Interleukin 3 (IL 3) was initially defined as a factor in conditioned media from concanavalin A-stimulated lymphocytes (Con A CM) that induces the enzyme 20-α-hydroxysteroid dehydrogenase (20αSDH) in cultures of nu/nu splenic lymphocytes. To determine the spectrum of additional 'biologic' activities, IL 3 was purified to homogeneity and its properties were assessed. The protein preparation was judged to be homogeneous IL 3 by the following criteria: 1) elution of a peak of IL 3 with a constant specific activity in the last step of purification, 2) presence of a single protein by SDS-PAGE analysis, 3) receptor-binding activity against IL 3-dependent cell lines, 4) a specific activity of ≃0.2 ng/ml required for 50% of maximal biologic activity, and 5) the presence of a single amino terminal sequence. With the use of this preparation of IL 3, the dose-response curves for 20αSDH induction were identical or similar to the dose-response curves of the activities of 1) WEHI-3 growth factor, 2) mast cell growth factor, 3) P cell-stimulating factor, and 4) histamine-producing cell-stimulating factor. In addition, homogeneous IL 3 had colony-stimulating factor activity although only approximately 2% of the total CSF activity found in Con A CM was associated with IL 3. The major peak of CSF activity could be resolved from IL 3 by DEAE column chromatography and lacked many of the biologic activities associated with IL 3.
|Original language||English (US)|
|Number of pages||6|
|Journal||Journal of Immunology|
|State||Published - 1983|
ASJC Scopus subject areas
- Immunology and Allergy