Sridevi K, Neena Khanna, Chitralekha K T, Arif A K, Tomar D, Rao D N
Department of Biochemistry, All India Institute of Medical Sciences (AIIMS), Ansari Nagar, New Delhi-110029, India.
Int Immunopharmacol. 2004 Jan;4(1):1-14. doi: 10.1016/j.intimp.2003.09.001.
In leprosy, cell-mediated immunity (CMI) is more significant than humoral response to eliminate intracellular pathogen. T cell defect is a common feature in lepromatous leprosy (LL) patients as compared to tuberculoid type (TT) patients. For efficient initiation of CD4+, T cell response requires T cell receptor (TCR) activation and costimulation provided by molecules on antigen-presenting cells (APC) and their counter receptors on T cells. In our previous study, the defective T cell function in LL patients was restored to a proliferating state with the release of TH1 type cytokines using mycobacterial antigen(s) with two immunomodulators (Murabutide (MDP-BE) and T cell epitope of Trat protein of Escherichia coli) by presenting the antigen in particulate form in vitro to PBMC derived from leprosy patients. This observation prompted us to study the expression of the costimulatory molecules (CD80, CD86, CD28, CD152), other accessory molecules (TCR alphabeta/gammadelta) and T cell lineage molecules (CD4+ and CD8+) during constitutive and activated state of peripheral blood mononuclear cells (PBMC) derived from normal and leprosy individuals using different formulations of Mycobacterium leprae total cell wall antigen (MLCWA), Trat and MDP-BE using flow cytometric analysis. An increased surface expression of CD80, CD86 and CD28 but decreased CD152 expression was observed when PBMC of normal, BT/TT (tuberculoid) and BL/LL (lepromatous) patients were stimulated in vitro with MLCWA+MDP-BE+Trat peptide using liposomal mode of antigen delivery, while opposite results were obtained with the antigen alone. Antibody inhibition study using antihuman CD80 or CD86 completely abolished the T cell lymphoproliferation, thereby reconfirming the importance of these costimulatory molecules during T cell activation/differentiation. Though the liposome-entrapped antigen formulation has no effect on expression of alphabeta/gammadelta T cell receptor, the constitutive levels of TCR gammadelta were high in lepromatous patients. Thus, TCR bearing gammadelta appears to have a negligible regulatory role in peripheral blood of leprosy patients. The percentage of cells positive for CD4+ are increased in inducible state in all the three groups, while CD8+-positive cells were decreased in LL patients, thereby reconfirming the fact that priming of CD4+ cells are necessary for producing final effector functions. Lastly, intracellular cytokine staining experiment indicated that CD4+ cells are the major producers of IFN-gamma but not NK cells. The study highlights the reversal of T cell anergy especially in lepromatous patients through the modulation of costimulatory molecule expression under the influence of Th1 cytokines, i.e., IL-2 and IFNgamma.
在麻风病中，细胞介导的免疫（CMI）对于清除细胞内病原体比体液反应更为重要。与结核样型（TT）患者相比，T细胞缺陷是瘤型麻风（LL）患者的一个常见特征。为了有效启动CD4⁺ T细胞反应，需要T细胞受体（TCR）激活以及抗原呈递细胞（APC）上的分子及其T细胞上的对应受体提供的共刺激。在我们之前的研究中，通过在体外将抗原以颗粒形式呈递给麻风病患者来源的外周血单个核细胞（PBMC），使用含有两种免疫调节剂（Murabutide（MDP - BE）和大肠杆菌Trat蛋白的T细胞表位）的分枝杆菌抗原，LL患者中缺陷的T细胞功能恢复到增殖状态，并释放TH1型细胞因子。这一观察结果促使我们使用流式细胞术分析，研究来自正常人和麻风病患者的外周血单个核细胞（PBMC）在组成性和激活状态下，使用不同配方的麻风杆菌全细胞壁抗原（MLCWA）、Trat和MDP - BE时共刺激分子（CD80、CD86、CD28、CD152）、其他辅助分子（TCR αβ/γδ）和T细胞谱系分子（CD4⁺和CD8⁺）的表达。当正常、BT/TT（结核样型）和BL/LL（瘤型）患者的PBMC在体外使用脂质体抗原递送模式用MLCWA + MDP - BE + Trat肽刺激时，观察到CD80、CD86和CD28的表面表达增加，但CD152表达降低，而单独使用抗原时则得到相反的结果。使用抗人CD80或CD86的抗体抑制研究完全消除了T细胞的淋巴细胞增殖，从而再次证实了这些共刺激分子在T细胞激活/分化过程中的重要性。尽管脂质体包裹的抗原制剂对αβ/γδ T细胞受体的表达没有影响，但瘤型患者中TCR γδ的组成性水平较高。因此，携带γδ的TCR在麻风病患者外周血中的调节作用似乎可以忽略不计。在所有三组中，诱导状态下CD4⁺阳性细胞的百分比增加，而LL患者中CD8⁺阳性细胞减少，从而再次证实了启动CD4⁺细胞对于产生最终效应功能是必要的这一事实。最后，细胞内细胞因子染色实验表明，CD4⁺细胞是IFN - γ的主要产生者，而不是NK细胞。该研究强调了通过在Th1细胞因子即IL - 2和IFNγ的影响下调节共刺激分子表达，尤其是在瘤型患者中逆转T细胞无反应性。
