Inoculation route-dependent effects of BCG on asthmatic airway histology

Lin, Xiang Hua; Choi, Inseon S; Koh, Young Ah

Abstract

BACKGROUND: Intranasal (i.n.), as compared with subcutaneous (s.c.), BCG vaccination causes a greater suppression of airway eosinophilia. A comprehensive examination is needed to confirm that in various asthma models.
METHODS
BALB/c mice were immunized with i.n. or s.c. inoculation of BCG 1 x 10(5) CFUs. Sensitization and provocaton using ovalbumin (OVA) or Dermatophagoides farinae (Der f) were started at the same time or 1 week after the immunization. And then, a bronchoalveolar lavage (BAL) and an examination of lung tissue using a computerized image analyzer program were performed.
RESULTS
Both the i.n.- and s.c.- BCG infections reduced eosinophilia in both the BAL fluids and the lung tissues of both OVA- and Der f- asthma models. The proportions of BAL fluid lymphocyte in the mice infected with i.n. BCG were significantly lower than those with s.c. BCG (1.60+/-0.39% vs. 3.42+/-0.37%, p<0.01). However, the s.c.- as compared with i.n.- route caused a greater suppression in peribronchial eosinophilia [small (<500 micrometer) airways: 43.9+/-12.5 vs 89.5+/-20.0/mm2, p=0.08; large (>1,000 micrometer) airways: 17.4+/-3.2 vs 37.0+/-5.9/mm2, p<0.05]. The goblet cell proportions in epithelium were also significantly lower in the mice received s.c.- as compared with i.n.- BCG (0.29+/-0.18 vs 0.43+/-0.20, p<0.01).
CONCLUSIONS
These results suggest that both i.n.- and s.c.- BCG inoculations reduce eosinophilia in airways, but the s.c. route is more effective in the suppression of the asthmatic responses in lung tissue.