Specific binding, internalization, and degradation of human recombinant interleukin-3 by cells of the acute myelogenous, leukemia line, KG-1
✍ Scribed by Thomas G. Gesner; R. Allan Mufson; Christine R. Norton; Katherine J. Turner; Yu Chung Yang; Steven C. Clark
- Publisher
- John Wiley and Sons
- Year
- 1988
- Tongue
- English
- Weight
- 745 KB
- Volume
- 136
- Category
- Article
- ISSN
- 0021-9541
No coin nor oath required. For personal study only.
✦ Synopsis
We have studied the interaction of 35S-labeled recombinant IL-3 with the acute myelogenous leukemia cell line, KG-1. 35S-IL-3 bound to these cells in a time dependent, saturable, and specific manner at 4OC. Scatchard transformation of binding isotherms demonstrated the existence of a small number (200) of binding sites, with an apparent dissociation constant of 70-105 pM. After a temperature shift from 4OC to 37OC, surface-bound 35S-IL-3 was rapidly internalized and processed into a trichloroacetic acid soluble form that was released into the medium. Experiments to address the specificity of the IL-3 binding site revealed that neither human IL-2, M-CSF, erythropoietin, transferrin, bovine insulin, nor murine nerve growth factor compete with IL-3 for binding to KG-1 cells. Both human and gibbon recombinant IL-3 and, surprisingly, human recombinant GM-CSF effectively competed the binding of the labeled IL-3 to these cells at 4OC. The competition by GM-CSF was found to be concentration dependent, but much higher concentrations were required to achieve t h e levels obtained with IL-3. These results suggest that GM-CSF may also interact with the high-affinity IL-3 binding site on KG-1 cells or, alternatively, that GM-CSF binding to its own receptor may decrease the affinity of the IL-3 receptor for its ligand.
Interleukin 3 (IL-31, also known as multilineage col-been identified on normal bone-marrow-derived progenony-stimulating factor (multi-CSF) is a member of a itor cells as well as on mature neutrophils, eosinophils, family of hematopoietic growth factors that supports the and monocytes (Nicola and Metcalf, 1986). As has been survival, proliferation and development of hemato-observed with the receptors for GM-CSF (Gasson et al., poietic progenitor cells (reviewed in Metcalf, 1986; Clark 19861, granulocyte-CSF (G-CSF) (Nicola and Metcalf, and Kamen, 1987). Within this family there is an appar-19851, and erythropoietin, the absolute numbers of reent hierarchy of action of the individual factors with ceptors on normal cells are relatively low, usually 100progenitor cells as they progress through the develop-1,000 per cell. Although each of these CSFs has been mental programs characteristic of the different cell lin-shown to interact with different receptors on normal eages. Thus, in both the murine and human systems, murine cells, a hierarchy of receptor down modulation