Walker Ulrich A, Warnatz Klaus
Division of Rheumatology and Clinical Immunology, Freiburg University Hospital, Freiburg, Germany.
Curr Opin Rheumatol. 2006 Jul;18(4):389-95. doi: 10.1097/01.bor.0000231908.57913.2f.
A severe decrease of CD4 T cells predisposes humans to opportunistic infections. In adults, HIV is certainly the most common cause of CD4 lymphocytopenia, but other causes, such as infections, autoimmune diseases, immunosuppressive therapy, lymphoma and idiopathic forms need to be considered. This review summarizes the current knowledge of the poorly understood syndrome of idiopathic CD4 lymphocytopenia.
Little research has tried to systematically dissect this probably heterogeneic syndrome after its initial description in 1992. Numerous cases presenting with opportunistic infections have been reported. Disturbed differentiation of stem cell precursors may contribute to CD4 lymphocytopenia. Because infections and lymphoma may also cause CD4 lymphocytopenia, the distinction between cause and effect may evolve only during follow-up.
The manifestation of opportunistic infections calls for the evaluation of the immune system for CD4 lymphocytopenia. The differential diagnosis of this condition in adults comprises primarily HIV infection and less often other diseases or drugs. Idiopathic CD4 lymphocytopenia is very rare. The clinical significance of low CD4 cell counts in HIV negative patients still awaits its systematic analysis. Prophylaxis of opportunistic infections is oriented at the recommendations of HIV-infected individuals and causal treatment remains experimental.
CD4 T细胞的严重减少使人类易患机会性感染。在成年人中，HIV无疑是CD4淋巴细胞减少最常见的原因，但也需要考虑其他原因，如感染、自身免疫性疾病、免疫抑制治疗、淋巴瘤和特发性形式。本综述总结了目前对了解甚少的特发性CD4淋巴细胞减少综合征的认识。
自1992年首次描述以来，很少有研究试图系统地剖析这种可能异质性的综合征。已报道了许多伴有机会性感染的病例。干细胞前体的分化紊乱可能导致CD4淋巴细胞减少。由于感染和淋巴瘤也可能导致CD4淋巴细胞减少，因果关系的区分可能仅在随访过程中才会明确。
机会性感染的表现需要评估免疫系统是否存在CD4淋巴细胞减少。成人这种情况的鉴别诊断主要包括HIV感染，其他疾病或药物导致的情况较少见。特发性CD4淋巴细胞减少非常罕见。HIV阴性患者CD4细胞计数低的临床意义仍有待系统分析。机会性感染的预防遵循针对HIV感染者的建议，病因治疗仍处于试验阶段。
