IL10 and infection: A first group of mice mildly colonized (between 5.105 and 2.107 CFU) showed intermediate level of IL-10 (between 70 and 200 pg/ml) while a second group of mice that were unable to control the infection (> 2.107 CFU) were characterized by an intense production of IL-10 (> 103 pg/ml) suggesting that KR is able to induce an intense production of IL-10 only above a certain threshold of KR bacteria in the lungs.