Streptococcus pneumoniae induces expression of the gene encoding microRNA-146a (miRNA-146a) in different immune cells. Primary human blood-derived macrophages (BDMs; A and B), THP-1 cells (C), or monocytes (D) were left untreated or infected with S. pneumoniae serotype 2 strain D39 (multiplicity of infection, 0.1) for 6 hours (A and B) or 20 hours (A, B, C, and D), respectively. RNA was isolated, and MIR146A expression was analyzed by quantitative reverse transcription–polymerase chain reaction (A, C, and D). B, Interleukin 8 (IL-8) secretion by BDMs was determined by enzyme-linked immunosorbent assay. Data are shown as mean ± standard error of the mean of 4 (A), 3 (B and C), or 2 (D) independent experiments performed in duplicates (C) or triplicates (D). Statistical analysis was performed as described in “Methods” section. *P < .05 and **P < .01. Abbreviation: THP-1, human monocytic leukemia cell line.