Falini B, Flenghi L, Fagioli M, Lo Coco F, Cordone I, Diverio D, Pasqualucci L, Biondi A, Riganelli D, Orleth A, Liso A, Martelli M F, Pelicci P G, Pileri S
Institutes of Hematology and Internal Medicine, University of Perugia, Perugia, Italy.
Blood. 1997 Nov 15;90(10):4046-53.
Acute promyelocytic leukemia (APL) is characterized by a reciprocal 15; 17 chromosomal translocation, which fuses the promyelocytic leukemia (PML) and retinoic acid receptor alpha (RARalpha) genes, leading to the expression of the PML/RARalpha fusion oncoprotein. Immunocytochemical labeling of the wild-type PML protein with the PG-M3 monoclonal antibody (MoAb) directed against the amino terminal portion of the human PML gene product, produces a characteristic nuclear speckled pattern that is due to localization of the protein into discrete dots (5 to 20 per nucleus), named PML nuclear bodies. The architecture of PML nuclear bodies appears to be disrupted in APL cells that bear the t(15; 17), thus resulting in a change of the nuclear staining pattern from speckled (wild-type PML protein) to microgranular (PML-RARalpha fusion protein). To assess whether the PG-M3 MoAb could assist in the diagnosis of APL (M3), bone marrow and/or peripheral blood samples from 100 cases of acute nonlymphoid leukemias of different subtypes were blindly immunostained with the PG-M3 MoAb, using the immunoalkaline phosphatase (APAAP) or immunofluorescence technique as detection system. Notably, the abnormal (micropunctate) pattern of the PML/RARalpha fusion protein (usually >/=50 small granules/per nucleus) was observed in APL (M3) samples, but not in other types of acute nonlymphoid leukemias. Immunocytochemical labeling with PG-M3 was particularly useful in the diagnosis of microgranular variant of APL (M3V) (three cases misdiagnosed as M4 and M5), and also to exclude a morphologic misdiagnosis of APL (six of 78 cases). In all cases investigated, immunocytochemical results were in agreement with those of reverse transcription-polymerase chain reaction (RT-PCR) for PML/RARalpha. Because the epitope identified by PG-M3 is located in the aminoterminal portion of PML (AA 37 to 51), the antibody was suitable for recognizing APL cases characterized by breakpoint occurring at different sites of PML (bcr 1, bcr 2 and bcr 3). In conclusion, immunocytochemical labeling with PG-M3 represents a rapid, sensitive, and highly-specific test for the diagnosis of APL that bears the t(15; 17). This should allow an easy and correct diagnosis of this subtype of acute leukemia to any laboratory provided with a minimal equipment for immunocytochemistry work.
急性早幼粒细胞白血病（APL）的特征是15号与17号染色体相互易位，该易位使早幼粒细胞白血病（PML）基因与维甲酸受体α（RARα）基因融合，导致PML/RARα融合癌蛋白的表达。用针对人PML基因产物氨基末端部分的PG-M3单克隆抗体（MoAb）对野生型PML蛋白进行免疫细胞化学标记，会产生一种特征性的核斑点模式，这是由于该蛋白定位于离散的点（每个核5至20个），即所谓的PML核体。在携带t(15; 17)的APL细胞中，PML核体的结构似乎被破坏，从而导致核染色模式从斑点状（野生型PML蛋白）变为微粒状（PML-RARα融合蛋白）。为了评估PG-M3 MoAb是否有助于APL（M3型）的诊断，使用免疫碱性磷酸酶（APAAP）或免疫荧光技术作为检测系统，用PG-M3 MoAb对100例不同亚型的急性非淋巴细胞白血病患者的骨髓和/或外周血样本进行盲法免疫染色。值得注意的是，在APL（M3型）样本中观察到PML/RARα融合蛋白的异常（微点状）模式（通常每个核≥50个小颗粒），而在其他类型的急性非淋巴细胞白血病中未观察到。用PG-M3进行免疫细胞化学标记在APL微颗粒变异型（M3V）的诊断中特别有用（3例曾被误诊为M4和M5型），也有助于排除APL的形态学误诊（78例中有6例）。在所有研究病例中，免疫细胞化学结果与PML/RARα的逆转录聚合酶链反应（RT-PCR）结果一致。由于PG-M3识别的表位位于PML的氨基末端部分（氨基酸37至51），该抗体适用于识别以PML不同位点发生断裂点（bcr 1、bcr 2和bcr 3）为特征的APL病例。总之，用PG-M3进行免疫细胞化学标记是一种快速、灵敏且高度特异的诊断携带t(15; 17)的APL的检测方法。这使得任何配备了最基本免疫细胞化学工作设备的实验室都能轻松且正确地诊断这种急性白血病亚型。
