Foodallergy, mainly caused by food proteins (antigens) occurs through cross-linkingof immunoglobulin isotype E (IgE) on the surface of mast and/or basophil cells 1.
This type of allergy may be different fromfood sensitivity that is caused by components of food such as lactose 2. Common food induced allergies includecereal-induced allergies, particularly wheat-induced allergies. It has beenwell documented that more than 400 allergens cause food allergies 3.
The sensitive individuals may experienceadverse reactions such as anaphylaxis and in some instances the reaction can belethal. Althoughmost of the proteins are degraded into non-immunogenic peptides whiletravelling through GI tract, but some proteins may escape and enter entericvasculature and cause allergy 4. One ofthe mechanism which helps them to escape may include aggregation, which occursafter exposing to high temperature. For instance, vicilin becomes resistance toproteolytic digestion after exposing to high temperature 5. On the contrary, high temperature canreduce the allergenic property of egg ovalbumin and ovomucoid 6. Proteins of such calibre which havesurvived during GI digestion, may bind and enter into the mucus-coveredepithelial cells or directly absorbed by immune cells and cause allergy 7.
Mostof the food allergies are due to legumes such as red kidney beans (Phaseolus vulgaris), peanut, soybeans,red gram, chickpea, black gram, green gram, lentils, fenugreek and green bean 8. Red kidney bean is a routinely consumedbean, which is reported to induce allergic reaction in many individuals 9, 10 and hence the allergenic potential ofred kidney bean is a matter of concern. Protein content of red kidney bean iscomposed of storage proteins such as phaseolin and other proteins includinglectins, arcelin and ?-amylase inhibitor 11–13. The lectin comprisingleucoagglutinating phytohemagglutinin (PHA-L) and erythroagglutinatingphytohemagglutinin (PHA-E) 12. Severalstudies regarding PHAs have been carried out to reveal blood grouping,erythrocyte polyagglutination activity, mitogenic stimulation of lymphocytes,lymphocyte subpopulation studies, fractionation of cells and other particles,histochemical studies of normal and pathological conditions 14, 15. Further, it was also found thatphaseolin and PHA can act as strong allergens causing serious anaphylaxisleading to leaky gut by interacting with glycans of intestinal cells 16.
This is the main cause for potentautoimmune destruction that can result when the intestinal lining experiencesthis level of damage. Hence it is very important to address an issue onallergic potential of PHA.Itis well documented that all of the lectins can be inhibited by their specificsimple/complex sugar derivatives 17These specific sugars can be found naturally either in free form or inconjugation with proteins know as glycoproteins.
Natural glycoproteins such asmucins which contain 80-85% of carbohydrates are potent molecules to inhibitactivity of lectins. Mucins are primary gel-forming components of mucusoccurring as major constituents of saliva which nearly accounts 60-70% of dryweight 18. Since PHA can be completely inhibited byinteracting with its cognitive complex sugar moieties/glycoproteins, it is thebest way to inhibit using these sugars/glycoproteins, before it could enterinto the digestive system and elicit allergic reactions. Given the fact thatlectins are effectively inhibited by glycoproteins and all the salivary mucinsare glycoproteins, we exploited these properties to identify whether anysalivary fraction from healthy normal could inhibit PHA activity effectively.If so, these salivary fractions can be purified to homogeneity, cloned andproduced in bulk and can be supplemented as food additives to minimize allergicimplications of PHA.