Infant mice do not form a gradient of CCL2 expression during colonization.

<p>(A) Adult (42d old) and infant (7d old) mice were inoculated with PBS (mock) or pneumococci. At 3d post-inoculation, nasal lavages were obtained with RLT lysis buffer, and RNA was isolated and reverse transcribed to cDNA. qRT-PCR was performed to measure relative expression of <i>Ccl2</i>. (B) Serum was obtained from adult and infant mice, and ELISA used to measure CCL2 levels. (C-D) Peritoneal macrophages from adult and infant mice were lysed with RLT buffer and RNA isolated. qRT-PCR was used to measure relative expression of <i>Ccl2</i> (C) and <i>Ccr2</i> (D). In (C), cultured macrophages were incubated overnight with PBS (Mock) or heat-killed bacterial lysates (Stim) prior to lysis. (E-H) Uncolonized adult and infant mice were sacrificed, and nasal lavages obtained with RLT lysis buffer. RNA was isolated and reverse-transcribed into cDNA. qRT-PCR was used to measure relative expression of <i>Ccl7</i>, (E) <i>Il6</i>, (F) <i>Cxcl1</i>, (G) and <i>Cxcl2</i> (H). Data are represented as mean +/- SEM. n.s., not significant. * = p < 0.05, ** = p < 0.01, *** = p < 0.001.