MALNUTRITION AND EXPERIMENTAL LUNG ALLERGY

Background Although it is commonly accepted that the immune response i s affected by malnutrition there are very few data about its effect in allergic diseases. Objective The aim of the present study was to inve stigate the effect of malnutrition in allergic lung inflammation. Meth ods An anaphylactic reaction was induced in rat lungs and the increase d vascular permeability was measured in the trachea, internal and exte rnal bronchi and parenchyma by the Evans blue extravasation method. Th ese studies were conducted in two dietary groups: one fed a normoprote ic diet (18%) and the other a hypoproteic diet (4.5%). When the animal s were 60 days old the group fed the hypoproteic diet presented a redu ction of 77.86% in bodyweight, 63.3% in food intake and 36% in plasma protein concentration characterizing a severe protein-calorie malnutri tion. Results The anaphylactic reaction in the lungs induced a signifi cant increase in vascular permeability in the trachea and bronchi of b oth dietary groups. However, the intensity of this effect was signific antly lower in the malnourished group. Analysis of immunoglobulin isot ypes in the serum by ELISA showed that whereas IgG1 and IgG2a levels w ere similar in both groups, the levels of IgE were significantly lower in the malnourished animals. Moreover, the levels of antigen-specific IgG1, IgG2a and IgE were all significantly inhibited by the protein-c alorie malnutrition. When antibodies were passively transfered to the malnourished rats, they developed a reaction as intense as the normopr oteic group. Conclusion These results suggest that the capacity to rel ease inflammatory mediators and the vascular response to these mediato rs is not affected by this type of malnutrition and, therefore, the di minished response of the airways reported here is probably due to the lower levels of anaphylactic antibodies produced by the malnourished r ats.