Partial purification of a mast cell growth-enhancing activity and its separation from IL-3 and IL-4.

A growth factor acting synergistically with IL-3 on thiol-sensitive "mucosal type" bone marrow-derived mast cell lines, and therefore termed mast cell growth enhancing activity, is present in PWM stimulated spleen cell conditioned medium. Mast cell growth enhancing activity can be partially purified and completely separated from IL-3, IL-4, and IL-5, and for the most part from IL-6 and GM-CSF using strong cation exchange and Procion red affinity chromatography. Mast cell growth enhancing activity binds to Con A-Sepharose and can be digested with trypsin and chymotrypsin. It shows a Mr ranging from 37 to 43 kDa under nonreducing SDS-PAGE and a main isoelectric point ranging from 6.2 to 7.3.