Detection of Mycobacterium tuberculosis DNA in CD34 + peripheral blood mononuclear cells of adults with tuberculosis infection and disease.

OBJECTIVES: To investigate whether Mycobacterium tuberculosis (Mtb) DNA is detected in peripheral blood mononuclear cells (PBMC) of subjects with tuberculosis (TB) or TB infection (TBI) living in a low TB burden country.

METHODS: We prospectively enrolled 57 TB-patients, 41 TBI-subjects and 39 controls in Rome, Italy. PBMC were isolated, CD34+ and CD34- cells were immunomagnetic separated, DNA was extracted and digital PCR for IS6110 and rpoB sequences was used to detect Mtb DNA in PBMC subsets and unfractionated PBMC.

RESULTS: We detected Mtb DNA at low copy number in CD34+ cells in 4/30 (13%) TB-patients, 2/24 (8%) TBI-subjects and 1/24 (4%) controls. Mtb DNA was detected in unfractionated PBMC in 3/51 (6%) TB-patients, 2/38 (5%) TBI-subjects and 2/36 (6%) controls. In CD34- cells only 1/31 (3%) TBI-subject was Mtb DNA positive.

CONCLUSIONS: Mtb DNA was detected at low frequency and levels in PBMC of TBI-subjects and TB-donors living in a low TB burden country. In particular, Mtb DNA was detected more frequently in CD34+ cells, supporting the hypothesis that these cells may represent a Mtb niche. This finding informs biological understanding of Mtb pathogenesis and may support development of a microbial blood biomarker for Mtb infection.