Anaphylactic reaction in experimental malnutrition

We evaluated the effects of malnutrition on the allergic response in male EPM-1 Wistar rats. The animals underwent two dietary regimens from the 21st to the 60th day of life as follows: control animals were fed a normoproteic diet (18% casein) and malnourished animals a hypoproteic diet (4.5% casein). On day 60, some of the animals were sacrificed for determination of total serum protein and albumin levels. In addition, within each subgroup of the remaining animals, some underwent intraperitoneal immunization with ovalbumin in aluminum hydroxide. Thus, four groups of animal were obtained: immunized controls (n = 11); immunized malnourished animals (n = 11); unimmunized controls (n = 7) and unimmunized malnourished rats (n = 8). Fourteen days after sensitization with ovalbumin, the animals were challenged with intravenous ovalbumin in order to induce an anaphylactic reaction, which was evaluated by vascular permeability increase as assessed by the Evans blue dye extravasation method. Extravasation of Evans blue was quantitated in dried gastrointestinal tissues obtained from rats sacrificed 10 min after induction of the anaphylactic reaction. Passive cutaneous anaphylaxis (PCA) reactions were also evaluated in the controls and malnourished rats. The adequacy of our model was confirmed by the reduction in weight gain, in food intake, and in total protein and albumin serum levels in malnourished rats as compared to controls at 60 days of life. The anaphylactic reaction induced significant increase in vascular permeability particularly among control animals. PCR results showed significantly lower titers in malnourished animals when their sera were injected into the skin of control animals. In contrast, PCA reactions using sera from immunized control rats to inject into the skin of malnourished rats showed an equally intense reaction as that observed in control animals. Our results suggest that malnourished animals have a normal capacity of releasing inflammatory mediators, and show a normal vascular response after anaphylaxis. The diminished vascular response seen in the gastrointestinal tract in malnourished animals, as compared to controls, may be due to the production of lower levels of IgE antibodies caused by malnutrition.