The aim of this research was to compare the immune response after oral administration of quercetin(Reference Insani, Mignaqui and Pazos1) in mesenteric lymphoid nodes (MLN; inductive site) and lamina propria of intestinal villi (IV; effector site)(Reference Nagler-Anderson2).
An experimental model was used to evaluate the effect of protein malnutrition and allergic 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). Other experimental groups received this experimental diet plus quercetin (R+Q1 or R+Q2) (Q1=140 μg/kg body weight per d; Q2=280 μg/kg body weight per d; mean value), added to drinking water during 40 d. Three well-nourished groups were used as normal controls (C) which were fed with standard commercial diet or the same diet plus quercetin (C+Q1 and C+Q2). The MLN and small intestine were removed and properly processed, the last ones by Saint-Marie´s technique(Reference Saint Marie3). IgE+ B-cells were measured (Indirect Immunofluorescent Assay). The animal protocol was approved by the ethical committee of the University of Buenos Aires.
Results showed that in MLN R group presented higher % of IgE+ B-cells compared with C (42±2; 28±2) (P<0.0001). This value diminished to 17±2 in R+Q1, normalising the values under the normal control, C. With double dose of quercetin, R+Q2 was statistically lower than R but this dose resulted less efficient to diminish % of IgE+ B-cells (R+Q2=34±2) (Figs. 1 and 2).
In IV, the effector site of the immune response, R group presented the highest number of IgE+ B-cells reaching to 165±7 (C 62±7; P<0.0001). In this case, double dose of quercetin was more efficient for lowering IgE+ B-cells compared with Q1 (R+Q, 2 71±6; R+Q1, 99±6).
In conclusion, quercetin intake presented differential effect for IgE+ B-cells related to inductive or effectors sites of immune response. These findings have to be taken into account to describe the effect of bioactive compound of nutritional interest.