MMPs facilitate leucocyte recruitment, cytokine and chemokine processing, defensin activation and matrix remodeling (181). Inhibition of MMPs in BALB/c mice was deleterious, resulting in decreased IL-1 and IL-2 expression, premature increase in IL-4, delayed granuloma formation, & more rapid progression of TB (263). In contrast, inhibition of MMPs in C57BL/6 mice was salubrious, resulting in increased fibrosis of the granulomas, decreased leukocyte recruitment (to the granulomas), & decreased numbers of Mtb in the lungs & blood in early disease (264). This evidence concerns the gene IL1A and tuberculosis.