Gorelik E, Gunji Y, Herberman R B
Pittsburgh Cancer Institute, PA 15213.
J Immunol. 1988 Mar 15;140(6):2096-102.
The sensitivity of H-2b-high and H-2b-low variants of BL6 melanoma to the cytotoxic action of NK and lymphokine-activated killer cells was investigated. BL6 mouse melanoma cells lack detectable H-2Kb and had low levels of expression of H-2Db Ag. The BL6T2 variant cells, obtained after treatment of BL6 cells with mutagen N-methyl-N-nitro-N'-nitro-soguanidine, had relatively high levels of expression of class I H-2b Ag. Poly(I:C)-stimulated spleen cells of nude mice were highly cytotoxic for BL6T2, whereas H-2b-low BL6 cells were less sensitive to NK activity in an 18-h 51Cr-release assay. Similar results were obtained after 4-h incubation of radio-labeled tumor cells with IL-2-activated effector cells. In contrast, both lines were equally sensitive to lysis by purified granules derived from rat large granular lymphocytes (LGL) or by macrophages. By using various clones selected from BL6 or BL6T2 cells, it was found that BL6 or BL6T2 clones with low H-2b Ag expression were less sensitive to lysis by NK cells than H-2b-high clones. After IFN treatment of either BL6 or BL6T2, the target cells became more resistant to lysis by either NK cells or by purified LGL granules. IFN-treated BL6 cells had substantially increased expression of H-2b Ag and in this respect became similar to untreated BL6T2. However, IFN-treated BL6 cells were more resistant than BL6T2 cells to lysis by NK cells and LGL granules, suggesting that augmentation of H-2b Ag expression and NK resistance could be two independent IFN-induced effects. With a cold target inhibition assay, it was found that BL6T2 or its H-2 positive clones were highly competitive and inhibited the cytotoxic activity of NK and lymphokine-activated killer cells against radiolabeled YAC-1 and BL6T2, whereas BL6 cells or H-2-negative clones of BL6T2 and BL6 lines showed poor competitive ability. Thus, our data indicate that the NK resistance of H-2-low BL6 cells may be due to a paucity of NK recognizable determinants. N-Methyl-N-nitro-N'-nitroguanidine treatment of BL6 melanoma cells was associated with an increase in class I H-2b Ag expression and NK sensitivity, suggesting the involvement of class I MHC Ag in the sensitivity of tumor cells to NK cell-mediated cytotoxicity.
研究了BL6黑色素瘤的H-2b高表达和H-2b低表达变体对NK细胞和淋巴因子激活的杀伤细胞细胞毒作用的敏感性。BL6小鼠黑色素瘤细胞缺乏可检测到的H-2Kb，且H-2Db抗原表达水平较低。用诱变剂N-甲基-N-硝基-N'-亚硝基胍处理BL6细胞后获得的BL6T2变体细胞，其I类H-2b抗原表达水平相对较高。聚肌胞苷酸（Poly(I:C)）刺激的裸鼠脾细胞对BL6T2具有高度细胞毒性，而在18小时的51Cr释放试验中，H-2b低表达的BL6细胞对NK活性不太敏感。用IL-2激活的效应细胞与放射性标记的肿瘤细胞孵育4小时后，也得到了类似的结果。相反，这两种细胞系对来自大鼠大颗粒淋巴细胞（LGL）的纯化颗粒或巨噬细胞的裂解同样敏感。通过使用从BL6或BL6T2细胞中选出的各种克隆，发现H-2b抗原表达低的BL6或BL6T2克隆比H-2b高表达的克隆对NK细胞的裂解更不敏感。用IFN处理BL6或BL6T2后，靶细胞对NK细胞或纯化的LGL颗粒的裂解更具抗性。IFN处理的BL6细胞H-2b抗原表达大幅增加，在这方面变得与未处理的BL6T2相似。然而，IFN处理的BL6细胞比BL6T2细胞对NK细胞和LGL颗粒的裂解更具抗性，这表明H-2b抗原表达的增加和对NK的抗性可能是IFN诱导的两种独立效应。通过冷靶抑制试验发现，BL6T2或其H-2阳性克隆具有高度竞争性，并能抑制NK细胞和淋巴因子激活的杀伤细胞对放射性标记的YAC-1和BL6T2的细胞毒活性，而BL6细胞或BL6T2和BL6系的H-2阴性克隆竞争能力较差。因此，我们的数据表明，H-2低表达的BL6细胞对NK的抗性可能是由于缺乏NK可识别的决定簇。用N-甲基-N-硝基-N'-亚硝基胍处理BL6黑色素瘤细胞与I类H-2b抗原表达增加和对NK的敏感性增加有关，这表明I类MHC抗原参与了肿瘤细胞对NK细胞介导的细胞毒性的敏感性。
