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

The amino acid (aa) sequence 190–289 of the RSV fusion (F) glycoprotein expressed in insect cells (bF 190–289) has been shown to partially protect BALB/c mice and to prime for a Th2 cell response. We evaluated the effects of IL-12 treatment during antigen priming of bF 190–289 on immune response and protective efficacy. Low doses of IL-12 (10 ng) reduced IL-4 and IL-5 secretion (but did not affect IL-10 production) and decreased inflammatory signs 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 IL-12 treatment attenuates Th2 response and Th2 associated pulmonary inflammatory response in a dose-dependent manner, without improving protective efficacy.