Pandolfi F, Boyle L A, Trentin L, Kurnick J T, Isselbacher K J, Gattoni-Celli S
Department of Pathology, Massachusetts General Hospital, Charlestown.
Cancer Res. 1991 Jun 15;51(12):3164-70.
Previous studies have suggested that, in human melanoma, expression of HLA-A2 antigen is important for tumor cell recognition by autologous T-lymphocytes. Because of the recent demonstration that expression of HLA Class I antigens may be selectively lost in several human tumors, including melanoma, we derived pairs of tumor infiltrating lymphocytes (TIL) and melanoma cell lines from 4 human lymphocytic antigen (HLA)-A2+ patients with metastatic melanoma. We observed that, although all 4 TIL cultures expressed HLA-A2 antigen, only 2 melanoma cell lines did so. Melanoma cells derived from the other 2 patients showed neither surface expression of the HLA-A2 antigen nor presence of the corresponding mRNA. We also observed some correlation between loss of HLA-A2 expression and level of c-myc transcription. TIL derived from patients whose melanoma cell lines had normal expression of HLA-A2 had a CD8 phenotype and were capable of lysing autologous melanoma cells. Melanoma cell killing was CD3 and major histocompatibility complex Class I restricted in both cases, but HLA-A2 restricted in only one case. On the other hand, TIL derived from the 2 patients whose melanoma cell lines had lost expression of HLA-A2 had a predominant CD4 phenotype and virtually no cytotoxic activity. Preincubation of the HLA-A2 negative melanoma cell lines with alpha- or gamma-interferon did not induce the re-expression of the HLA-A2 antigen. In an attempt to restore HLA-A2 antigen expression in one of the melanoma cell lines that were HLA-A2 negative, we transfected these cells with the HLA-A2 gene subcloned in the pSV2-neo vector. Four transfected clones, with high levels of HLA-A2 antigen expression, were expanded and characterized. Proliferative and cytotoxic activities of TIL against the autologous transfected clones as well as the untransfected parental melanoma cell line were measured and compared. CD4+ TIL showed no difference in the proliferative response to autologous parental and HLA-A2 transfected clones. However, we observed selective recognition of the HLA-A2 expressing clones by autologous cultured peripheral blood lymphocytes (which contained CD8 cells) as well as allogeneic CD8+ TIL with a HLA-A2 restricted pattern of recognition. In contrast, virtually no cytotoxic activity was detected against either parental or HLA-A2 transfected clones. Overall, our data suggest that selective down-regulation of HLA-A2 antigen expression in melanoma cells may represent one of the mechanisms by which tumor cells escape immunological recognition.
以往的研究表明，在人类黑色素瘤中，HLA - A2抗原的表达对于自体T淋巴细胞识别肿瘤细胞很重要。由于最近有证据表明，包括黑色素瘤在内的几种人类肿瘤中可能会选择性地丧失HLA I类抗原的表达，我们从4名转移性黑色素瘤的人类淋巴细胞抗原（HLA）- A2 +患者中获取了肿瘤浸润淋巴细胞（TIL）和黑色素瘤细胞系对。我们观察到，虽然所有4种TIL培养物都表达HLA - A2抗原，但只有2种黑色素瘤细胞系表达该抗原。来自其他2名患者的黑色素瘤细胞既没有HLA - A2抗原的表面表达，也没有相应的mRNA。我们还观察到HLA - A2表达缺失与c - myc转录水平之间存在一定相关性。黑色素瘤细胞系HLA - A2表达正常的患者来源的TIL具有CD8表型，并且能够裂解自体黑色素瘤细胞。在这两种情况下，黑色素瘤细胞的杀伤作用均受CD3和主要组织相容性复合体I类限制，但仅在一种情况下受HLA - A2限制。另一方面，黑色素瘤细胞系HLA - A2表达缺失的2名患者来源的TIL具有主要的CD4表型，几乎没有细胞毒性活性。用α - 或γ - 干扰素对HLA - A2阴性黑色素瘤细胞系进行预孵育，并未诱导HLA - A2抗原的重新表达。为了在其中一种HLA - A2阴性的黑色素瘤细胞系中恢复HLA - A2抗原的表达，我们用克隆于pSV2 - neo载体中的HLA - A2基因转染这些细胞。4个转染克隆具有高水平的HLA - A2抗原表达，对其进行了扩增和鉴定。测量并比较了TIL对自体转染克隆以及未转染的亲本黑色素瘤细胞系的增殖和细胞毒性活性。CD4 + TIL对自体亲本和HLA - A2转染克隆的增殖反应没有差异。然而，我们观察到自体培养的外周血淋巴细胞（其中包含CD8细胞）以及同种异体CD8 + TIL以HLA - A2限制的识别模式选择性识别表达HLA - A2的克隆。相比之下，对亲本或HLA - A2转染克隆几乎未检测到细胞毒性活性。总体而言，我们的数据表明黑色素瘤细胞中HLA - A2抗原表达的选择性下调可能是肿瘤细胞逃避免疫识别的机制之一。
