IL15 and infection: Hence, we determined circulating IL-15 levels and observed that during the chronic stage of disease (8 weeks of infection) resistant NLRP3−/− mice produced higher levels of this lymphocyte growth factor, as compared to those found in WT mice (1540 ± 240 pg/mL versus 853 ± 130 pg/ml, respectively) (Fig. 4d), indeed, IL-15 levels were higher in NLRP3−/− mice starting on week 6 (data not shown).