In macrophages and monocytes, cellular sensing of pathogens, such as Mycobacterium tuberculosis, by pattern recognition receptors, such as Toll-like receptors, enhances expression of CYP27B1 and the VDR, thereby increasing intracrine synthesis and activity of 1,25(OH)2D3.4 The resulting effects, including enhanced expression of the antibacterial proteins cathelicidin and ??-defensin 2, and enhance