Properties and separation of T lymphocyte growth stimulatory activity (TL‐GSA) and of granulocyte‐macrophage colony stimulatory activity (GM‐CSA) produced separately from two human T lymphocyte subpopulations

Abstract

We have previously identified two stimulatory activities affecting blood cell maturation in PHA-stimulated human lymphocytes conditioned medium (PHA-LyCM). One was granulocyte-macrophage colony stimulatory activity (GM-CSA), and the other was T lymphocyte growth stimulatory activity (TL-GSA) in suspension culture. In this paper we have shown that although both activities can be produced from purified non-adherent human T lymphocytes, they are produced from two distinct subpopulations. The production of these activities was greatly enhanced by T cell mitogens. Both protein factors were relatively heat stable (56 degrees, 30 minutes), were sensitive to trypsin treatment and were specific for primate blood cells. These two activities were fractionated by means of ammonium sulfate precipitation, Sephadex G-150 gel filtration, DEAE cellulose and Con A-Sepharose column chromatographies. MW of the major peak estimated from the elution volume of gel filtration in the presence of 0.5 M NaCl was 40,000 for GM-CSA and 13,000 for TL-GSA. Results from Con A-Sepharose column showed that while about 70% of TL-GSA was bound to Con A, less than 25% of GM-CSA was bound. These observations show that the majority of TL-GSA and GM-CSA were separable by these two conventional column chromatographic methods.