RESUMO
This study was undertaken to investigate the hypothesis that lipid peroxidation might be associated with immunological abnormalities in experimental hemosiderosis. The correlation between the degree of plasma and spleen lipid peroxidation with lymphocyte proliferative response and with the proportion of T lymphocyte subsets was studied in normal and iron overloaded male Sprague Dawley rats. The iron-loading protocol consisted of a total dose of iron-dextran (1.5 mg/Kg body weight) divided in daily i.m. injections over twenty consecutive days. Lipid peroxidation was measured by the thiobarbituric acid assay in plasma and in homogenates of spleen. Plasma lipid peroxide level increased rapidly after i.m. administration of iron-dextran and decreased sharply at 48 h after the last injection. Conversely, a progressive increase of lipid peroxidation in homogenates of spleen was observed in the course of the iron overload protocol, remaining high even at 50 days after initiation of iron-dextran injections. The increase of spleen lipid peroxide levels was associated with decreased lymphocyte proliferative response to Con A in iron overloaded rats. The addition of superoxide dismutase and catalase to lymphocyte cultures reversed the inhibition of the proliferative response, implicating reactive species of oxygen as the causative agents of these alterations. These effects may be related with the enhanced membrane and DNA damage occurring during intracellular and extracellular peroxidation. Negative correlations between helper/cytotoxic ratio and malondialdehyde levels were obtained in blood and spleen during iron administration. These results supports the hypothesis that lipid peroxidation plays a role in the immunological abnormalities observed in experimental hemosiderosis.
Assuntos
Hemossiderose/imunologia , Peroxidação de Lipídeos/efeitos dos fármacos , Ativação Linfocitária/efeitos dos fármacos , Subpopulações de Linfócitos T/efeitos dos fármacos , Animais , Catalase/farmacologia , Hemossiderose/metabolismo , Masculino , Ratos , Ratos Sprague-Dawley , Superóxido Dismutase/farmacologiaRESUMO
Iron and ferritin impair a variety of immunological functions. To evaluate the effect of ferritin iron content on rat lymphocyte proliferative response, isoferritins that differ in their iron content and isoelectric point (pI) were isolated from iron overload rat livers by ultracentrifugation (isoferritins with high iron content and low pI) or crystallization (isoferritins with low iron content and high pI) methods. Additionally, commercial horse splenic ferritin (with a lower pI and higher iron content than rat isoferritins) was also tested. Proliferative response to Con A was decreased in a dose-dependent manner in all assays in which spleen cells were incubated with rat and horse isoferritins. However, isoferritins with higher iron contents (rat isoferritin obtained by ultracentrifugation and horse ferritin) caused a greater decrease of proliferative response at 5 and 25 micrograms/ml than the others. Rat and horse apoferritins showed no inhibitory effect on lymphocyte proliferative response, suggesting that the effect is due to iron probably through the damaging effect of reactive oxygen species generated by iron released by the isoferritins on lymphocyte functions. Additionally, the role of serum ferritin level on proliferative response was studied in an experimental model of iron overload in rats. An inverse relationship between the proliferative response and serum ferritin levels was observed. Our results suggest that the inhibitory effect of the isoferritins on lymphocyte proliferative response is due, at least partially, to the iron content of this protein and not exclusively to variation in pI as suggested by other authors. These results are in agreement with the possible immunosuppressor role of ferritin in vivo.
Assuntos
Ferritinas/análise , Ferritinas/farmacologia , Hemossiderose/imunologia , Imunossupressores/farmacologia , Ferro/análise , Ativação Linfocitária/efeitos dos fármacos , Animais , Ferritinas/sangue , Ferritinas/isolamento & purificação , Cavalos , Ferro/fisiologia , Fígado/química , Masculino , Ratos , Ratos Sprague-DawleyRESUMO
Six black infants and young children with high titers of milk precipitins were identified by screening the sera of 160 children with idiopathic chronic lung disease. None of the six had immunoglobulin deficiency, elevation of sweat chlorides, SS hemoglobin, or recurrent aspiration. All six children had typical manifestations of milk-induced pulmonary hemosiderosis: recurrent pulmonary infiltrates (6/6), hemosiderin-laden pulmonary macrophages (5/6), intermittent wheezing (5/6), eosinophilia (4/6), anemia (4/6), iron deficiency (4/4), failure to thrive (4/6), and elevated levels of serum IgE (4/4). Three children also had chronic rhinitis and eventually developed large adenoids, hypercapnia and acidosis during sleep, and right heart failure. Elimination of cow milk from the diet, symptomatic therapy, and adenoidectomy when indicated resulted in improvement of all six patients. Pulmonary hemosiderosis and some cases of upper airway obstruction with pulmonary hypertension appear to be two stages, early and delayed, of the same immunophysiologic process. Early dietary intervention may prevent the cardiovascular complications of this process.