FIG. 4.

Cytokine mRNA production of HeLa cells after Y. enterocolitica pYV⁻ infection or exposure to IL-1 or IL-8. Cells were treated with various concentrations of recombinant human IL-1α or IL-8 for 1 h. Then the cells were washed and incubated with medium for another 2 h, when total RNA was extracted for RT-PCR analysis (see Materials and Methods). Data shown are from a representative experiment with duplicate samples. Comparable results were obtained in additional experiments.