Characterization of ascidian plasma growth factors promoting the proliferation of mouse thymocytes

Abstract

The plasma of a solitaly ascidian, Halocynthia roretzi, stimulates the proliferation of mouse thymocytes in the presence of a mitogen, phytohemagglutinin P (PHA-P). Eight factors capable of stimulating the proliferation of mouse thymocytes were isolated from H. roretzi plasma by procedures including hydrophobic chromatography, gel filtration, and anion-exchange chromatography. Four active fractions with molecular weights of 100-110 K, 75-90 K, 10-30 K, and 5-6 K were first separated by gel filtration. Each of these fractions was then separated into two fractions with different ionic properties by anion-exchange chromatography. The eight factors thus obtained have different heat stabilities, heparin-binding abilities, and PHA-P sensitivities.