FIG 8.

Bacterial uptake by osteoblasts is increased after treatment of cells with trypsin or supernatant of lysed neutrophils. Cells as indicated were treated with either 1 μg/ml trypsin for 30 min (A) or with 10% supernatant of neutrophil lysate (B), destroyed by ultrasound, overnight. Afterwards cells were washed and infected with S. aureus 6850. One hour post infection, extracellular staphylococci were removed by lysostaphin treatment. Subsequently, the host cells were detached and the number of host cells was determined. Host cells were lysed and the number of viable intracellular bacteria was assessed by plate counting. Data are means ± SD from 3 independent experiments. Numbers of intracellular bacteria in control cells were set to 100%; *, P < 0.05; **, P ≤ 0.01, unpaired t test.