A model of allergic pulmonary inflammation is described in which the intraperitoneal injection of antigen (Ag)-pulsed cells resulted in T cell priming. Mice received two injections of 10(6) elicited peritoneal macrophages, which had been incubated with Ag for 48 hr, on Days 0 and 6, followed by an aerosol Ag challenge on Day 19. Bronchoalveolar lavage fluid harvested on Day 21 contained increased eosinophil numbers and resembled the cell influx observed following immunization with Ag in alum. Incubation of Ag-presenting cells with interferon-gamma resulted in increased expression of the costimulator molecule B7-2 and of MHC Ags, but did not enhance priming capacity. Using this system, antibodies to CD4 and CD8 were tested for their ability to block sensitization by Ag-pulsed cells. Both anti-CD4 and anti-CD8 antibodies completely blocked the airway eosinophil response following aerosol Ag challenge. This model will be very useful for characterization of the interactions between Ag-presenting cells and T cells which ultimately result in the induction of pulmonary eosinophilia.