CHARACTERIZATION OF INTERLEUKIN-10 RECEPTORS ON HUMAN AND MOUSE CELLS

Human interleukin (IL)-10 is a pleiotropic cytokine acting on a variet y of immune cells. Here we show that the protein can be enzymatically iodinated to high specific radioactivity with retention of biological activity. The radiolabeled ligand binds specifically to its receptor i n several mouse and human cell lines, notably human B-lymphoma line JY and mouse mast cell line MC/9. Human IL-10 apparently binds as a dime r to a single class of receptor in both the JY and MC/9 cell lines wit h a K(d) in the 50-200 pM range. Interestingly, mouse IL-10 was capabl e of blocking binding of human IL-10 to mouse but not human cells. The re appears to be at most only a few hundred IL-10 receptors/cell for b oth mouse and human cell lines examined. Chemical cross-linking of the radioiodinated hIL-10 to JY and MC/9 cells revealed a common protein complex with an apparent molecular mass of about 97 kDa. Additional hi gh molecular weight complexes were detected with JY but not MC/9 cells .