单核细胞在含内毒素的微环境中分化时表型与功能的改变

Phenotypic and functional characteristics of macrophages differentiated in endotoxin-containing environment

目的 观察单核细胞在含内毒素 (LPS)的微环境中分化成巨噬细胞时 ,其表型与功能的变化。方法 以含LPS的介质体外培养纯化的正常人循环单核细胞 ,在其分化为巨噬细胞的不同阶段观察形态、超微结构、细胞表面HLA DR、补体 3受体 (C3R)和甘露糖受体 (MR)的表达以及细胞分泌超氧离子 (O-2 )、白细胞介素 1β(IL 1β)和肿瘤坏死因子α(TNF α)的变化。结果 与在自身血清中分化的巨噬细胞相比 ,(1)在含LPS介质中发育的巨噬细胞体积较小 ,但具有正常巨噬细胞的超微结构特征 ;(2 )在分化早期 (第 1天 ) ,其HLA DR的表达明显上调 ,而在成熟阶段 (第 5天 )表达下调。LPS对C3R和MR的表达无明显作用 ;(3)在含LPS介质中分化的巨噬细胞 ,其在佛波醇肉豆蔻乙酸盐刺激下生成O-2 的能力得以保持。自发分泌IL 1β和TNF α的水平明显高于在血清中分化的巨噬细胞。结论 在含LPS微环境中分化的巨噬细胞具有与正常单核细胞衍生的巨噬细胞所不同的功能特征 ,表现为MHCⅡ类抗原的表达降低 ,促炎症介质的生成增加。

Objective To further understand the macrophage heterogeneity in the infection and inflammation, we characterized the phenotype and functional behavior of human monocytes differentiated in endotoxin (LPS)-containing cultures. Methods Purified human peripheral monocytes were cultured with medium containing 1μg/ml of LPS. Their ultrastructure, expression of membrane antigens and production of superoxide and the cytokines were determined at various stages of their differentiation. Results Monocytes cultured with LPS underwent substantial changes in morphology similar to that observed when monocytes differentiated into macrophages. However, they exhibited different functional behavior from macrophages matured in autologous serum. The expression of HLA-DR was up-regulated in these cells at day 1 of culture, and down-regulated at day 5. Superoxide production in response to phorbol myristic acetate was maintained in LPS cultured macrophages, but declined with time in cells cultured with serum. Spontaneous secretion of tumor necrosis factor-α and interleukin-1β was higher in macrophages developed in LPS compared with those matured in serum. Conclusion Human monocytes maintained in LPS-containing cultures exhibit differentiation-associated activation phenotype, which differs from that of normal monocyte-derived macrophages, characterized by decreased MHC classⅡ antigen expression and higher capacity for generation of proinflammatory mediators.