Monoclonal Antibody Against the Common β Subunit (βC) of the Human Interleukin-3 (IL-3), IL-5, and Granulocyte-Macrophage Colony-Stimulating Factor Receptors Shows Upregulation of βc by IL-1 and Tumor Necrosis Factor-α

High-affinity receptors for human granulocyte macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), and IL-5 are composed of two distinct subunits, a and 0. Each receptor has its own ligand-specific α subunit, and the three receptors share the common B subunit, βc. Using a transfectant of NIH3T3 cells expressing the high-affinity human GM-CSF receptor, monoclonal antibodies (MoAbs) against βc were generated. These MoAbs specifically bound to cells bearing βc and immunoprecipitated the βc protein of 120 Kd. Using these MoAbs, expression of βc was examined. It is known that IL-1 augments the proliferative response of a human factor-dependent hematopoietic cell line TF-1 to either GM-CSF, IL-3, or IL-5, and that it upregulates the high-affinity receptors for GM-CSF, IL-3, and IL-5. Antibody binding and immunoprecipitation demonstrated that IL-1 increased cell surface expression of βc. This enhancement by IL-1 was accompanied by an increased level of βc mRNA. In addition, we found that tumor necrosis factor-α (TNF-α) also increased the expression of βc, although it did not augment the proliferative response of TF-1 to GM-CSF, IL-3, and IL-5.