白细胞新单克隆抗体ZCH-2Ba的表达谱分析及其意义

ZCH-288a（IgG2a）是作者研究室最近采用髓细胞性白血病细胞系KG1a作为免疫原自行研制的鼠抗人造血细胞分化抗原的单克隆抗体，已提交第8届国际人类白细胞分化抗原协作组会议（HLDA8）鉴定。根据HL-DAB总部反馈信息表明，该抗体识剐的抗原性质不明，后者属国际上尚未认识的血细胞膜新的分化抗原。本研究旨在分析ZCH-288a单克隆抗体与正常人外周血细胞成分、骨髓及G-CSF动员的外周血CD34^＋造血干／祖细胞和血液肿瘤细胞系的反应规律及其意义。采用多参数流式细胞术分析288a抗体与正常及恶性肿瘤细胞表面的反应性，每种细胞成分重复实验3次，以阳性细胞数I〉20％为阳性。结果表明：288a抗原在外周血B细胞上表达（3／3例，平均阳性细胞数为26．29％），而在T淋巴细胞和NK细胞上不表达（0／3例）；在粒细胞和单核细胞上阳性表达均为2／3例，平均阳性细胞数分别是23．72％和59．84％；在DC细胞、红细胞和血小板上均不表达（0／3例）。288a抗原在骨髓CD34^＋细胞上的阳性表达是3／3例，平均阳性细胞数39．33％，而在G-CSF动员的外周血CD34^＋细胞上的阳性表达仅1／3例，平均阳性细胞数为1．25％。288a抗原在B系细胞系Raji、SMS-SB、Nalm-6和Nall-1上的平均阳性细胞数分别为98．78％、98．61％、94．93％和5．68％；在T系细胞系Molt-3上的平均阳性细胞数为31．40％，而在Molt-4、JM和CCRF-CEM细胞上不表达；在髓系细胞系U937、Meg-01、HL-60、K562、KG1a和HEL92．1．7上的平均阳性细胞数分别为67．78％、33．40％、29．70％、28．19％、16．23％和8．02％；在神经母细胞瘤细胞系SK-N-SH、KCNR、BE、LAN-1和SK-N-As细胞以及结肠癌细胞系HR8348细胞上均不表达，而在羊膜细胞系FL细胞上呈一定的阳性表达，平均阳性细胞数为45．03％。结论：在正常外周血，288a抗体主要与B淋巴细胞和单核巨噬细胞反应，在骨髓和外周血CD34^＋造血干／祖细胞中也有不同程度的反应性；在细胞系上，288a抗体主要与B系细胞系、单核巨噬细胞系及上皮性肿瘤细胞系反应，提示该抗体有可能用于上述肿瘤的免疫学诊断与治疗。

Reactivity of a Novel Monoclonal Antibody ZCH-2BSa on Normal Hematopoietic Cells and Malignant Cell Lines and Its Significance

ZCH-2B8a (IgG2a) is a novel monoclonal antibody (McAb) generated in laboratory of Children Hospital of Medical College, Zhejiang University recently using human myeloblastic leukemia cell line KG1a as immunogen. This antibody has been submitted to the 8th International Workshop and Conference on Human Leukocyte Differentiation Antigens (HLDA8) and the results showed that the antibody recognized an unknown molecule on the surface of some blood cells. The aim of this study was to investigate the reactivity of this antibody on normal blood cells and malignant cell lines and to explore its possible application in clinical practice. The multi-parameter flow cytometry was used to analyze the expression pattern of 2B8a antigen in triplicate on normal blood components including T cells, B cells, natural killers (NK), neutrophils, monocytes, dendritic cells (DC), red blood cells (RBC), platelets (Plt), hematopoietic stem/progenitor cells derived from either bone marrow or G-CSF mobilized peripheral blood CD34(+) cells and malignant cell lines including 14 hematopoietic, 5 neuroblastoma, 1 colon cancer and 1 amniotic epithelium cell lines. The amount of positive cells > or = 20% was considered as positivity. The results showed that 2B8a antibody reacted to 3/3 specimens of blood B cells with a positive rate of 26.29% and 2/3 specimens of monocytes with an average positive rate of 59.84%. 2B8a was weakly reactive to neutrophils (23.72%) and negative for T cells, NK, DC, RBC and Plt. The antibody reacted to all 3 marrow CD34(+) cells with an average positive rate of 39.33% while it was negative for G-CSF-mobilized CD34(+) peripheral blood stem/progenitor cells (PBSC, 1.25%). Cell line analysis showed that the antibody notably reacted to three out of 4 cell lines (Raji, SMS-SB, Nalm-6 and Nall-1) with the positive rates of 98.78%, 98.61%, 94.93% respectively and weakly to one of them with 5.68% in B lineage cell lines and monoblastic cell line (U937, 67.78%) while it was only weakly positive or negative for other myeloid leukemia cell lines including Meg01 (33.40%), HL-60 (29.70%), K562 (28.19%), KG1a (16.23%) and HEL92.1.7 (8.02%). Among 4 T lineage leukemia, 5 neuroblastoma and 1 colon cancer cell lines tested, only Molt-3 was found weakly positive (31.40%) for 2B8a, while the remaining 3 T cell lines (Molt4, JM and CCRF-CEM), 5 neuroblastoma cell lines (LA-N1, KCNR, BE, SK-N-SH, SK-N-AS) and the colon cancer cell line (HR8348) tested were negative. An amniotic epithelium cell line (FL) was showed positive for the antibody (45.03%). It is concluded that 2B8a antibody primarily reacts to B lineage and monocytic lineage cells which may bear the diagnostic and therapeutic applications among different types of hematopoietic malignancies.