Figure 4

Recombinant IL-8 stimulates SCLC cell proliferation through CXCR1. (A) The SCLC cell lines H69, Lu165, H345 and GLC-19 were treated with rIL-8 at concentrations of 0.01, 0.1, 1 and 10 ng ml⁻¹ for 48 h. Cell proliferation was measured by MTT assay. Each point is the mean±s.e. of three determinations from two independent experiments. ^*P<0.05. (B) Detection of PCNA intensity by flow cytometry after H69 cells was treated with rIL-8 (1 ng ml⁻¹) for 48 h. (C) Analysis of DNA content by flow cytometry after H69 cells was treated with rIL-8 (1 ng ml⁻¹). (D) Small cell lung cancer cells were treated with rIL-8 plus anti-CXCR1 or anti-CXCR2 antibody for 48 h. The concentration of rIL-8 for each cell line was chosen for maximal stimulation: 10 ng ml⁻¹ for Lu165 and 1 ng ml⁻¹ for others. The final concentration of anti-CXCR1 or anti-CXCR2 was 10 μg ml⁻¹. Each bar is the mean±s.e. of three independent determinations of two experiments. ^*P<0.05 for inhibition of rIL-8-induced proliferation by anti-CXCR1 antibody.