摘要目的:探讨弥漫性大B细胞淋巴瘤（DLBCL）中MYD88 L265P突变对肿瘤细胞及肿瘤微环境中PD-L1表达的影响，为患者进行免疫治疗提供理论依据。方法:采用多重连接探针扩增技术检测2008年8月至2010年5月间经中国医学科学院肿瘤医院病理诊断明确的72例初治性DLBCL石蜡包埋样本中MYD88 L265P突变的发生频率。采用Ventana全自动免疫组织化学平台对所有样本进行PD-L1（22C3）及PD-L1（SP142）检测，分别观察肿瘤细胞及肿瘤微环境中PD-L1的表达情况，分析MYD88 L265P突变与DLBCL肿瘤细胞及肿瘤微环境PD-L1表达的关系。结果:72例DLBCL组织标本中，MYD88 L265P突变15例（20.8%）。剔除9例伴有JAK2扩增的病例，将63例DLBCL分成MYD88 L265P突变型组14例，MYD88 L265P野生型组49例。免疫组织化学结果显示，14例MYD88 L265P突变组中，7/14肿瘤细胞PD-L1（22C3）表达阳性，4/14肿瘤微环境PD-L1（SP142）表达阳性。在49例MYD88 L265P野生型组中，9例（18.4%）肿瘤细胞PD-L1（22C3）表达阳性，38例（77.6%）肿瘤微环境PD-L1（SP142）表达阳性。并且在16例肿瘤细胞PD-L1（22C3）表达阳性的DLBCL中，7例伴有MYD88 L265P突变者中仅2例肿瘤微环境PD-L1（SP142）阳性；9例MYD88 L265P野生型者肿瘤微环境PD-L1（SP142）表达均阳性。统计学分析显示，MYD88 L265P突变型组肿瘤细胞PD-L1（22C3）的阳性率明显高于野生型组（ P=0.017）；MYD88 L265P突变型组肿瘤微环境PD-L1（SP142）的阳性率明显低于野生型组（ P=0.001）。 结论:MYD88 L265P突变可能在调控DLBCL肿瘤细胞及肿瘤微环境PD-L1的表达中发挥了一定作用，进一步的研究将为MYD88 L265P突变DLBCL患者进行免疫治疗提供理论依据。

abstractsObjective:To study the effect of MYD88 L265P mutation on the expression of PD-L1 in tumor cells and tumor microenvironment in diffuse large B-cell lymphoma (DLBCL), and to provide theoretical basis for immunotherapy for patients.Methods:Multiplex ligation-dependent probe amplification (MLPA) was used to detect the frequency of MYD88 L265P mutation in 72 cases of DLBCL diagnosed by pathologists in Cancer Hospital of Chinese Academy of Medical Sciences from August 2008 to May 2010. Expression of PD-L1 in tumor cells and tumor microenvironment in all samples was evaluated using PD-L1 (22C3) and PD-L1 (SP142) with Ventana automatic immunohistochemical (IHC) platform. The relationship between MYD88 L265P mutation and the expression of PD-L1 in DLBCL tumor cells and tumor microenvironment was assessed.Results:Of the 72 cases of DLBCL, MYD88 L265P mutation was detected in 15 (20.8%) cases. Nine cases with JAK2 amplification were excluded, and the remaining 63 cases of DLBCL were divided into MYD88 L265P mutant group ( n=14) and MYD88 L265P wild-type group ( n=49). IHC results showed that among the 14 cases of MYD88 L265P mutant groups, PD-L1 (22C3) was positive in 7 cases (7/14) of tumor cells and PD-L1 (SP142) was positive in 4 cases (4/14) of tumor microenvironment. Among the 49 cases of MYD88 L265P wild-type group, 9 cases (18.4%) were positive for PD-L1 (22C3) in tumor cells, and 38 cases (77.6%) were positive for PD-L1(SP142) in tumor microenvironment. In addition, among the 16 cases with PD-L1(22C3) expression in tumor cells, only 2 of the 7 cases with MYD88 L265P mutation were positive for PD-L1 (SP142) in tumor microenvironment. All 9 cases with wild-type MYD88 L265P were positive for PD-L1 (SP142) in tumor microenvironment. Statistical analysis showed that the expression level of PD-L1 (22C3) in tumor cells in the MYD88 L265P mutant group was significantly higher than that in the MYD88 L265P wild-type group ( P=0.017). The expression level of PD-L1 (SP142) in tumor microenvironment in the MYD88 L265P mutant group was significantly lower than that in the MYD88 L265P wild-type group ( P=0.001). Conclusions:MYD88 L265P mutation may play an important role in the regulation of PD-L1 expression in DLBCL tumor cells and tumor microenvironment. Further studies will provide a theoretical basis for immunotherapy of DLBCL patients with MYD88 L265P mutation.