Effect of IFN-γ on chemotaxis to MIP-1 and MIP-1β. Monocytes from adult blood (n = 2) and cord blood (n = 1) were incubated for 12 hours with IFN-γ (10, 100, 500, and 1,000 U/mL). Migration of untreated and IFN-γ–treated monocytes to control medium, MIP-1, and MIP-1β (10 ng/mL) was studied as described in Materials and Methods. Results (number of cells migrated per high power field after subtraction of spontaneous migration; mean ± SEM; 3 replicates) from 1 representative donor are shown (*P < .05, IFN-γ v untreated).