D'Orsogna Lloyd J, Krueger Rom G, McKinnon Elizabeth J, French Martyn A
Department of Clinical Immunology and Immunogenetics, Royal Perth Hospital, Perth, WA 6847, Australia.
AIDS. 2007 Aug 20;21(13):1747-52. doi: 10.1097/QAD.0b013e32828642c7.
To determine if the depletion of IgM memory B cells might contribute to the increased susceptibility of HIV patients to pneumococcal infection, memory B-cell subpopulations were investigated in HIV patients, including patients receiving antiretroviral therapy (ART).
Blood B cells with the phenotype of IgM memory B cells (CD27, IgM) and switched memory B cells (CD27, IgM) were measured in antiretroviral-treated (n = 32) and untreated (n = 24) HIV patients and non-HIV controls (n = 35). Serum levels of IgG and IgG2 antibodies to pneumococcal polysaccharides, IgG, IgG subclasses, IgM and IgA were also assayed in HIV patients.
Switched memory B-cell counts were lower than controls in HIV patients (P < 0.01) irrespective of antiretroviral status and correlated with CD4 T-cell counts (r = 0.56, P = 0.001) in treated patients. In untreated patients, IgM memory B-cell counts correlated with CD4 T-cell counts (r = 0.73, P < 0.0001) reflecting higher values than controls in patients with CD4 T-cell counts greater than 300 cells/microl (P = 0.004) and lower values than controls in patients with CD4 T-cell counts below 300 cells/microl (P = 0.0001). There was no relationship between serum levels of pneumococcal antibodies and IgM or switched memory B cells.
The depletion of IgM memory B cells in untreated HIV patients with a CD4 T-cell count below 300 cells/microl might be a risk factor for pneumococcal infection. The depletion of switched memory B cells is a complication of HIV infection irrespective of ART and might contribute to impaired IgG antibody responses. Memory B-cell subpopulations might predict the risk of pneumococcal sepsis more accurately than the CD4 T-cell count or pneumococcal antibody levels.
为了确定IgM记忆B细胞的耗竭是否可能导致HIV患者对肺炎球菌感染易感性增加，对HIV患者（包括接受抗逆转录病毒治疗（ART）的患者）的记忆B细胞亚群进行了研究。
在接受抗逆转录病毒治疗的HIV患者（n = 32）、未接受治疗的HIV患者（n = 24）和非HIV对照者（n = 35）中，检测具有IgM记忆B细胞（CD27⁺、IgM⁺）和类别转换记忆B细胞（CD27⁺、IgM⁻）表型的血液B细胞。还对HIV患者的肺炎球菌多糖IgG和IgG2抗体、IgG、IgG亚类、IgM和IgA的血清水平进行了检测。
无论抗逆转录病毒治疗状态如何，HIV患者的类别转换记忆B细胞计数均低于对照组（P < 0.01），且在接受治疗的患者中与CD4 T细胞计数相关（r = 0.56，P = 0.001）。在未接受治疗的患者中，IgM记忆B细胞计数与CD4 T细胞计数相关（r = 0.73，P < 0.0001），CD4 T细胞计数大于300个细胞/微升的患者其计数高于对照组（P = 0.004），而CD4 T细胞计数低于300个细胞/微升的患者其计数低于对照组（P = 0.0001）。肺炎球菌抗体的血清水平与IgM或类别转换记忆B细胞之间无相关性。
CD4 T细胞计数低于300个细胞/微升的未接受治疗的HIV患者中IgM记忆B细胞的耗竭可能是肺炎球菌感染的一个危险因素。类别转换记忆B细胞的耗竭是HIV感染的一种并发症，与ART无关，可能导致IgG抗体反应受损。记忆B细胞亚群可能比CD4 T细胞计数或肺炎球菌抗体水平更准确地预测肺炎球菌败血症的风险。
