卡氏肺孢子虫感染的免疫诊断研究

目的：探讨肺泡灌洗液、血清抗原及血清抗体检测诊断卡氏肺孢子虫感染的价值。方法：利用免疫抑制大鼠模型及双夹心ＥＬＩＳＡ法检测不同时期感染大鼠肺泡灌洗液和血清中肺孢子虫抗原，用ＩＦＡ法检测血清中的肺孢子虫ＩｇＧ抗体，并与病原学检查结果进行比较。结果：感染大鼠肺泡灌洗液的抗原检测于免疫抑制６－８ｗｋ后均呈阳性，而对照组大鼠均呈阴性；大多数感染大鼠血清抗原检测为阴性；正常大鼠血清中有低滴度肺孢子虫ＩｇＧ抗体，感染大鼠抗体滴度轻度升高或不升高，但中止免疫抑制后血清抗体滴度明显升高，而肺泡灌洗液中抗原逐渐阴转。结论：肺泡灌洗液抗原检测可用于肺孢子虫感染的诊断，但血清中很难检出这种抗原；血清ＩｇＧ抗体的上升并不表示为现症感染。

STUDIES ON IMMUNOLOGICAL DIAGNOSIS OF PNEUMOCYSTIS CARINII INFECTION *

AIM: To assess the diagnostic value of Pneumocystis carinii(PC) antibodies and circulating antigens detection in alveolar lavage fluid(ALF) and serum. METHODS: The immunosuppressive rat model was used in this study. The PC antigens in both ALF and sera were detected by double sandwich ELISA, and the specific IgG antibody levels in sera were detected by IFA at different times after immunosuppression treatment. The detection results were compared with the corresponding results of PC finding in lung impression smear. RESULTS: The PC antigens in ALF were positive in all infected rats 6-8 weeks after immunosuppression while in control rats were all negative. By comparison, the PC antigens detected from sera were negative in most infected rats. During immunosuppression treatment with steroid, antibody titers in the infected rats rose slightly in some rats. After steroid was withdrawn, PC antigens in ALF became negative gradually but antibody titers rose progressively with time in all rats. CONCLUSION: Detecting PC antigens in ALF may be useful for diagnosing PC infection but these antigens were difficult to be detected in serum. The rise in serum IgG antibody does not necessarily indicate an existing infection.