Mast cells protect mice from Mycoplasma pneumonia.

Rationale: As the smallest free-living bacteria and a frequent cause of respiratory infections, mycoplasmas are unique pathogens. Mice infected with Mycoplasma pulmonis can develop localized, life-long airway infection accompanied by persistent inflammation and remodeling.Objective: Because mast cells protect mice from acute septic peritonitis and gram-negative pneumonia, we hypothesized that they defend against mycoplasma infection. This study tests this hypothesis using mast cell–deficient mice.Methods: Responses to airway infection with M. pulmonis were compared in wild-type and mast cell–deficient KitW-sh/KitW-sh mice and sham-infected control mice.Measurements and Main Results: Endpoints include mortality, body and lymph node weight, mycoplasma antibody titer, and lung mycoplasma burden and histopathology at intervals after infection. The results reveal that infected KitW-sh/KitW-sh mice, compared with other groups, lose more weight and are more likely to die. Live mycoplasma burden is greater in Kit...