Effects of clinical isolates of Streptococcus pneumoniae on THP-1 human monocytic cells.

Twenty-three clinical Streptococcus pneumoniae (SP) strains were isolated from blood and sputum specimens from the Second Affiliated Hospital of Wenzhou Medical College in 2009. These strains and the ATCC 49619 standard strain were cultured and suspended in normal saline (at a turbidity of 1.0 McFarland). The production of interleukin (IL)-8, intracellular adhesion molecule-1 (ICAM-1) and IL-10 in THP-1 cells following stimulation with the SP suspension was analyzed by an enzyme-linked immunosorbent assay. The concentrations of IL-8, ICAM-1 and IL-10 from the THP-1 monocytes were greater than those of the blank control following stimulation with the SP suspension. No significant difference was identified in the levels of IL-8, ICAM-1 and IL-10 secretion between THP-1 monocytes stimulated by blood-borne SP (bb-SP) and sputum-borne SP (sb-SP).