Partial purification and characterization of a factor from a cloned thymic epithelium cell line

The culture supernatant from a cloned line of thymic epithelium (TEPI) is shown to enhance the response of thymocytes to alloantigen as measured by cell-mediated lympholysis. The supernatant has no effect on the spleen cell response to alloantigen as measured by cell-mediated lysis and does not contain interleukin 1, interleukin 2, interleukin 3, or interferon-γ activity. The activity is shown to have an apparent m.w. of 160,000 by Sephacryl S-200 gel permeation chromatography, to have an isoelectric point of 6.5, and to elute from DEAE-Sepharose at 0.07 M NaCl.