Novel polypeptides, polynucleotides encoding the polypeptides, and related compositions and methods are disclosed for zcytor19, a novel class II cytokine receptor. The polypeptides may be used within methods for detecting ligands that stimulate the proliferation and/or development of hematopoietic, lymphoid and myeloid cells in vitro and in vivo. Ligand-binding receptor polypeptides can also be used to block ligand activity in vitro and in vivo. The polynucleotides encoding zcytor19, are located on chromosome 1p36.11, and can be used to identify a region of the genome associated with human disease states. The present invention also includes methods for producing the protein, uses therefor and antibodies thereto.