Increased production of interleukin 4 by CD4(+) and CD8(+) T cells from patients with tuberculosis is related to the presence of pulmonary cavities

In tuberculosis, cellular immunity is considered to be responsible for the eradication of infection but also for damage of host tissues. In animal mod els, the balance between Th1-type cytokines, especially interferon (IFN)-ga mma, and Th2-type cytokines, primarily interleukin (IL)-4, seems crucial fo r these effects. Reports on Th1-type and Th2-type cytokines in human tuberc ulosis are conflicting, and little is known about their role in tissue dama ge. Flowcytometric assessment of cytokine responses was performed in human immunodeficiency virus (HIV)-seronegative patients with active tuberculosis and in healthy controls. Patients and controls showed no significant diffe rence in expression of IFN-gamma. However, patients showed a striking incre ase in production of IL-4 in CD4(+) as well as CD8(+) T cells. Most remarka bly, the expression of IL-4 was especially elevated in patients with cavita ry tuberculosis. The Th2-type response with increased production of IL-4 in patients with tuberculosis may antagonize host defense and lead to tissue necrosis.