Functional evidence for a monoclonal antibody that binds to the human IL-4 receptor

The complex pleiotropic effects of the T-cell derived lymphokine interleukin-4 (IL-4) are becoming increasingly well documented; however, functional studies have been hampered by the lack of reagents directed against the receptor for this factor. In this report, we present data which suggest that the monoclonal antibody MR6 binds to the human interleukin-4 receptor (IL-4R). Addition of MR6 to cultures of T cells proliferating in response to IL-4 inhibited this response in a dose-dependent fashion, giving total inhibition at 10 micrograms/ml. Similarly, the IL-4-dependent production of specific antigen-induced IgE by B-cell populations was completely abrogated by MR6. Flow cytometric studies of the modulation of cell surface molecules after T-cell activation suggest that expression of the molecule detected by MR6 (p145-MR6) correlates inversely with that of the interleukin-2 receptor (IL-2R). These data, together with the previously determined molecular weight and tissue distribution of this molecule, strongly indicate that MR6 binds to the human IL-4R.