The poor prognostic factors of far-advanced pulmonary tuberculosis(FAPTB) are lymphocytopenia in the peripheral blood(PB)(<1,000/mm³) and T₄-cell count ≤500/mm³. However, the cause of PB lymphocytopenia in FAPTB is unclear. The aim of this study was to analyze the lymphocyte proportion and cytokines of the bone marrow(BM) in FAPTB patients with peripheral lymphocytopenia in order to clarify whether the limiting step of the lymphocytopenia occurs in production, differentiation, or circulation.

This study included patients with FAPTB between August 1999 and August 2002 who visited Gachon Medical School Gil Medical Center. The exclusion criteria were old age(≥65years), cachexia or a low body weight, shock, hematologic diseases, or BM involvement of tuberculosis. The distributions of cells in PB and BM were analyzed and compared to the control group. The interleukin(IL)-2, IL-7, IL-10, TNF-α, Interferon-γ, and TGF-β levels in the BM were measured by ELISA.

Thirteen patients(male : female=9:4) were included and the mean age was 42±12years. The proportion and count of the lymphocytes in the PB were significantly lower in the FAPTB group (7.4± 3.0%, 694±255/mm³ vs. 17.5±5.8%, 1,377±436/mm³, each p=0.0001 and 0.002). The proportion of immature lymphocyte in the BM showed a decreasing trend in the FAPTB group(9±4% vs. 12±3%, p=0.138). The IL-2(26.0±29.1 vs. 112.2±42.4pg/mL, p=0.001) and IL-10(3.4±4.7 vs. 12.0±8.0pg/mL, p=0.031) levels in the BM were significantly lower in the FAPTB group than those in control. The levels of the other cytokines in FAPTB group and control were similar.

These results suggest that the cause of lymphocytopenia in PB is associated with a abnormality IL-2 and IL-10 production in the BM. More study will be needed to define the mechanism of a decreased reservoir in BM.