MIP-1α and MIP-1β induce CCR5-mediated chemotaxis of HCs in vitro but are not detected in the cord blood. MIP-1α and MIP-1β ligands for the CCR5 receptor play an important role in modulating immune responses. To examine CCR5-induced migration (A), HCs and MDMs were pretreated with or without human CCR5 monoclonal antibody (5 μg/ml), placed in Transwell inserts, and stimulated with MIP-1α (10 ng/ml) and MIP-1β (10 ng/ml). Results are expressed as chemotactic index (CI). CI is calculated by dividing the mean number of cells migrating toward chemoattractants by that toward control medium. Data shown are means ± SE of three independent experiments from different donors (* p < 0.05). To detect the presence of HCs in cord blood (B), cells were stained with PE-DC-SIGN, PE-Cy7-CD4, PerCP-CCR5, PE-Cy7-CXCR4, PE-HLA-ABC, APC-HLA-DR, APC-CD11b, PE-CD11c, PE-83, APC-CD86, and FITC-CD14. Quadrants were set according to uninfected control staining. Cells were gated on CD14+ cells. Flow cytometry pictures show a representative of 5 different donors.