Lectin Research Abstracts
Lectins in the United States diet: a survey of lectins in commonly consumed foods and a review of the literature.
Nachbar MS, Oppenheim JD
Am J Clin Nutr 1980 Nov;33(11):2338-2345
Plant lectins or phytohemagglutinins possess potent in vivo biological activities. Some, primarily of the family Leguminosae, have been shown to have deleterious nutritional effects. Little information exists, however, regarding the prevalence of lectins or the specific foods that contain lectins in the United States diet. In the present study the edible parts of 29 of 88 foods tested, including common salad ingredients, fresh fruits, roasted nuts, and processed cereals were found to possess significant lectin-like activity as assessed by hemagglutination and bacterial agglutination assays. Based on this survey and a review of the literature we conclude that dietary exposure to plant lectins is widespread. The spectrum of nutritional consequences of such exposure remains to be determined.
Dietary lectins can induce in vitro release of IL-4 and IL-13 from human
Eur J Immunol 1999 Mar;29(3):918-27
Haas H, Falcone FH, Schramm G, Haisch K, Gibbs BF, Klaucke J, Poppelmann M, Becker WM, Gabius HJ, Schlaak M.
Forschungszentrum Borstel, Germany. firstname.lastname@example.org
Dietary lectins, present in beans and other edible plant products, pose a potential threat to consumers due to their capacity to induce histamine release from basophils. In this study, we analyzed the capacity of 16 common, in particular dietary, lectins to induce human basophils to secrete IL-4 and IL-13, the key promoters of Th2 responses and IgE synthesis. Several of the lectins, especially concanavalin A, lentil lectin, phytohemagglutinin, Pisum sativum agglutinin and Sambucus nigra agglutinin, triggered basophils to release IL-4 at concentrations of up to 1 ng/10(6) basophils. Lectins with high IL-4-inducing capacity also stimulated the release of IL-13 and histamine. Lectin-induced IL-4 and IL-13 release reached a maximum after 4-6 h and more than 18 h, respectively. Affinoblotting revealed that lectins with the capacity to induce mediator release bind to IgE, suggesting IgE binding as initial step of signal generation. In conclusion, several dietary lectins can trigger human basophils to release IL-4 and IL-13. Since lectins can enter the circulation after oral uptake, they might play a role in inducing the so-called early IL-4 required to switch the immune response towards a Th2 response and type I allergy.
Modulation of immune function by dietary lectins in rheumatoid arthritis.
Br J Nutr 2000 Mar;83(3):207-17
Cordain L, Toohey L, Smith MJ, Hickey MS.
Department of Health and Exercise Science, Colorado State University, Fort Collins 80523, USA. email@example.com
Despite the almost universal clinical observation that inflammation of the gut is frequently associated with inflammation of the joints and vice versa, the nature of this relationship remains elusive. In the present review, we provide evidence for how the interaction of dietary lectins with enterocytes and lymphocytes may facilitate the translocation of both dietary and gut-derived pathogenic antigens to peripheral tissues, which in turn causes persistent peripheral antigenic stimulation. In genetically susceptible individuals, this antigenic stimulation may ultimately result in the expression of overt rheumatoid arthritis (RA) via molecular mimicry, a process whereby foreign peptides, similar in structure to endogenous peptides, may cause antibodies or T-lymphocytes to cross-react with both foreign and endogenous peptides and thereby break immunological tolerance. By eliminating dietary elements, particularly lectins, which adversely influence both enterocyte and lymphocyte structure and function, it is proposed that the peripheral antigenic stimulus (both pathogenic and dietary) will be reduced and thereby result in a diminution of disease symptoms in certain patients with RA.
Lectins and the intestine.
J Pediatr Gastroenterol Nutr 1983 Nov;2(4):588-94
Lectins are being used increasingly for the study of carbohydrate structures in the small and large intestine. These substances are particularly useful for characterization of normal and abnormal intestinal mucus, but they are also important probes for investigation of epithelial surface changes associated with differentiation and maturation. Lectins are contained in significant amounts in a great variety of products ingested in the human diet. This, and the demonstration of their harmful effects on intestinal epithelium in rodents, indicate a need for investigation of potential adverse actions of lectins on human intestine.
Immunological aspects of the potential role of dietary carbohydrates and lectins in human health.
Eur J Nutr 1999 Jun;38(3):107-17
Department of Transfusion Medicine, South-East Scotland Blood Transfusion Centre, Edinburgh, Great Britain.
