Ulex seed extracts: lymphocyte growth inhibition and the anti-H hemagglutinins

Extracts produced from the seeds of Ulex europaeus are commonly used for their ability to react with the H basic substance present on erythrocytes and secreted in body fluids. Such extracts were found to also contain a potent inhibitor of human and murine lymphocyte growth. Inhibition of growth does not result from cytotoxicity and is easily reversible. Ulex seed extract (USE) solutions were modified in various ways to produce reagents in which the anti-H hemagglutinins were either retained or removed. The fractionated solutions were then analyzed for hemagglutination and lymphocyte growth-inhibiting activity. Such studies clearly indicated that these two biological functions resulted from the action of different materials. The lymphocyte growth inhibitor is not a glycoprotein lectin. It does not mediate its effect through the H basic substance and is a heat-stable, small molecule. The data suggest that plant seed extracts employed for their lectin content may contain an additional class of biologically active agents potentially useful in man.