Systemic administration of interferon-gamma-expressing plasmid reduces late allergic bronchitis in a mouse model of asthma.

Asthma might be caused by a helper T(Th)2 immune response. We hypothesized that the systemic administration of the Th1 cytokines may reduce the Th2 type late asthmatic response (LAR). We examined the effect of the intraperitoneal injection of interferon(IFN)-gamma-expressing plasmid, a Th1 cytokine, or interleukin(IL)-4-expressing plasmid, a Th2 cytokine, at the time of sensitization on a mouse model of asthma induced by ovalbumin in BALB/c mice. We demonstrated that the IFN-gamma-expressing plasmid reduced the LAR, whereas the IL-4-expressing plasmid enhanced the LAR as compared with the saline or plasmid-only treated group. The present study suggests that the systemic administration of IFN-gamma-expressing plasmid may have a modulating ability of Th1/Th2 balance to down-regulate Th2 response by a mutual inhibitory mechanism between Th1 and Th2 cells, leading to the reduction of the LAR.