Innovations in measuring and mitigating phytohemagglutinins,a key food safety concern in beans

Phytohemagglutinin(PHA)is a seed storage protein and a type of lectin originally discovered in the common bean(Phaseolus vulgaris)for its blood-agglutinating effect.Due to its interactions with gut epithelia and digestive enzymes and its potential to trigger allergic reactions,PHA can lead to various symptoms in the human body.As a result,it has been regarded as a signifcant antinutritional factor in beans and other legumes.While several published works have summarized its structural,biochemical,and toxicological features,there is a scarcity of literature that reviews the detection,quantifcation,and reduction of PHA in beans,which is fundamental for the development of safer bean varieties.In this review,we present a comprehensive analysis of traditional and innovative bio-sensing methods for measuring PHA,including the recently available ultrapure liquid chromatography–tandem mass spectrometry and emerging aptamer sensor-based techniques,while discussing their respective advantages and disadvantages.We also revisit existing studies dedicated to creating PHA-depleted common bean varieties and explore the potential for reducing PHA content in beans without compromising their resistance to biotic stress.Additionally,we offer insights into the potential for controlling PHA content using the latest biotechnologies and breeding strategies.Overall,this review compiles rare and valuable information from studies that solely focuses on detection and depletion of PHA to shed light on and apply technological advancements in addressing potential food safety risks associated with the consumption of common beans.

DNA Damage Response in Resting and Proliferating Peripheral Blood Lymphocytes Treated by Camptothecin or X-ray

DNA damage response （DDR） in different cell cycle status of human peripheral blood lymphocytes （PBLs） and the role of H2AX in DDR were investigated. The PBLs were stimulated into cell cycle with phytohemagglutinin （PHA）. The apoptotic ratio and the phosphorylation H2AX （S139） were flow cytometrically measured in resting and proliferating PBLs after treatment with camptothecin （CPT） or X-ray. The expressions of γH2AX, Bcl-2, caspase-3 and caspase-9 were detected by Western blotting. DDR in 293T cells was detected after H2AX was silenced by RNAi method. Our results showed that DNA double strand breaks （DSBs） were both induced in quiescent and proliferating PBLs after CPT or X-ray treatment. The phosphorylation of H2AX and apoptosis were more sensitive in proliferating PBLs compared with quiescent lymphocytes （P0.05）. The expression levels of anti-apoptotic proteins Bcl-2 were reduced and cleaved caspase-3 and caspase-9 were increased. No significant changes were observed in CPT-induced apoptosis in 293T cells between H2AX knocking down group and controls. It was concluded that proliferating PBLs were more vulnerable to DNA damage compared to non-stimulated lymphocytes and had higher apoptosis rates. γH2AX may only serve as a marker of DNA damage but exert no effect on apoptosis regulation.

Correlations between phytohemagglutinin response and leukocyte profile,and bactericidal capacity in a wild rodent

phytohemagglutinin(PHA)-induced swelling is widely used to investigate cell-mediated and innate immunity across different vertebrate taxa.However,its physiological mechanism is still an open question due to the complexity of the involved immune components.In the present study,we measured the synchronous variations of PHA response,the proportion of different subtypes of leukocytes,as well as serum bactericidal capacity in circulation blood at 6,12 and 24 h after PHA versus PBS injection in striped hamster,Cricetulus barabensis.First,the results showed that PHA responses reached a peak at 6 h postinjection,then sharply declined at 12 h and 24 h postinjection.Serum bactericidal capacity was higher at 6 h and 12 h than at 24 h.The proportion of different subtypes of leukocytes,as well as the ratio of neutrophils to lymphocytes did not display significant changes across different time points.Second,PHA response was positively correlated with the proportion of neutrophils and serum bactericidal capacity.The proportion of monocytes was negatively correlated with that of eosinophils and neutrophils.The proportion of basophils was negatively correlated with that of lymphocytes.Our results indicate that earlier enhanced PHA response is important for the striped hamster to cope with changing environmental conditions due to its small body mass,and the increased components of innate immunity in circulation blood may contribute to the enhancement of PHA swelling response.

The Effect of Anti-Human CD134 Monoclonal Antibody on Phytohemagglutinin-Induced mRNA Expression of Perforin in Peripheral Blood Mononuclear Cells

CD134, a member of the tumor necrosis factor receptor superfamily, plays a crucial role in T cell survival. In this study, peripheral blood mononuclear cells （PBMCs） stimulated with phytohemagglutinin （PHA, 50 μg/ml） were treated by CD134 mAb （1μg/ml, 5 μg/ml, 10 μg/ml） for 6 h, 12 h, 24 h and 48 h. The level of perforin mRNA was measured by reverse transcription-polymerase chain reaction （RT-PCR） technique. Our data showed that the expression of perforin mRNA in PBMCs was down-regulated by CD134 mAb in a dose-dependent manner in range of 1 μg/ml to 5 μg/ml and dropped down to its minimum on 24 h （p 〈 0.05）. The level of perforin mRNA reached a plateau when the concentration of CD134 mAb exceeded 5 μg/ml. In conclusion, CD134 mAb can inhibit perforin expression, which may enhance the ability of T cells for survival. Cellular ＆ Molecular Immunology. 2005;2（6）： 467-471.