Figure 1.

Relative number of intracellular bacteria in each living U937 cell. The cultured HLA-B27 or HLA-A2-transfected U937 cells were infected with complement-opsonized S. Enteritidis PT4 KS8822/88 and the incubation was continued at 37°C for 1, 4, 8 or 24 h after infection. At the indicated time points, the host cells were lysed and the number of bacteria per cell was counted and reported as colony forming units (CFU). For both cell lines, the number of intracellular bacteria at 1 h after infection was designated 1. The numbers of intracellular bacteria at the following indicated time points are shown as fold changes relative to the number at 1 h after infection. Values are mean ± standard deviation of duplicate samples from a representative experiment out of three with similar results. * P < 0.05 versus S. Enteritidis-infected HLA-A2 transfectants. Data were compared using Student's paired 2-tailed t-test.