Type 2 cytokine gene activation and its relationship to extent of disease in patients with tuberculosis

The extent of type 2 cytokine gene expression in patients with pulmonary tu berculosis (TB) was studied by use of quantitative nested reverse-transcrip tion polymerase chain reaction on freshly isolated peripheral blood mononuc lear cells. Interleukin (IL)-4 and IL-13 mRNA expression was significantly greater in patients-median mRNA copy numbers were 1.7 and 1.1 log(10) highe r, respectively-than in matched tuberculin-positive control subjects. Signi ficant correlations with radiologic extent of disease and serum IgE levels supported the biologic significance of these results. Interferon-gamma mRNA copy numbers exceeded those of type 2 cytokines but were only marginally l ower in patients than in control subjects. Gene expression of an IL-4 splic e variant (IL-4 delta 2) was bimodally distributed in both patient and cont rol groups. Patients with greater IL-4 delta 2 expression also expressed mo re IL-4 mRNA and had more extensive disease. Type 2 cytokines are associate d with immunopathologic changes in TB patients but could be a cause or cons equence of disease.