Detection of Mycobacterial DNA in Human Bone Marrow.

Bone marrow is a cell-rich tissue of the reticuloendothelial system essential in the homeostasis and accurate functioning of hematopoiesis and of the immune system; moreover, it is also rich in lipids because it contains marrow adipocytes. This work aimed to evaluate the detection of mycobacterial DNA in human bone marrow as a tool to understand the complex pathology caused by the main pathogen (). Formalin-fixed paraffin-embedded human bone marrow samples were studied using both conventional PCR + hybridization and PCR to figure out the cell distribution of the targeted DNA. Samples were retrospectively collected from HIV+ patients with microbiologically proved mycobacterial infection and from subjects without evidence of infection. () as well as DNA was detected in both settings, including tissues with and without granulomas. We detected DNA from both mycobacterial species, using PCR, inside bone marrow macrophages. Other cell types, including adipocytes, showed positive signals only for DNA. This result suggested, for the first time, that marrow adipocytes could constitute an ideal reservoir for the persistence of , allowing the bacilli to establish long-lasting latent infection within a suitable lipid environment. This fact might differentiate pathogenic behavior of non-specialized pathogens such as av from that of specialized pathogens such as