人脐血T、B淋巴细胞和NK细胞的免疫学表达特性

目的 探讨人脐血T、B淋巴细胞和NK细胞，以及T／NK细胞杀伤性抑制性受体（KIR）表达的免疫学特性及其意义。方法 应用流式细胞仪检测26例正常新生儿脐血的T、B淋巴细胞和NK细胞抗原标记，包括CD45RA、CD45RO、CD69、CD25、CD40L、CD40、CD10、CD20和CD16等抗原的表达，以及脐血T／NK细胞上KIR分子（CD158a和CD158b抗原）的表达，并与正常儿童外周血比较。结果 脐血T淋巴细胞中CD45RA^ 细胞表达高于外周血（P＜0．01），CD45RO^ 则明显低于外周血（P＜0．01）；脐血T细胞CD69表达极低；CD25在CD8^ 细胞亚群中几乎不表达；CD40L在脐血T细胞中表达低于外周血（P＜0．05）。脐血B淋巴细胞中不成熟亚群CD10^ ／CD19^ 比例增高，成熟B细胞表型CD19、CD20、CD40等抗原均明显高于正常外周血（P＜0．01）。脐血中T淋巴细胞和NK细胞均存在KIR分子表达；脐血和外周血中T淋巴细胞CD158分子表达低于NK细胞（P＜0．01），脐血T淋巴细胞亚群中CD158分子表达低于正常外周血；CD158几乎不表达于CD4^ T细胞，主要表达于CD8^ T细胞，且以CD158a^ 为主；脐血中NK细胞CD158分子表达高于T淋巴细胞（P＜0．05），但明显低于外周血NK细胞KIR的表达（P＜0．01）。结论 脐血T淋巴细胞包括原始和早期T细胞以及T细胞受体表达障碍，导致脐血T淋巴细胞免疫功能不成熟，可能是脐血移植（UCBT）后移植物抗宿主病（GVHD）发生率低和程度轻的重要原因之一。脐血B淋巴细胞免疫应答障碍可能缘于T淋巴细胞表型或功能的障碍。脐血T／NK细胞KIR的表达特性提示，KIR可能与UCBT中GVHD和移植物抗白血病（GVL）效应有关。

Immunophenotypic characteristics of the lymphocytes and natural killer cells in human umbilical cord blood

Objective With the development of umbilical cord blood transplantation (UCBT) in children hematological diseases, the biological features of the immune cells in the umbilical cord blood (UCB) were focused on, especially the immunophenotypic characteristics of effective cells which play an important role in graft versus host disease (GVHD) and graft versus leukemia (GVL) action in UCB The T and B lymphocyte subsets and natural killer (NK) cells of UCB were related to GVHD and GVL after UCBT It was known that killer inhibitory receptors (KIR) expressed on NK cells, but recently KIR was found to express on the CD + 8T lymphocytes also, and its action was unclear in GVHD and GVL This study aimed to explore the immunophenotypic characteristics and significances of the lymphocytes and NK cells and, the KIR expression on T or NK cells in human UCB Methods The antigen markers of T and B lymphocytes and NK cells, including CD 45 RA, CD 45 RO, CD 25 , CD 69 , CD 40 L, CD 40 , CD 10 , CD 20 , CD 16 and KIR (CD 158a and CD 158b ) expressed on the surfaces of peripheral blood T lymphocytes or NK cells, as well as expressed on T/NK cells of UCB were analyzed by flow cytometry (B D company, American) The direct fluorescent method was used There were 26 UCB samples from normal neonates and 22 peripheral blood (PB) samples from normal children The t test for the completely random designed experiment was performed between the mean values of different groups Results The expression of CD 45 RA +T cells in UCB was higher markedly than that in PB, and the expression of CD 45 RO +T cells in UCB was lower than that in PB The expression of CD 69 was too low to detect in UCB CD 25 almost unexpressed on CD + 8T cells in UCB The expression of CD 40 L + T cells in UCB was lower than that in PB The expressions of the maturity B lymphocyte subsets including CD 20 , CD 40 , CD 23 and CD 19 in UCB were higher than those in PB ( P <0 01) An increased percentage of the immature B lymphocyte (CD 10 ) was observed in UCB It was similar to PB that in UCB the expression of KIR on T lymphocytes was lower than that on NK cells The expression of KIR on the subsets of T lymphocytes in UCB was lower than that in PB ( P <0 01) CD 158 , especially CD + 158a , almost did not express on CD + 4 T lymphocytes, and mainly expressed on CD + 8T lymphocytes CD 158 expression on NK cells in UCB was lower than that in PB ( P <0 01) The expression of CD 158 on NK cells in UCB was higher than that on T lymphocytes ( P <0 01), but significantly lower than that on NK cells in PB ( P <0 01) Conclusion The expressions of T lymphocytes in UCB including naive T cells, early T cells and T cell receptor showed that the T cell immunity functions of UCB were immature, which provide the insight into the low incidence of the graft versus host disease The immature immunity of B cells in UCB may result from the immaturity of T cells The characteristics of KIR on T/NK cells in UCB may be related to the incidence of GVHD and GVL action.