Studies on a phytohemagglutinin from the common lentil: VI. Stimulation of human peripheral lymphocytes in culture by Lens culinaris hemagglutinin A

Abstract

Human blood lymphocytes are stimulated in culture by the homogeneous lentil hemagglutinin LcH-A. 1 1 Abbreviations: Lens culinaris hemagglutinin A, LcH-A; Phaseolus vulgaris hemagglutinin, PHA. In order to stimulate lymphocytes LcH-A must be bound to the surface for 24 h after which blastogenesis occurs in the absence of LcH-A. Blastogenesis is prevented by either sugars which bind to LcH-A or specific rabbit anti-LcH. In the presence of LcH-A, there is an almost immediate increase in uptake by the lymphocytes of uridine and incorporation into TCA-precipitable material. At the same time there is a small increased uptake of leucine and incorporation into TCA-precipitable material. After a lag of 24 h, thymidine is rapidly taken up by the cells and also incorporated into TCA-precipitable material. Finally, a large increased uptake of leucine occurs during a period where the total cell number is increasing. A critical blastogenic committal time of about 24 h was observed which was characterized by thymidine uptake, and a change in cell surface properties. It is suggested that, because a similar sequence of events occurs with PHA (a phytohemagglutinin with a different specificity than LcH-A) and Con A, the three lymphocyte stimulants bind similar or identical receptor sites, and/or stimulate by a similar mechanism.