Phenotypically activated γδ T lymphocytes in the peripheral blood of patients with tuberculosis

Surface molecules with the potential relevance for resistance against Mycobacterium tuberculosis were investigated. The expression of lymphocyte function antigen-1, very late antigen (VLA)-4, L-selectin, intercellular adhesion molecule (ICAM)-1, major histocompatibility complex class II, Fas, and CD40 on alpha beta T cells, gamma delta T cells, NK cells, and monocytes of healthy donors and patients with tuberculosis were analyzed. A high activation status of gamma delta T cells and increased levels of soluble ICAM-1 in plasma of patients with tuberculosis versus healthy individuals was detected. Tuberculosis patients with and without an underlying systemic disease could be segregated by differential expression of VLA-4 and ICAM-1 on gamma delta T cells and on monocytes. The composition of peripheral blood mononuclear cells varied slightly, whereas the proportion of monocytes decreased significantly in patients with tuberculosis, compared with healthy controls. The activation phenotype of peripheral gamma delta T cells in patients with tuberculosis emphasizes the role of these T cells in controlling the inflammatory process during tuberculosis and perhaps other microbial infections.