Studys Of Subchronic Aluminum Exposure On The Immunotoxicology Of Rats

Sixty healthy male Wistar rats (5 weeks old) weighed 110 g -120 g were randomly allocated into control-group (GC), low-dose group (GL), medium-dose group (GM) and high-dose group (GH). All the rats were acclimatized for one week before the test, and were orally exposed to 0, 64.18, 128.36 and 256.72 mg/kg body weight aluminum trichloride (AlCl₃) in drinking water for 120 days, respectively.The contents of trace element, cellular immune function, humoral immune function, and immune function of erythrocytes were studied by graphite furnace atomic absorption spectrophotometry, flame atomic absorption spectrophotometry, immunoturbidimetry, ANAE dye method, flow cytometry, and radio immunoassay(RIA) in rats. The microscopic and ultramicroscopic changes in spleen were observed. The results were shown as follows:1) Aluminum (Al) exposure model was made successfully in the rats by clinical symptom and physical change.2) Histopathologically, the spleen in GC, organization velamen and trabecula were obvious. And no effect was observed in white pulp, red pulp, boundary zone and germinal Center. But, in GH, the limitation between white pulp and red pulp was not obvoious; white pulp growed downwards; the number of lymphocytes and germinal Center decreased; the number of macrophage increased. Ultrastructurally, in GC, mitochondria, membrane, cristae, rough endoplasmic reticulum, free ribosomes and dictyosome were observed; in GH, the perinuclear cisterna of lymphocyte became widen, organelles in hyalomitome decreased, and few mitochondrias became swelling. It indicated that the structure of spleen in Al-treated groups was impared by Al exposure.3) The contents of Al and copper (Cu) was higher, and zinc (Zn) and iron (Fe) were lower spleen of rats in Al-treated groups than that in GC. It indicated that Al could accumulate in the spleen following long-time Al exposure. Al could interrupte the metabolism of trace element, and impared the immune function of spleen of rats in Al-treated groups.4) The contents of ANAE⁺, CD³⁺, CD⁴⁺, CD⁴⁺/CD⁸⁺in peripheral blood, IL-2 and TNF-αin serum were lower, and the content of CD⁸⁺ was higher in Al-treated groups than that in GC. It indicated that Al exposure suppressed the cellular immune function of rats.5) The levles of immunoglobulin (Ig) G, and IgA in Al-treated groups increased, and the content of IgM in Al-treated groups decreased. It indicated that Al exposure disordered the humoral immune function of rats in Al-treated groups.6) The levels of complement factor 3 (C₃) and C₄ in serum of rats were lower than that in GC. And the level of IgE was higher than that in GC. It indicated Al induced allergic response in Al-treated groups.7) The levels of erythrocytes C_3b receptor rate (RBC-C_3bRR) and erythrocytes rosette forming enhancing rate (ERER) decreased, while the levels of erythrocytes C_3b immune complex rosette rate (RBC-ICR) and erythrocytes rosette forming inhibitory rate (ERIR) increased with the increases of Al content in drinking water. The results suggest that the immune function of erythrocytes in rats is suppressed by Al.