The present invention relates to compositions of matter and methods for the treatment and diagnosis of immune related diseases, including those mediated by cytokines released primarily either Th1 or Th2 cells in response to antigenic stimulation. The present invention further relates to methods for biasing the differentiation of T-cells in either the Th1 subtype or the Th2 subtype based on the relative expression levels of the gene PRO92726, and its agonists or antagonists. The present invention further relates to a method of diagnosing Th1- and Th2-mediated diseases.