Elevation of soluble IL-2 receptor and IL-4, and nonelevation of IFN-gamma in sera from patients with allergic asthma.

To determine whether the predominant in vivo activation of Th1 subset or Th2 subset in peripheral blood occurs in patients with allergic asthma, we measured serum levels of Th1 cell-derived interferon-gamma (IFN-gamma) and Th2 cell-derived interleukin-4 (IL-4). In addition, serum levels of soluble interleukin-2 receptor (sIL-2R) released from activated T cells were measured to determine a potential source of these cytokines. The elevation of serum IL-4 levels and nonelevation of serum IFN-gamma levels were observed in patients with allergic asthma compared with normal control subjects. A significant correlation between serum IL-4 levels and serum sIL-2R levels was observed in these patients. These results suggest that there is allergen-induced in vivo activation of Th2-like cells in peripheral blood of patients with allergic asthma.