Supplementation with vitamin D improves HIV+ macrophages phagocytosis in vitro. There is evidence to suggest that administering vitamin D can in fact improve immune function in individuals. The study will evaluate the impact of high dose vitamin D in HIV+ smokers' and HIV- smokers' in vivo. The primary goal is to improve innate immune host response to infection in patients already at high risk by virtue of HIV and smoking status.

Tobacco smoke suppresses the lung's ability to fight infection. Smoking is three times more prevalent in the HIV+ compared to HIV- patients. Viral load was found to be significantly increased in HIV+ smokers compared to HIV+ non-smokers, suggesting that smoking enhances HIV-1 viral replication in macrophages, which contributes to disease progression. Vitamin D deficiency has been associated with increased mortality in HIV+ persons, but there is limited research on how this is impacting the health of these highest risk patients and if aggressive repletion with vitamin D can improve overall health.The study team hypothesizes that vitamin D administration will increase pathogen clearance and improve innate immune function. The proposed pre and post interventional study is designed to characterize alveolar macrophage function and lung immunity according to tobacco use and HIV status, and determine the impact of high dose oral vitamin D3 on AM phagocytic function and innate immunity.