| PrefaceNanosized particles means the size of the particle at the range of 0. 1 ~ 100nm. When the macroscopic object is made into nanosized particles, its physical and chemical property change greatly compared with the normal materials. Nanosized materials are widely used in many fields such as chemical industry, medical, biology and so on. On the other hand, nanosized materials have more chance to pass bio - membrane because of its small size. The huge specific surface area enlarge the ability of combine with biomacromolecule and appear new toxicity.Nanosized materials emerge free radical then cause oxide damage on biological membrane, DNA, protein or other macromolecular. The bio - effect varies as the particle size change. Different chemical modification to a same material causes different toxicities. The same nanosized material acts different toxic effect in different genus animals. There is a lot of pathway for nanosized material to in-gression body. Among them respiratory passage touch is one of the main path. But the research on immune toxicity caused by inhalation of nanosized particles was rare.According to the special property of nanosized particles this research observe the toxic effect of nanosized and micronsized silicon dioxides on immune system in mice. Animals exposed to the ultrafine particles in a slow and repeated process to simulate the exposure of human to the ultrafine dusts.Materials and Methods1. Animals and treatmentAdult health Kunming strain mice were divided randomly into five groups; control group, μm - SiO250mg/m3 group, μm - SiO2200mg/m3 group, nano -SiO250mg/m3 group, nano -SiO2200mg/m3 group. Mice were exposed to particles of nanosized and micronsized silicon dioxides once every two days and two hours for each time. The volume of the all - glass whole - body inhalation chambers was 50 liters, for 28 days The volume of inhalation chambers is 50 liters. Mice were fed a rodent chow and water adlibitum. The experiment lasted 28 days and mice were sacrificed at the end of the exposure.2. Observation and determination2.1 Body weight and thymus, spleen, liver and lung viscera coefficient.2.2 T - lymphocytes function was determined by blastogenic response induced by the mitogen, concanavalin A (Con A) , of spleen lymphocytes. MTT spectrometry method was used.2.3 The cell examination of analysis was determined by Quantitative Hemolysis Spectrophotometry (QHS) method.2.4 Contents of immune globulin IgG,IgM,IgA in serum were determined by enzyme linked immunosorbent assay.2. 5 Engulfment functions of peritoneal macrophage were determined by means of engulf neutral red spectrometry method.2.6 IstopathologyTissues selected for histopathological examination were fixed in 10% neutral buffered formalin, embedded in paraffin, sectioned at 3μm, and routinely stained with hematoxylin and eosin.3. Statistical analysisThe variances were analyzed by software SPSS 12.0 and the experiment data were analyzed by One - way ANOVA procedure to assess the significance of treatment effects. And comparisons between every two groups were made by LSD -t test. The results were regarded as significant as P <0.05.Results1. Body weight and viscera coefficients of thymus, spleen, liver, andlung.There was no difference of body weight among all groups ( P > 0.05 ). Viscera coefficients of thymus in treated groups were significantly lower than that of the control group(P <0.01) , but there is no difference among different treated groups. Viscera coefficients of spleen and liver in nm - SiO2200mg/m3 dosage group were higher than those of the control group and other treated groups (P < 0.01). There was no difference of viscera coefficient of lung between every two treated groups ( P > 0.05 ).2. The effects of nanosized and micronsized silicon dioxides on the proliferation function of T — lymphocytes in mice.The proliferation function of T - lymphocytes in micronsized treated groups was significantly weaker than that of the control group( P <0. 01) , while there were no significant difference between the nanosized treated groups and the control group( P > 0.05 ). At both dosage, the proliferation function of T - lymphocytes in nanosized treated groups were higher than those of micronsized treated groups (P<0.01).3. The effects of nanosized and micronsized silicon dioxides on excretion function of antibody in mice.Except for the μm - SiO2 200mg/m3 group, excretion function of antibody in treated groups was significantly lower than that of the control group (P <0. 01). Excretion function of antibody in μm - SiO2 200mg/m3 group was lower than that of μm - SiO2 50mg/m3 group ( P < 0. 01). There was no significant difference of excretion function of antibody between nm - SiO2 50mg/m3 group and nm - SiO2 200mg/m3 group.4. The effects of nanosized and micronsized silicon dioxides on the contents of immune globulin IgG, IgM, and IgA in serum in mice.4.1 The effects of nanosized and micronsized silicon dioxides on the contents of IgG in serum in mice.At the 28 th days of exposure, the contents of IgG in serum of μm - SiO2 50mg/m3 group showed the tendency to increase compared with that of the control group( P = 0. 06 ). The contents of IgG of nm - SiO2 50mg/m3 group was significantly lower than those of the control group and other treated groups (P <0.01). There was no significant difference in contents of IgG in serum between micronsized silicon dioxide groups and the control group. But the contents of IgG in serum of nm - SiO2 50mg/m3 group kept on increasing since the 7th day, till the 21st and 28 th day it has been significantly higher than that of the pre - exposure ( P < 0.05 and P < 0.01, respectively ).4.2 The effects of nanosized and micronsized silicon dioxides on contents of IgM in serum in mice.There was no significant difference of the contents of IgM in serum among all groups at the 28th days of exposure (P >0.05). The contents of IgM in serum of groups were all decreased compared with that of pre - exposure during the first 14 days, and at the 14th day those of all groups were significantly lower than that of the pre - exposure(P <0.05). However, at the 21st day, the contents of IgM in serum of the control group was significantly lower than that of the pre - exposure ( P < 0. 01) , and nm - SiO2 50mg/m3 group was significantly higher than that of the pre - exposure( P < 0.05 ).4. 3 The effects of nanosized and micronsized silicon dioxides on contents of IgA in serum in mice.There was no significant difference of contents of IgA in serum among all groups at the 28th days of exposure ( P > 0. 05 ). The contents of IgA in serum of the control group and nm - SiO2 50mg/m3 group were significantly higher than those of the pre - exposure ( P <0.05). Other treated groups showed the tendency to increase compared with that of the pre - exposure, and there was no significant difference between them( P > 0.05 ).5. The effects of nanosized and micronsized silicon dioxides on engulfment function of macrophages in mice.Engulfment function of macrophages of nanosized treatment groups and μm - SiO2 200mg/m3 group was significantly lower than that of the control group ( P < 0.01). Engulfment function of macrophages of μm - SiO2 200mg/m3 was lower than that of μm - SiO2 50mg/m3 group( P < 0.01).6. The histopathological examination.6.1 The histopathological examination of the thymus.The lymph cell structure in the cortex of thymus in the control group was...
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