (3 samples), were cultured for 2 hours onto ECM- or CAM-coated culture wells (3 × 105/well). Nonadhered cells were recovered and counted by the use of FACS. A measure of the effect of EphA2-Fc treatment on the cells adhesion was expressed as x-fold change relative to control hFc (number of nonadhered cells recovered in the treated cultures divided by those recovered in the corresponding hFc control ones) and represented against the corresponding EFNA4 expression (MFI) as determined by FACS (r, Pearson correlation coefficient, P < .05). Values are mean from triplicates.
