Comparison of Asthma Phenotypes Using Different Sensitizing Protocols in Mice

BACKGROUND Several methods have been reported to induce asthmatic reactions in mice but few studies have compared their efficiency. We evaluated the efficiency of the protocols frequently used in the literature. METHODS BALB/c mice were sensitized to ovalbumin (OVA) by intraperitoneal injection; 1] Once a week for two weeks using OVA with alum (IPOA-2) or without (IPO-2), and provocation on days 28-30 by 1% OVA inhalation; 2] seven times for two weeks by OVA with alum (IPOA-7) or without (IPO-7) and provocation by 1% OVA inhalation on days 42-44. 3] Sensitization by 1% OVA inhalation for ten days (IHO-10) and provocation by 1% OVA inhalation on days 28-30. After the last challenge, airway hyperresponsiveness was measured with single chamber plethysmography 24 hours later and mice were sacrificed 48 hours later. RESULTS Airway hyperresponsiveness, BALF eosinophilia, airway inflammation, and OVA-specific IgE and IgG1 production were effectively induced in IPOA-2, IPOA-7, and IPO-7. However, these phenotypes were not induced in IPO-2 (except for increased BALF eosinophils) or IHO-10 (except for an increased OVA-specific IgG1 level). CONCLUSION The intraperitoneal injections of OVA with alum once a week for two weeks proved to be the most efficient sensitization method of inducing an asthmatic reaction in mice.