Airway exposure to hypochlorite prior to ovalbumin induces airway hyperreactivity without evidence for allergic sensitization

Some epidemiologic studies have indicated that attendance to chlorinated swimming pools is associated with airway hyperreactivity (AHR), allergies and asthma. To investigate the effects of sodium hypochlorite (NaClO), the main pool disinfectant, on allergic sensitization and airway inflammation in mice. In a first series of experiments, mice were sensitized to ovalbumin (OVA), followed by OVA aerosols with or without prior nasal instillation of NaClO (3ppm active chlorine). In a second series, naïve mice received 1-7 nasal instillations of OVA, 10min after instillations of NaClO or water. After 1, 3, 5 and 7 exposures airway reactivity to methacholine, cellular inflammation in bronchoalveolar lavage (BAL), serum OVA-specific IgEs and lung Th2 cytokines were measured. In the first mouse model, airway allergy parameters were not significantly altered upon NaClO administration. However in the second model, NaClO exposure prior to OVA did induce AHR, already after 1 combined application. Combined NaClO+OVA exposure did not lead to an influx of inflammatory cells in BAL fluid or production of anti-OVA IgEs. No AHR developed when OVA was heat-denatured, pre-chlorinated, or replaced by bovine serum albumin or lipopolysaccharide. Nasal instillation of NaClO prior to OVA induces AHR without allergic sensitization. This response is OVA-specific