Binding of mitogenic plant lectins to human lymphocytes. Flow cytometric analysis.

Several plant lectins, such as phytohaemagglutinin (PHA), pokeweed mitogen (PWM), concanavalin A (ConA), Maclura pumifera (MPA) and Pisum sativum agglutinin (PSA), are potent mitogens for human lymphocytes. The pattern of activation induced, however, is not uniform for all mitogenic lectins. The different biological effects following lectin activation of human lymphocytes might be due at least in part to a differential binding of the various lectins to lymphocyte subsets. We have therefore studied the binding of five mitogenic plant lectins, namely PHA, PWM, ConA, MPA and PSA to three major human lymphocyte subsets as defined by anti-CD4, anti-CD8 and anti-CD16 monoclonal antibodies. Dual colour, flow cytometric analysis employing PE-conjugated monoclonal antibodies and FITC-conjugated lectins revealed that all subsets uniformly show high binding of PHA, whereas two different populations, one high binding and the other low binding, can be detected with PWM, ConA, MPA and PSA.