Human lymphocyte stimulation by legume lectins from the Diocleae tribe

Lectins from eight leguminous seeds from the Diocleae tribe were compared to Concanavalin A (Con A), a well known T cell mitogen, on the stimulation of lymphocyte proliferation and Interferon gamma (IFN-gamma) production by peripheral blood mononuclear cells (PBMC) from normal volunteers. Lectins from Canavalia brasiliensis and Dioclea virgata induced the highest lymphocyte proliferation, both much higher than levels obtained with Con A, whereas lectins from Dioclea guianensis var. lasiophylla and from Canavalia bonariensis induced the lowest stimulation. Lectins from Dioclea rostrata, D. grandiflora, D. violacea and Cratylia floribunda induced intermediate levels of proliferation. The highest stimulation for IFN-gamma production was obtained with the lectin from D. rostrata, followed by those of C. floribunda and C. brasiliensis; only the lectins from D. virgata and C. bonariensis induced an IFN-gamma production lower than the one obtained by Con A-stimulation. Since all these legumes belong to the same tribe of C. ensiformis (Con A), and all are supposed to exhibit very similar lectins, it is interesting the high variation in the stimulation of lymphocyte proliferation. It is also noteworthy the dissociation between this parameter and IFN-gamma production in the case of D. virgata. A detailed analysis on the structure of such lectins, and their ligand sugars on lymphocyte surface is necessary to further explore such differences.