Analysis of Immune Escape from NK cell in Melanoma

基于T细胞的黑素瘤免疫治疗的一个更大的关注是由于黑素瘤相关抗原和/或HLA I类的丢失而导致的免疫逃逸现象。首席研究员一直在分析黑素细胞中HLA I类下调的机制。HLA I类在黑素瘤病变中下调，导致黑素瘤病变中没有T细胞浸润。理论上，黑色素瘤细胞中HLA I类的缺失允许NK细胞浸润。然而，大多数黑色素瘤病变既没有T细胞浸润，也没有NK细胞浸润。这些数据表明黑色素瘤细胞可以逃避NK细胞的攻击。在本研究中，利用MHC I类链相关分子A和B （MICA和MICB）的单克隆抗体研究了黑色素瘤中NK细胞的免疫逃逸。MICA和MICB是新克隆的NK细胞激活受体NKG2D的配体。主要研究人员发现：1)MICA在培养的人黑色素瘤细胞系中的表达，16例人黑色素瘤细胞系中，elisa检测显示MICA阳性。2)MICA在黑素细胞瘤中的表达利用冷冻的黑素细胞痣、原发性和转移性黑色素瘤病变免疫组织化学方法研究了MICA在黑素细胞病变中的表达。MICA在黑色素细胞痣中不表达，但在黑色素瘤病变中表达。MICA分别在30%、60%和20%的径向生长期、垂直生长期和转移性病变中表达。3) MICB单克隆抗体的筛选，MICB单克隆抗体与福尔马林固定组织切片不发生反应。因此，我试图从10多种MICB抗体中寻找一种能与福尔马林固定组织切片发生反应的MICB单克隆抗体。我们能够选择一个抗体MICB，可以反应与福尔马林固定组织切片使用检索抗原的方法。这些数据将有助于分析黑色素瘤中NK细胞的免疫逃逸，我的实验室正在进行进一步的研究项目。少

One of the larger concernsin melanoma T cell based immunotherapy is the immune escape phenomenon resulting from loss of melanoma associated antigens and/or HLA class I. The head investigator has been analyzing the mechanisms of down regulation of HLA class I in melanocytic cells.HLA class I was down regulated in melanoma lesions, which results in no T cell infiltration in such lesions. Theoretically loss of HLA class I in melanoma cells allows NK cell infiltration. However, most of the melanoma lesions show neither T cell nor NK cell infiltration. These data suggest that melanoma cells can escape from NK cell attack.In the present study, analysis of immune escape from NK cell in melanoma was investigated using monoclonal antibodies to MHC class I chain-related molecule A and B (MICA and MICB), which are ligands for the newly cloned NK cell activating receptor NKG2D.The head investigator found the following points :1)Expression of MICA in culture human melanoma cell linesTen of 16 human … More melanoma cell lines were shown to be MICA positive by ELISA.2)Expression of MICA in melanocytic tumorsExpression of MICA in melanocytic lesions was investigated immunohistochemically using frozen melanocytic nevus, and primary and metastatic melanoma lesions. MICA was not expressed in melanocytic nevus, however it was expressed in melanoma lesions. MICA was expressed in 30%, 60%, and 20% of radial growth phase, vertical growth phase, and metastatic lesions, respectively.3)Selection of monoclonal antibody to MICB which can react with formalin-fixed tissue sectionThe monoclonal antibody to MICA did not react with formalin-fixed tissue sections. Therefore, I tried to find a monoclonal antibody to MICB which can react with formalin-fixed tissue section from more than 10 antibodies to MICB. We were able to select one antibody to MICB that could react with formalin-fixed tissue sections using the retrieval antigen method.These data will facilitate the analysis of immune escape from NK cell in melanoma and further research project is under going at my laboratory. Less