A fast-acting cytotoxin derived from Con A-activated porcine leukocytes: I. Biochemical characteristics and target cell specificity

We here describe a new cytotoxin which was detected in serum-free culture supernatants of mitogen stimulated porcine leukocytes. The factor was precipitated at 35–45% (NH 4) 2 SO 4 concentration, sensitive to heat, low pH, and trypsin, thus indicating its protein nature. Column chromatography on hydrophilic or hydrophobic matrices revealed ampiphilic properties. The smallest unit which was sufficient to induce complete target cell lysis had a molecular weight of 33K. This porcine cytotoxin (PCT) could be distinguished functionally from lymphotoxin (LT) and tumor necrosis factor (TNF). It is a fast acting mediator which exerts strong cytostatic and cytotoxic anti-tumor activity using a panel of T lymphoma target cells.