Alveolar macrophages express less CCL2R/CCR2 RNA than peripheral blood monocytes. Using 10 μg of total RNA extracted from freshly isolated peripheral blood monocytes or alveolar macrophages, single stranded cDNA was synthesized and subjected to microarray analysis (n = 2) or 30 cycles of multiplex PCR using primers for CCR2 and GAPDH. Affymetrix microarray analysis indicated that a) alveolar macrophages express less CCL2RB (HG-U95Av2 39937 at, Accession No. U03905) than peripheral blood monocytes (*p < 0.05). b) Reverse transcriptase PCR for CCR2 confirmed these results. The bands shown in (b) are representative of 3 independent experiments from matched donors different than those used in (a), and the corresponding graph shows the ratio of CCR2 to GAPDH control band intensity by densitometry, averaged over the three donors ± SEM (*p < 0.05 for CCR2 expression in alveolar macrophages compared to monocytes from the same donors).