Monoclonal antibodies against the human interleukin-11 receptor alpha-chain (IL-11Rα) and their use in studies of human mononuclear cells

A panel of 14 hybridoma cell lines secreting monoclonal antibodies against the human interleukin-11 receptor alpha chain (hIL-11R alpha) was obtained using two different approaches. Two antibodies were raised against peptides of the N- and C-terminal sequences, respectively, of the extracellular part of the hIL-11R alpha. Another group of 12 antibodies was generated against a hybrid protein consisting of the extracellular part of the hIL-11R alpha fused to mature full-length human IL-2. All these antibodies recognized native hIL-11R alpha and most also recognized the denatured receptor on immunoblots after SDS-PAGE. Four different epitopes were identified on the extracellular part of the hIL-11R alpha. One epitope, defined by the E27 antibody, is located at the N-terminus and the other three epitopes are clustered in the membrane-proximal, C-terminal region. The antibodies defining epitopes I and II recognized membrane-bound hIL-11R alpha expressed in gp130/hIL-11R alpha-cotransfected Ba/F3 cells. The E27 antibody cross-reacted with murine IL-11R alpha, in agreement with the fact that the N-terminal region is highly conserved between species. The other 13 antibodies all recognized a region between amino acids 319 and 363, which is the membrane-proximal part of the hIL-11R alpha. This region, which is less conserved between mouse and human, is shown here to be an immunodominant region. Anti-IL-11R alpha monoclonal antibodies, which have not been described previously enabled us to explore the expression and tissue distribution of IL-11R alpha on human peripheral blood mononuclear cells and cell lines. The antibodies provide powerful tools for the study of the regulation and function of the receptor. (C) 2000 Elsevier Science B.V. All rights reserved.