Antibacterial effects of vitamin D
Mr. M. Hawison has couple of interesting papers on pubmed:
Studies of innate immune responses to pathogens such as Mycobacterium tuberculosis have shown that pathogen-recognition receptor-mediated activation of localized vitamin D metabolism and signaling is a key event associated with infection. Vitamin D, acting in an intracrine fashion, is able to induce expression of antibacterial proteins and enhance the environment in which they function. The net effect of these actions is to support increased bacterial killing in a variety of cell types. The efficacy of such a response is highly dependent on vitamin D status; in other words, the availability of circulating 25-hydroxyvitamin D for intracrine conversion to active 1,25-dihydroxyvitamin D by the enzyme 25-hydroxyvitamin D-1α-hydroxylase.
More articles about D from Hewison can be found on http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=search&term=Hewison%20M.