Dose-dependent effects of IL-12 treatment to immune response induced afterimmunization with a recombinant respiratory syncytial virus (RSV) fusion protein fragment

The amino acid (aa) sequence 190-289 of the RSV fusion (F) glycoprotein exp ressed in insect cells (bF(190-289)) has been shown to partially protect BA LB/c mice and to prime for a Th2 cell response. We evaluated the effects of IL-12 treatment during antigen priming of bF190-289 on immune response and protective efficacy. Low doses of IL-12 (10 ng) reduced IL-4 and IL-5 secr etion (but did not affect IL-10 production) and decreased inflammatory sign s whereas high doses of IL-12 had no effects. In addition, IL-12 treatment did not improve resistance to RSV replication. These results suggest that I L-12 treatment attenuates Th2 response and Th2 associated pulmonary inflamm atory response in a dose-dependent manner, without improving protective eff icacy. (C) 1999 Elsevier Science Ltd. All rights reserved.