Cooperation between Th1 and Th2 cells in a murine model of eosinophilic airway inflammation

We have studied the actions of helper T lymphocyte-1 and -2 (Th1 and Th2) c ells in an acute model of eosinophilic airway inflammation by infusing chic ken ovalbumin-specific (OVA-specific) Th1 cells, Th2 cells, or both into un sensitized mice and challenging the mice with an OVA aerosol. OVA challenge after infusion of Th1 cells alone resulted in airway inflammation with lym phocytes and monocytes. Challenge after the infusion of Th2 cells alone res ulted in minimal inflammation. In contrast, when Th1 and Th2 cells were tra nsferred together, they cooperated to promote a robust eosinophil-predomina nt inflammatory response. Th1 cells alone were readily recruited to the air ways after challenge, but in the absence of Th1 cells, Th2 cells did not ac cumulate in the airways. When transferred together, both Th1 and Th2 cells, as well as endogenous eosinophils, were effectively recruited. This recrui tment was correlated with increased VCAM-1 expression in the medium- and la rge-sized vessels of the lung and could be inhibited by treating the mice w ith neutralizing antibodies to TNF-alpha or VCAM-1. These data indicate tha t Th2 cells require signals in addition to antigen for their effective recr uitment to the airways. Th1 cells can provide these signals.