LAMININ AND FIBRONECTIN PROMOTE THE CHEMOTAXIS OF HUMAN-MALIGNANT PLASMA-CELL LINES

We examined chemotaxis of human plasma cells (PCs) in response to extr acellular matrix proteins (ECMs) in the human PC cell lines FR4ds and OPM-1ds. The FR4ds cells expressed beta 1(+), beta 3(-), alpha 2(-), a lpha 3(-), alpha 4(+), alpha 5(+), alpha 6(+), and alpha v(+) integrin s, whereas the OPM-1ds cells expressed beta 1(+), beta 3(-), alpha 2(- ), alpha 3(+), alpha 4(+), alpha 5(-), alpha 6(+), and alpha v(+). Fib ronectin (FN) and laminin (LN) promoted the chemotaxis of the PCs. An inhibitory assay with anti-integrin monoclonal antibodies (MoAbs) show ed that anti-alpha 4 MoAb partially inhibited the chemotaxis of FR4ds and completely inhibited the chemotaxis of OPM-1ds. Anti-alpha 5 MoAb alone had no effect on either of these two lines. Nevertheless, anti-a lpha 5 MoAb completely inhibited chemotaxis when it was added with ant i-alpha 4 in FR4ds, demonstrating a novel complementary role of VLA-5 toward VLA-4 in the chemotaxis induced by FN. LN facilitated chemotaxi s both in OPM-1ds expressing alpha 3 and alpha 6 integrins and in FR4d s expressing alpha 6 integrin alone. Anti-alpha 6 MoAb completely inhi bited FR4ds chemotaxis, whereas anti-alpha 3 and -alpha 6 MoAb had syn ergistic inhibitory effects on the chemotaxis of OPM-1ds. These result s indicated that the distribution of PCs in human tissue are determine d by at least two factors: the concentration of the ECM proteins FN an d LN and the expression of integrins. (C) 1995 by The American Society of Hematology.