Expression of Adhesion Molecules on Myeloma Cells

We investigated the expression of adhesion molecules including LFA‐1α (CD11a), Mac‐1 (CD11b), LFA‐1β (CD18), VLA‐β(1), (CD29), H‐CAM (CD44), VLA‐4 (CD49d), VLA‐5 (CD49e), ICAM‐1 (CD54), N‐CAM (CD56), LFA‐3 (CD58), VNR‐β (CD61), and LECAM‐1 (CD62L) on fresh myeloma cells and human myeloma cell lines. By two‐color flow cytometric analysis with anti‐CD38 antibody, we demonstrated that myeloma cells were located in the strongly CD38‐positive (CD38(++)) fractions. Fresh myeloma cells were obtained from 28 patients with multiple myeloma (MM) and 3 patients with plasma cell leukemia (PCL). All myeloma cells expressed VLA‐4 on their surface. Most of the myeloma cells also expressed VLA‐5, ICAM‐1, and LFA‐3. H‐CAM was strongly expressed in 3 cases of PCL and 2 cases of aggressive myeloma, and moderately expressed in other MMs. N‐CAM was expressed in 68% of MMs, but none of the 3 PCLs. LFA‐1 was expressed in two cases of aggressive myeloma, but not expressed in other non‐aggressive myelomas. Most of the myeloma cells did not express Mac‐1, VNR‐β, or LECAM‐1. These results suggest that VLA‐4, VLA‐5, ICAM‐1, LFA‐3, and H‐CAM are involved in cellular interaction and migration in MM, and that the expression of N‐CAM and LFA‐1 varies with disease activity in MM.