Abstract
Objective. Recombinant human (rHu) interleukin (IL)-12 has been shown to reduce levels of blood and sputum eosinophils in patients with mild allergic asthma in a randomized controlled study. The aim of the study was to investigate whether four escalating weekly subcutaneous injections of rHuIL-12 in allergic asthmatic patients could induce changes in the intracellular cytokine profile of the circulating blood CD4+ and CD8+ T cells. Material and methods. Purified CD4+ and CD8+ T cells from peripheral blood mononuclear cells of 11 patients (six received rHuIL-12 and five received placebo) were collected before and after 4 weeks of treatment, and cultured in the presence of phorbol myristate acetate for 4 days, with or without the addition of IL-12 in vitro. Expression of various intracellular cytokines was determined using flow cytometry following treatment with brefeldin-A and saponin. Results. Compared to placebo, the proportions of peripheral blood interferon-γ-, IL-4-, IL-2- or IL-10-producing CD4+ or CD8+ T cells were not significantly changed following rHuIL-12 treatment. Conclusion. Four weekly treatments with rHuIL-12 do not produce peripheral blood T-cell changes detectable with our experimental setting and methodology.