Cellular tropism of the human retrovirus HTLV-III/LAV. I. Role of T cell activation and expression of the T4 antigen.
Cellular tropism of the human retrovirus HTLV-III/LAV. I. Role of T cell activation and expression of the T4 antigen.
复制标题
人类逆转录病毒 HTLV-III/LAV 的细胞趋向性。
作者：
J. Mcdougal;A. Mawle;S. Cort;J. Nicholson;G. Cross;J. A. Scheppler;D. Hicks;J. Sligh
在感染了人类逆转录病毒HTLV - III/LAV的正常人淋巴细胞培养物中，可检测到的细胞质病毒在一定比例（1% - 10%）的细胞中出现然后消失，随后通过颗粒逆转录酶活性、病毒抗原测定和感染滴度检测到病毒释放。病毒感染与感染细胞上可检测到的T4抗原缺失有关，并最终导致培养物中T4⁺细胞完全缺失。残留的非T4⁺细胞对HTLV - III/LAV的二次感染不敏感，并且在分离的细胞群培养物中，大量的病毒复制发生在T4⁺ T细胞中，而在非T4⁺细胞中极少（如果有的话）发生。当用一组检测主要单核细胞类型（α - T11、α - T3、α - Mo2、α - B1）、功能性T细胞亚群（α - T8、α - Leu - 8、α - T17）或活化/增殖细胞（α - T10、α - Ia、α - T9、α - 4F2、α - Tac）的单克隆抗体监测淋巴细胞或纯化的T4⁺ T细胞的感染和未感染培养物时，我们未检测到细胞表面表型（除T4外）不成比例的缺失。在植物血凝素（PHA）刺激并在白细胞介素2（IL - 2）存在下培养的淋巴细胞中，HTLV - III/LAV的复制在数量上最多。一旦被PHA激活，非分裂（照射过的）细胞中的病毒产生与未照射细胞相似，但如果在PHA刺激前进行照射，则病毒产生会大幅减少。省略PHA、IL - 2或两者都会导致病毒复制量逐渐减少。然而，无论培养基补充物或照射情况如何，在所有培养物中都检测到病毒复制且T4⁺ T细胞减少。T4⁺ T细胞吸收感染性病毒，并且直接证明了HTLV - III/LAV与T4⁺ T细胞表面结合，而不与非T4⁺细胞结合。在活化和未活化细胞中以及在4℃和37℃时结合情况相同。用α - T4a单克隆抗体和病毒观察到结合的相互抑制。在HTLV - III/LAV接种前和接种过程中使细胞暴露于α - T4a可抑制随后的病毒复制。我们得出结论，T4⁺ T细胞是HTLV - III/LAV复制的主要靶细胞，这种嗜性与作为病毒结合位点的T4抗原的表达有关，无论亚群或活化状态如何，T4⁺ T细胞的感染都是不可避免的，并且细胞的活化/增殖状态不是感染性的必要决定因素，而是决定随后发生的复制量。
In cultures of normal human lymphocytes infected with the human retrovirus HTLV-III/LAV, detectable cytoplasmic virus appears and then disappears in a proportion (1 to 10%) of cells, followed by release of virus detected by particulate reverse transcriptase activity, virus antigen assay, and infectivity titer. Virus infection is associated with loss of detectable T4 antigen on infected cells and, ultimately, complete loss of T4+ cells from the culture. Residual non-T4+ cells are not susceptible to a second infection with HTLV-III/LAV, and in cultures of separated cell populations, substantial virus replication occurred in T4+ T cells and minimally, if at all, in non-T4+ cells. We could not detect a disproportionate loss of cell surface phenotype (other than T4) in comparison of infected and noninfected cultures of lymphocytes or purified T4+ T cells when these cultures were monitored with a panel of monoclonal antibodies that detect the major mononuclear cell types (alpha-T11, alpha-T3, alpha-Mo2, alpha-B1), functional T cell subsets (alpha-T8, alpha-Leu-8, alpha-T17), or activated/proliferating cells (alpha-T10, alpha-Ia, alpha-T9, alpha-4F2, alpha-Tac). HTLV-III/LAV replication was quantitatively greatest in lymphocytes stimulated with phytohemagglutinin (PHA) and cultured in the presence of interleukin 2 (IL 2). Once activated by PHA, virus production in nondividing (irradiated) cells was similar to that in nonirradiated cells, but was substantially reduced if radiation was performed before PHA stimulation. Omission of PHA, IL 2, or both resulted in progressively lower amounts of virus replication. However, virus replication was detected and T4+ T cell depletion occurred in all cultures, regardless of medium supplement or radiation. T4+ T cells absorb infectious virus, and the binding of HTLV-III/LAV to the surface of T4+ T cells, but not to non-T4+ cells, was directly demonstrated. Binding is equivalent in activated and nonactivated cells and at 4 degrees and 37 degrees C. Reciprocal inhibition of binding was observed with alpha-T4a monoclonal antibody and virus. Exposure of cells to alpha-T4a before and during HTLV-III/LAV inoculation inhibited subsequent virus replication. We conclude that T4+ T cells are the major target for HTLV-III/LAV replication, that this tropism is related to expression of the T4 antigen that serves as a binding site for virus, that infection is inexorable in T4+ T cells regardless of subset or activation state, and that the activation/proliferative state of the cells is not a necessary determinant of infectivity, but rather, determines the amount of replication that will ensue.