Natural Antibodies to Dietary Components (Pages 25-34)
Y.P. Venkatesh and V. Prasanna Kumar
Department of Biochemistry and Nutrition, CSIR–Central Food Technological Research Institute, Mysore, Karnataka, India
Abstract: Natural antibodies (NAbs), present in the serum of vertebrates, are defined as antibodies that are produced without any previous infection, vaccination, foreign antigen exposure or passive immunization. They can activate the classical pathway of complement leading to lysis of enveloped viral particles long before the adaptive immune response comes into play. Many NAbs are directed against the disaccharide Gal-α-1,3-Gal (abbreviated as α-Gal), which is found as a terminal sugar on glycosylated cell surface proteins, and are generated in response to production of this disaccharide by the human gut bacteria. NAbs have been found to several self-antigens including the human ABO blood group antigens. NAbs have been shown to exhibit ‘polyreactivity’ or ‘oligoreactivity’ with several antigens including some self-antigens. Since human gastrointestinal system is exposed to a wide variety of food antigens, study of NAbs to various dietary components in humans is important as it may provide information about food components that are more likely to be immunogenic. Further, NAbs to dietary components may provide immediate immune response for combating bacterial and viral infections. Among the dietary proteins, several lectins/agglutinins (garlic, soybean, peanut, banana and wheat germ) have been shown to induce NAbs in healthy humans, besides other proteins such as avidin, bromelain, lactoferrin and alliinase. Polysaccharides which have been reported to induce NAbs are pectic polysaccharides from some plants, β-glucans from yeast and teichoic acid from Gram-positive bacteria; in the case of cod, polymannuronic acid present in seaweed and chitosan induce NAbs. Foods supplemented with ω-3 fatty acids, phospholipids or soy components have been shown to increase the levels of NAbs to certain endogenous mediators and proteins in humans. The review also covers a short account of the significance of NAbs to dietary components.
Keywords: Carbohydrates, dietary components, dietary lectins, food proteins, natural antibodies, polysaccharides.