Production of monoclonal antibody against granulomonopoietic enhancing activity (GM-EA)

The granulomonopoietic enhancing activity (GM-EA) is a novel myelopoietic synergizing factor which acts as an enhancing factor for the proliferation and/or maturation of myelopoietic progenitor cells (CFU-GM) in combination with various types of colony-stimulating factors. In the present study, we report the production of a mouse anti-human GM-EA monoclonal antibody (mAb) designated 63A which is of the IgG1 subclass and has kappa light chains. This mAb can be used to quantitate GM-EA using a solid-phase enzyme-linked immunoabsorbent assay (ELISA) and is shown to have no cross-reaction with other myeloid synergizing factors. Furthermore, 63A mAb can significantly neutralize the colony-enhancing activity of GM-EA when added to CFU-GM assay cultures. In addition to being a convenient tool for the assay of GM-EA, 63A mAb may also be valuable for the exploration of the full potential of this enhancing factor in myelopoiesis.