This notion is supported by our recent observation that phosphoantigen/IL2-expanded Vγ2Vδ2 T effector cells can produce a homeostatic mediator FGF-7, and coincide with attenuation against pneumonic plague damages of lung tissues after pulmonary infection even with extracellular Y. pestis[14], whose protection often requires neutralizing Ab. This evidence concerns the gene IL2 and plague.