卡氏肺孢子虫感染的实验研究

EXPERIMENTAL STUDY OF PNEUMOCYSTIS CARINII INFECTION IN RATS

为探索卡氏肺孢子虫肺炎的发病机制，将大鼠分为实验组和对照组。给予实验组大鼠肌注地塞米松以诱发肺孢子虫肺炎。每周剖杀，光镜及电镜下对其两组大鼠肺组织进行病原学和病理学观察。对照组大鼠健康，第８ｗｋ后体重增加４５％，肺组织未见病理改变，亦未观察到卡氏肺孢子虫。实验组大鼠慢性发病，第８ｗｋ后体重比原来减少约２６％。电镜下第４ｗｋ、光镜下第５ｗｋ开始查见卡氏肺孢子虫，第７～８ｗｋ达重度感染，阳性率为６６．７％。该虫在肺泡腔内多见，肺间质中少见，在中性粒细胞、肺泡巨噬细胞和Ⅱ型肺泡上皮细胞内也见到。肺组织在实验前４ｗｋ几乎没有什么改变，第５～６ｗｋ有少量虫体附着于肺泡壁，第７～８ｗｋ表现为卡氏肺孢子虫肺炎的典型组织病理学改变。大滋养体伸出丝状伪足与Ⅰ型上皮细胞粘连，该处上皮细胞发生变性改变，Ⅱ型上皮细胞发生凋亡。

The rats were injected intramuscularly with dexamethasone and were sacrificed weekly to examine their lungs under light and electron microscopy. The rats in control group appeared healthy and their weights increased by 45% after 8 weeks, with no Pneumocystis carinii detected in their lungs. The rats in experimental group became chronically ill and lost about 26% of their original weight after 8 weeks. The positive rate of Pneumocystis carinii by Giemsa staining was 66.7% in the lungs of these rats. The large number of Pneumocystis carnii gave been in alveolar space and a few in alveolar interstitium, but they were found in the neutrophil, pulmonary macrophage and type Ⅱ alveolar epithelial cell. At the 5th week, few alterations were noted in their lung tissues. At the 7th to 8th week, when the infection reached the peak intensity on light microscopy, the typical features of pneumocystis pniumonia were found. The large trophozoites with filopodina were directly attached to the type Ⅰ pneumocyte. The type Ⅰ and Ⅱ pneumocyte revealed respectively degeneratine charges and apoptosis.