FIG 6.

Role of type III secretion in abscess formation in a neutropenic mouse. C57BL/6J mice were injected in the peritoneum with IgG2a antibodies or anti-Ly6G antibodies to deplete the neutrophils. The mice were then infected in the subcutaneous space with P. aeruginosa strains PA99 or PA99null. (A, B) Abscess areas (A) and dermonecrotic areas (B) were measured daily following infection. (C) Mice were sacrificed at 24 h postinfection. Abscess tissues were harvested, homogenized, and plated for CFU enumeration. Data are means plus standard errors of the means. Statistics were calculated by a one-way ANOVA and Tukey's multiple-comparison test. *, P < 0.05, ***, P < 0.001; n.s., no significant difference. Four mice were used in the group treated with IgG2a and infected with PA99null; 5 mice per group were used for all other conditions. D.P.I., days postinfection.