BACKGROUND: Little is known regarding the immunobiology of dietary carbohydrate intake and its relevance to human health, although foodstuffs contain many simple and complex carbohydrates. SYNOPSIS: Lectins, immunoglobulins, viruses, bacteria and host cells interact with each other forming a delicate equilibrium within the alimentary canal which may be perturbed by saccharide intake. The ways in which these components may interact at different sites within the alimentary canal are discussed, as are the possible influences on mucosal immunity and the induction of oral tolerance. The possible systemic influences of absorbed saccharides at loci remote from the gut are considered in terms of inhibition of dietary and endogenous lectins, inhibition of bacterial attachment, and alteration of leukocyte homing behaviour. Finally, possible means by which dietary carbohydrates might modify various specific diseases are considered. CONCLUSIONS: It is probable that dietary carbohydrates can alter the equilibria between lectins, secretory IgA and micro-organisms in the alimentary canal, and this consideration could be exploited to promote health. The possible effects of dietary saccharides on allergy/oral tolerance or on recognition events at gut-remote sites warrant further investigation.
Role of complement in the toxicity of dietary legumes.
Med Hypotheses 1978 Mar-Apr;4(2):97-100
On the basis of in vivo data Jayne-Williams (1) has proposed that the toxicity of dietary legumes is due to their content of lectins which are immunosuppressive. On the basis of in vitro data with cultured lymphocytes (2), it is now proposed that ingested lectins bind to cell surfaces and cause autologous complement components to bind to and destroy immunologically competent cells. The hypothesis throws a possible light on the aetiology of favism and Whipple's disease.
Effect of dietary sub-lethal doses of lima bean lectin on relative organ weights, pancreatic and intestinal trypsin (EC 220.127.116.11) and chymotrypsin (EC 18.104.22.168) in the rat.
Department of Animal Production and Health, Federal University of Technology, Akure, Nigeria.
The dietary implications of feeding sub-lethal doses of extracted and purified lectin from lima bean were assessed in weanling rats using changes in relative organ weights, pancreatic and intestinal trypsin and chymotrypsin activities as the response indices. Liver weights decreased significantly (p less than 0.05) while the heart showed a slight but non-significant increase in response to dietary lectin levels. The kidneys, pancreas and spleen were not significantly affected by dietary lectin. Although the activities of the pancreatic enzymes tended, for the most part, to decrease with increasing dietary lectin, such decreases were not significant when compared with the control.
Dietary antigens and primary immunoglobulin A nephropathy.
J Am Soc Nephrol 1992 Apr;2(10 Suppl):S173-S180
Coppo R, Amore A, Roccatello D
Nephrology and Dialysis Department, Regina Margherita Children's Hospital, Turin, Italy.
To investigate the role of dietary components in immunoglobulin A mesangial nephropathy (IgAGN), this study focused on gliadin, based on the reported association between coeliac disease and IgAGN as well as the pilot observation that a gluten-free diet was able to reduce the levels of circulating IgA immune complexes (IgAIC). Several gluten lectinic fractions modulate leukocyte oxidative metabolism, cytotoxicity, and chemotaxis. In IgAGN patients, serum IgA to dietary Ag were sporadically positive and IgAIC containing IgA to dietary components were significantly increased. The affinity of serum IgA to various lectins was increased in some patients. A gluten-free diet, given to IgAGN patients with high levels of circulating IgAIC and positive antigliadin IgA, was followed by a decrease in the mean levels of both IgAIC and IgA to various dietary Ag, parallel to a reduction in proteinuria. These data suggest that dietary components, such as Ag or lectins, may play a role in IgAGN by promoting IgAIC formation and perhaps favoring mesangial localization via lectinic interactions.
Natural human antibodies to dietary lectins.
FEBS Lett 1996 Nov 18;397(2-3):139-142
Tchernychev B, Wilchek M
Department of Membrane Research and Biophysics, The Weizmann Institute of Science, Rehovot, Israel.
Natural antibodies to self and non-self proteins, including dietary proteins, are a significant part of the immune repertoire of humans. Antibodies to three structurally related legume lectins (Erythrina corallodendron lectin (ECorL), peanut agglutinin (PNA), and soybean agglutinin (SBA)) and to one cereal lectin (wheat germ agglutinin (WGA)) were purified by affinity chromatography from human sera and their binding specificity examined. The anti-SBA, anti-ECorL and anti-WGA antibodies exhibited high specificity, whereas the anti-PNA antibodies were polyreactive. Although the anti-WGA antibodies were highly specific for WGA, they also crossreacted with some other proteins. Although the anti-SBA and anti-ECorL antibodies both exhibited specificity when interacting with native lectins, they bound to a wider range of denatured lectins, indicating a common or universal epitope which is recognized by many natural antibodies. Interestingly, the natural antibodies did not interfere with the agglutination properties of the lectins. These findings may provide a basis for studying the in vivo biological effects of anti-dietary protein antibodies, including those against carbohydrate-binding proteins.