目的 研究高海拔地区老年社区获得性肺炎（CAP）患者体液免疫功能变化及其关系。方法 CAP患者分别在发病后24h、4d、7d、10d、15d、18d、23d以内检测血清IgG、IgA、IgM水平并与215名健康对照组进行比对分析。结果 CAP患者发病早期24h内血清IgG、IgA、IgM水平与健康对照组比较差异无统计学意义（P＞0.05），4d后血清IgG、IgA水平明显减低，与健康对照组比较差异有统计学意义（P＜0.01），且持续下降至15d，18d后血清IgG、IgA水平开始回升，23d血清IgG、IgA水平基本恢复正常，与健康对照组比较差异无统计学意义（P＞0.05）。结论 高海拔地区老年CAP患者以IgG、IgA水平降低为主，且持续时间长，老年CAP患者体液免疫功能变化与病情转归有比较密切的关系，调节免疫治疗，可能会缩短病程，改善预后和降低死亡率，对老年CAP的预防和治疗具有重要意义。

Objectives To explore the humoral immune function changes in old patients with community acquired pneumonia (CAP) in the high altitude localities. Methods The serum IgG, IgA and IgM levels in old patients with CAP and 215 cases of healthy control people were examined within 24h, at 4 day,7 day,10 day, 15 day, 18 day and 23 day. Results There were no significant changes on the serum IgG, IgA and IgM levels within 24 h in patients with CAP as compared with those of healthy control group（P＞0.05）. The serum IgG and IgA levels were significantly reduced at 4 day as compared with those of healthy control group （P＜0.01）, and continued to decline to 15 day. The serum IgG and IgA levels began to increase on 18 day. The serum IgG and IgA levels returned to normal levels on 23 day to compared with those of healthy control（P＞0.05）. Conclusion The serum IgG and IgA levels in old patients with CAP in high altitude area are decreased. This immune function changes with a long duration are closely related to the disease outcome. The immune therapy may shorten the course of disease, improve the prognosis and reduce mortality. It might have an important significance in the prevention and treatment of the elderly CAP.