Cellular immune response in intestinal villi of rats after consumption of onion (Allium cepa L.)

INSANI, E.M.; MIGNAQUI, A.C.; SALOMÓN, V.M.; PAZOS, A.A.; PIGHIN, D.G.; SUCAR, S.; SLOBODIANIK, N.; ROUX, M.E.

Zilina. Eslovaquia

Conferencia; International Scientific Conference on Nutraceuticals and Functional Foods. Food and Function 2009; 2009

Mucosal epithelia are primary sites for antigen entry. The microenvironment in these mucosal barriers has a marked influence on the immune response that ultimately ensues. The bioactive compounds present in foods would have an impact on the immuno-competence, especially in the intestinal villi (IV). In this way, the attention is focussed on the possibility of modulating the immune response for enhancing health and quality life. Allergy problems due to dietary factors were increased during the last years almost at epidemic levels. It is known that polyphenols and soluble dietary fiber, such as Fructo-oligo-saccharides (FOS), have some effects related to immune response but results are partial and controversial. Immunoglobulin E (IgE) has a central role in allergic responses and Secretory Immonoglobulin A (SIgA) is important to generate immune protection without inflammation. Onion is a food that presents a remarkable combination of bioactive compounds with high content of Quercetin (polyphenol) and FOS. The aim of this work was to evaluate ex vivo the effect of consumption of onion on cellular immune responses in IV. An experimental model was used to evaluate the effect of protein malnutrition and allergy response. Weanling rats of wistar strain were fed a protein-free diet until they lost 25% of their initial body weight. Re-feeding was performed by the administration of an experimental diet containing 20% casein as the only source of protein (Re-nourished group=R). Another Re-nourished group received this experimental diet plus onion juice added to drinking water (R+O) in quantity equivalent to normal consumption of an adult man, during 40 days.  Two well-nourished groups were used as normal controls (C) which were fed with standard commercial diet or the same diet plus onion juice (C+O). IgA+ and IgE+ B cells, CD5+ T cells and CD4+ T sub-population in IV were assessed by indirect immunofluorescence technique. Results: 1)T lymphocytes on intestinal Lamina Propria showed no significant difference neither for CD5 nor CD4 helper sub-population 2)IgA+ B lymphocytes showed no significant difference in R related to onion consumption (R+O). 3) Instead, IgE+ B cells were increased in R (165±7) as compared to C (62±7) probably due to the administration of the experimental diet in this model of malnutrition. The IgE+ B cells population was significantly decreased in R+O (79±9; p<0.0001) arriving to the levels of the well-nourished group (C). This indicates that onion would have a potential immuno-regulatory effect in allergic processes.