FIG. 1.

Formation of CCR5 and C5aR1 heterodimers in human myeloid cells. (a) Flow cytometric analysis of C5aR1 and CCR5 coexpression in differentiated THP-1 cells and monocyte-derived macrophages (MDM). After differentiation, THP1 and MDM were stained for membrane expression with anti-CCR5 and anti-C5aR1 monoclonal antibodies (mAbs) or matched isotype control Abs. Quadrants were set up according to staining with isotype-matched control Abs. Percentages indicate the percentages of gated cells expressing each marker. (b) Frequencies of C5aR1⁺, CCR5⁺, or CCR5⁺C5aR1⁺ MDM. Data show values from 13 individual donors. Bars show the means ± SEM. (c) CCR5 was immunoprecipitated from THP-1 whole cell lysates followed by Western blot analysis of CCR5, C5aR1, CCR1, and G_αi2 expression. Left panel: two independent samples indicated as lanes A and B, respectively. Right panel: relative abundance of C5aR1, CCR1, and G_αi2 protein as determined by densitometric assessment of the band intensity. Data are the means ± SEM (in percent) of the Western blot signal obtained for each marker in comparison to the CCR5 signal obtained in the same sample (n = 4).