MIP-1α/β released by PMNs is responsible for MΦ influx into cutaneous granulomas.
(A) Expression of the chemokines MIP-1α, MIP-1β, and MIP-2 by PMNs from early CGs (6 hours and 12 hours old) was found using the RNAse protection assay (PharMingen). One of 2 experiments with similar results is shown. Lane 1 shows the template set; lanes 2 and 3, PMN RNA; lane 4, control RNA provided by the manufacturer. (B) Production of MIP-1α and MIP-1β was determined in supernatants of 2 × 106 PMNs in fully supplemented media after 18 hours. Chemokine production was enhanced in TNFα-treated PMNs (n = 5). In panel C, groups of 3 C57BL/6 mice were depleted of PMNs using mAb 7/4 as shown in Figure 4D, and CGs were reconstituted locally twice daily with either vehicle alone or PMN supernatant (PMN-SPNT) or PMN-SPNT that was pretreated with anti–MIP-1α and anti–MIP-1β for 30 minutes. MΦ numbers were determined after 48 hours and expressed as means ± SEMs (106 cells/granuloma). *P < .05. Data are pooled from 6 mice per group from 2 independent experiments.
