An IL-2-toxin, DAB389IL-2, inhibits delayed-type hypersensitivity but enhances IgE antibody production

Expression of high-affinity IL-2 receptor (IL-2R) on T lymphocytes, key cells in chronic inflammation, is a T-cell activation marker.

We sought to evaluate the effect of the fusion protein DAB389IL-2, which kills cells bearing IL-2R, on delayed-type hypersensitivity and antibody production in Brown Norway rats sensitized with trimellitic anhydride (TMA).

DAB389IL-2 (25 micrograms/kg/day) or placebo was administered intraperitoneally for 8 days over the period of sensitization, starting 2 days before sensitization.

The administration of DAB389IL-2 resulted in a one-third reduction in the number of IL-2R-bearing cells and significant weight loss of animals. Delayed-type hypersensitivity, evaluated at 5 weeks after sensitization, was significantly inhibited by treatment with DAB389IL-2. In contrast, production of IgE anti-TMA antibodies after sensitization was increased by treatment with DAB389IL-2. DAB389IL-2 affected neither IgG anti-TMA antibody nor total IgE levels.

These data imply that systemic administration of DAB389IL-2 in Brown Norway rats influences cells that have regulatory effects on the immune system, resulting in a switch from a TH1 to a TH2 type of immune response.