Mitogenic stimulation of human lymphocyte subpopulations by Lathyrus odoratus lectin

Investigation was made of the mitogenic activation by Lathyrus odoratus (LATH) lectin and phytohaemagglutinin (PHA) of human T-enriched and non-T lympohcytes isolated by nylon wool filtration and sheep erythrocyte rosette depletion, respectively. LATH stimulated only weakly the T-enriched and non-T fractions as compared to PHA which strongly stimulated the T-enriched population and weakly stimulated the non-T cells. Removal of phagocytic cells from the unfractionated lymphocytes caused only a slight reduction in the response to LATH. The responses of mixtures of T-enriched and non-T lymphocytes were similar to that of unfractionated lymphocytes. The LATH lectin seems, therefore, to be neither a pure T nor a pure non-T cell mitogen, since both populations must be present for optimal response. When alpha-methyl-D-mannoside was added to unfractionated lymphocytes together with LATH, there was a strong inhibition of thymidine incorporation. D-glucose and N-acetyl-D-glucosamine diminished the stimulation effect to a lesser degree.