Phytohemagglutinins augment red kidney bean (Phaseolus vulgaris L.) induced allergic manifestations.

Red kidney bean (Phaseolus vulgaris L.), a commonly consumed bean has been reported to induce allergic reactions in susceptible individuals. Phytohemagglutinins (PHAs, mainly PHA-P) contribute a major proportion of red kidney bean seeds. However, their roles in red kidney bean induced allergic reactions are still to be explored. This study was carried out to understand the role of PHAs in allergic manifestations using BALB/c mice and cultures of splenocyte, RBL-2H3 cells as well as bone marrow mast cells (BMMCs). Also, the characterization of allergic components from PHA-P was studied by LC-MS/MS. Enhanced levels of specific IgE and IgG1, clinical scores, cytokines and chemokines, β-hexosaminidase, histamine, cysteinyl leukotriene, prostaglandin D2 and abrupt histological changes in the intestine, lung and spleen indicated a pivotal role of PHA-P in red kidney bean allergy. Further, LC-MS/MS study revealed two IgE binding components of PHA-P as PHA-L and PHA-E. Enhanced specific IgE/IgG1 and β-hexosaminidase level elucidated the possible role of PHA-L and PHA-E in allergic manifestations. Furthermore, in the presence of IgE inhibitor piceatannol, reduced β-hexosaminidase release to some extent was noticed. The up regulated expression of GATA-3 and T-bet expression was observed in PHA-L as well as PHA-E groups. Taken together, this study revealed the fact that allergenicity potential of red kidney bean may get augmented due to the presence of different phytohemagglutinins. BIOLOGICAL SIGNIFICANCE: Although food allergy is an immune provocation induced mainly by dietary allergenic protein components of the food, the role of dietary lectins in the food induced allergic manifestations cannot be ruled out. Here we provide the systematic evidences about the allergenic potential of PHAs and further disclosed the culprit components as PHA-L and PHA-E. It is an important finding that the PHA-L and PHA-E can cause allergic manifestations via not only the IgE mediated pathway but also the non-IgE mediated allergic reactions as evident by the Th1/Th2 cytokines and transcription factors. Further, the PHA-L seems to be more allergenic than the PHA-E. This article is part of a Special Issue entitled: Translational plant proteomics.