Acquired immunity to Chlamydia pneumoniae is dependent on gamma interferonin two mouse strains that initially differ in this respect after primary challenge

The role of gamma interferon (IFN-gamma) in a Chlamydia pneumoniae mouse mo del was studied by in vivo neutralization in two inbred mouse strains. Duri ng primary C. pneumoniae infection, neutralization of IFN-gamma increased b oth the numbers of bacteria and the pneumonia score in the Lungs of C57BL/6 mice but not BALB/c mice. During reinfection, the bacterial counts in the lungs were increased by IFN-gamma neutralization in both mouse strains. Thu s, the effect of IFN-gamma neutralization was dependent on the genetic back ground in primary infection. However, IFN-gamma appeared to be equally impo rtant in both mouse strains during reinfection.