Fibronectin Rescues Bone Marrow Cells from Apoptosis with IgG

Summary

The FDC-P2/185–4 cell line (185–4) is an IL-3 dependent cell line derived from murine bone marrow. 185–4 cell began to die due to apoptosis 12 hours after depletion of IL-3. However, addition of fibronectin with normal IgG rescued the cells from apoptosis by an autocrine mechanism of IL-3. However neither fibronectin alone nor IgG alone induced IL-3. Addition of either RDG peptide or anti-integrin VLA-4 or anti FcγRIII mAb 2.4G2 blocked IL-3 induction, indicating that integrin VLA-5 and FcγRIII are both indispensable cell surface molecules for signal transduction. Other ECM, such as collagen and laminin had no such effect. Thus, fibronectin may play an important role in regulating hematopoietic cells in bone marrow by rescuing them from apoptosis in collaboration with IgG.