Mycoplasma pneumoniae (Mp) is a leading cause of human community-acquired pneumonia. To investigate the pathogenesis of the infection, 36 gerbils were intranasally inoculated with Mp culture (30 animals) or sterile mycoplasma broth (6 animals) and euthanized from 1 to 5 weeks post infection. A morphological and immunohistochemical study was carried out in all animals to determine the cellular populations present in lung parenchyma. Polyclonal and monoclonal antibodies were used to detect antigens of Mp and CD3, CD4, CD8 and CD79 lymphocytes, as well as cells containing S100 and major histocompatibility complex class II (MHC-II) antigens. There was progressive infiltration of mononuclear cells in the lamina propria of bronchi and bronchioles, and hyperplasia of the bronchus-associated lymphoid tissue (BALT) in the infected animals. BALT contained dendritic cells immunopositive to S100 and MHC-II and numerous CD3, CD4 and CD79 lymphocytes. The immunohistochemical results showed that T lymphocytes, particularly CD4 and CD79 cells, may play a role in the immune response of gerbils against Mp. This experimental model is valuable for investigation of the pathogenesis of Mp infection and may assist in the development of therapeutic strategies.

肺炎支原体(Mp) 是人类社区获得性肺炎的主要原因。为了研究感染的发病机制，将 36 只沙鼠鼻内接种 Mp 培养物（30 只动物）或无菌支原体肉汤（6 只动物），并在感染后 1 至 5 周实施安乐死。在所有动物中进行形态学和免疫组织化学研究以确定肺实质中存在的细胞群。多克隆和单克隆抗体用于检测 Mp 和 CD3、CD4、CD8 和 CD79 淋巴细胞的抗原，以及含有 S100 和主要组织相容性复合体 II 类 (MHC-II) 抗原的细胞。感染动物的支气管和细支气管固有层中存在单核细胞进行性浸润，支气管相关淋巴组织（BALT）增生。BALT 包含对 S100 和 MHC-II 呈免疫阳性的树突状细胞和大量 CD3、CD4 和 CD79 淋巴细胞。免疫组化结果表明，T 淋巴细胞，特别是 CD4 和 CD79 细胞，可能在沙鼠对 Mp 的免疫反应中发挥作用。该实验模型对于研究 Mp 感染的发病机制很有价值，可能有助于制定治疗策略。