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 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.