Hart D N, Starling G C, Calder V L, Fernando N S
Haematology Department, Christchurch Hospital, New Zealand.
Immunology. 1993 Aug;79(4):616-20.
Activation of a primary T-lymphocyte response requires additional signals apart from interaction of the T-cell receptor (TcR)/CD3 complex with major histocompatibility complex (MHC) antigens on the antigen-presenting cell. The CD28 antigen on T lymphocytes provides an important co-stimulatory signal to T lymphocytes and we therefore searched for the presence of its ligand, the B7/BB-1 antigen, on blood and tonsil dendritic cells (DC). Blood DC, prepared from peripheral blood mononuclear cells with a minimal period of in vitro culture, did not stain with the monoclonal antibody BB-1 using flow cytometry analysis. In contrast, tonsil DC stained weakly for B7/BB-1 compared to positive control cell lines. Polymerase chain reaction (PCR) was used to amplify a 605 base pair (bp) fragment from human B7/BB-1 mRNA and demonstrated significant amounts of B7/BB-1 mRNA in tonsil DC but no specific product was obtained from blood DC, confirming the surface-staining results. Weak expression of B7/BB-1 antigen was detected by immunofluorescence analysis following culture of blood DC with either interferon-gamma (IFN-gamma) or granulocyte-macrophage colony-stimulating factor (GM-CSF). These data support the concept that blood DC give rise to tissue and/or lymphoid DC, which acquire co-stimulatory ligands as a result of activation and/or differentiation.
初始T淋巴细胞反应的激活除了需要T细胞受体（TcR）/CD3复合物与抗原呈递细胞上的主要组织相容性复合体（MHC）抗原相互作用外，还需要其他信号。T淋巴细胞上的CD28抗原为T淋巴细胞提供重要的共刺激信号，因此我们研究了血液和扁桃体树突状细胞（DC）上其配体B7/BB-1抗原的存在情况。通过对外周血单核细胞进行最短时间的体外培养制备的血液DC，使用流式细胞术分析时不能被单克隆抗体BB-1染色。相比之下，与阳性对照细胞系相比，扁桃体DC对B7/BB-1的染色较弱。聚合酶链反应（PCR）用于从人B7/BB-1 mRNA中扩增出一个605碱基对（bp）的片段，结果显示扁桃体DC中有大量的B7/BB-1 mRNA，但血液DC中未获得特异性产物，这证实了表面染色结果。用干扰素-γ（IFN-γ）或粒细胞-巨噬细胞集落刺激因子（GM-CSF）培养血液DC后，通过免疫荧光分析检测到B7/BB-1抗原的弱表达。这些数据支持这样一种概念，即血液DC可分化为组织和/或淋巴DC，后者在激活和/或分化过程中获得共刺激配体。
