Azithromycin (CP 62993) is an antibiotic by inhibiting protein synthesis, used for the treatment of bacterial infections.

Azithromycin 能将囊性纤维化（CF）细胞中的IL-8 mRNA和蛋白表达降低约40%，使其达到非CF细胞的水平。Azithromycin 导致NF-kappaB和AP-1 DNA结合能力分别降低50%和70%，从而接近非CF细胞的水平。Azithromycin 显著增强了树突细胞（DCs）上共刺激分子CD80的强度，但不影响CD86和CD40。Azithromycin 显著提高了IL-10的产生，而Clarithromycin （CAM）显著抑制了DCs产生IL-6。当与事先处理过LPS和这些大环内酯的DCs共培养时，Azithromycin 显著增加了IL-10的产量，而CAM显著减少了IL-2的产量。Azithromycin 选择性抑制了J774小鼠巨噬细胞中辣根过氧化物酶和露西黄的液相内吞作用。Azithromycin 延缓受体结合转铁蛋白和过氧化物酶-抗过氧化物酶免疫复合物进入细胞表面的内吞小窝和囊泡的封存。Azithromycin 通过延迟内化的转铁蛋白受体进入循环途径的可达性而下调细胞表面转铁蛋白受体，但不影响Fcγ受体，不延缓随后的排出，导致表面池向细胞内池的重分布。Azithromycin 插入DOPC脂质双层，从而降低其凝聚力并促进DPPC融合进DOPC流动基质。

THP-1 cells (106 cells in 1 mL RPMI medium, without antibiotics, growth factors or serum) are seeded in each well of 24-well plates and allowed to settle for 1 hour. Next, 50 μL of the test compound is added followed by 50 μL of LPS (final concentration of 10 μg/mL). After 24h (37°C and 5% CO2) the supernatants and cell pellets are collected (1200 rpm, 5 min). THP-1 cell viability is tested using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). MTT is dissolved at 2 mg/mL in PBS and aliquots are stored at -20°C. The MTT assay is performed according to the suppliers instructions. Absorbance of MTT converted into formazan is measured at a wavelength of 570 nm with background subtraction at 630 nm.