Fig 2.

Mitogenic activity induced by overnight bacterial culture supernatants. Peripheral blood mononuclear cells from healthy donors were stimulated with bacterial supernatants prepared from invasive isolates collected at the north site (A) and south site (B). Proliferative responses were determined after 72 h of culture by measurement of [³H]thymidine uptake. The data are shown as mean counts per minute ± SD of triplicate experiments for unstimulated cells (unst.) and cells stimulated with supernatants of all invasive isolates (indicated by patient identifier) or phytohemagglutinin (PHA) as a positive control.