Expression of β 1 Integrins (Very Late Antigens-4 and −5) on Myeloma Cells and Clinical Correlates in Patients with Multiple Myeloma

Abstract

β₁ Integrins are considered to be essential for the differentiation of bone-marrow B cells through an interaction with fibronectin-expressed bone-marrow stromal cells. The expression of very late antigens-4 (VLA-4) and −5 (VLA-5) by CD38^bright bone-marrow cells in patients with multiple myeloma was measured by flow cytometry using specific monoclonal antibodies. The percentage of CD38^bright bone-marrow cells appeared to correlate with that of bone-marrow plasma cells as judged by examination of bone-marrow smears (r = 0.911, P < 0.0001). Expression of VLA-4 and VLA-5 by CD38^bright cells varied between patients, but the expression of VLA-4 was always equal to or greater than that of VLA-5. The ratio of VLA-4 to VLA-5 expression (VLA-4:VLA-5 ratio) was calculated and compared with the clinical features of the myeloma patients. A high VLA-4: VLA-5 ratio (> 2.0) was associated with the presence of plasmacytomas and urinary Bence-Jones protein was more common in this group. No other correlations between the clinical features of the disease and the expression of β₁ integrins were found.