Neutrophil emigration in the skin, lungs, and peritoneum: different requirements for CD11/CD18 revealed by CD18-deficient mice

Abstract

To determine the role of CD11/CD18 complexes in neutrophil emigration, inflammation was induced in the skin, lungs, or peritoneum of mutant mice deficient in CD18 (CD18-/- mutants). Peripheral blood of CD18-/- mutants contained 11-fold more neutrophils than did blood of wild-type (WT) mice. During irritant dermatitis induced by topical application of croton oil, the number of emigrated neutrophils in histological sections of dermis was 98% less in CD18-/- mutants than in WT mice. During Streptococcus pneumoniae pneumonia, neutrophil emigration in CD18-/- mutants was not reduced. These data are consistent with expectations based on studies using blocking antibodies to inhibit CD11/CD18 complexes, and on observations of humans lacking CD11/CD18 complexes. The number of emigrated neutrophils in lung sections during Escherichia coli pneumonia, or in peritoneal lavage fluid after 4 h of S. pneumoniae peritonitis, was not reduced in CD18-/- mutants, but rather was greater than the WT values (240 +/- 30 and 220 +/- 30% WT, respectively). Also, there was no inhibition of neutrophil emigration during sterile peritonitis induced by intraperitoneal injection of thioglycollate (90 +/- 20% WT). These data contrast with expectations. Whereas CD11/CD18 complexes are essential to the dermal emigration of neutrophils during acute dermatitis, CD18-/- mutant mice demonstrate surprising alternative pathways for neutrophil emigration during pneumonia or peritonitis.

Figure 1

Expression of CD11a–CD18 and CD11b– CD18 by peripheral blood neutrophils from WT and CD18^−/− mutant mice. Blood was withdrawn from the inferior vena cava of mice after 6 h of croton oil dermatitis. Shown are representative linear-scale fluorescence histograms from WT (+/ +) or CD18-mutant (−/−) neutrophils labeled with monoclonal antibodies H129.19 against murine CD4 as a nonbinding control (A), M17/4 against murine CD11a (B), or M1/70 against murine CD11b (C).

Figure 2

Dermal neutrophil emigration in WT and CD18^−/− mice 6 h after topical application of 2% croton oil. Emigrated neutrophils were quantitated morphometrically and expressed as mean ± SEM standardized volume fractions for WT (closed bars) or CD18^−/− (open bars) mice. *Significant differences from WT; ^‡significant differences from control (untreated) ears (P <0.05).

Figure 3

Neutrophils in the alveolar septae of uninfected WT or CD18^−/− mice and 6 h after intratracheal instillation of E. coli or S. pneumoniae. Septal neutrophils were quantitated morphometrically and expressed as the mean ± SEM volume percent of septal tissue occupied by neutrophils for WT (closed bars) or CD18^−/− (open bars) mice. *Significant differences from WT; ^‡significant differences from uninfected mice (P <0.05).

Figure 4

Neutrophils in the alveolar air spaces of uninfected WT or CD18^−/− mice and 6 h after intratracheal instillation of E. coli or S. pneumoniae. Emigrated neutrophils were quantitated morphometrically and expressed as the mean ± SEM volume percent of alveolar air space occupied by neutrophils for WT (closed bars) or CD18^−/− (open bars) mice. *Significant differences from WT; ^‡significant differences from uninfected mice (P <0.05).

Figure 5

Peritoneal neutrophil emigration in WT and CD18^−/− mice 0, 4, or 24 h after intraperitoneal injection of S. pneumoniae. Emigrated neutrophils were quantitated in peritoneal lavage fluids and expressed as mean ± SEM neutrophils/lavage for WT (closed bars) or CD18^−/− (open bars) mice. *Significant differences from WT; ^‡significant differences from 0-h (uninfected) mice (P <0.05).

Figure 6

Peritoneal neutrophil emigration in WT and CD18^−/− mice 0, 4, or 24 h after intraperitoneal injection of thioglycollate. Emigrated neutrophils were quantitated in peritoneal lavage fluids and expressed as mean ± SEM neutrophils/lavage for WT (closed bars) or CD18^−/− (open bars) mice. The data from 0 h of peritonitis (no thioglycollate) are the same as shown in Fig. 5. *Significant differences from WT; ^‡significant differences from 0-h (uninfected) mice (P <0.05).