CD4 and pneumonia: Adoptive transfer results demonstrated EPS301-adjuvanted vaccination immunized lung CD4 T cells and γδ T cells were crucial for anti-P. aeruginosa induced pneumonia, but immunized spleen CD4 T cells and γδ T cells were dispensable, which, in part, explained the traditional parenteral vaccine were failed to P. aeruginosa pneumonia because of mainly induced systemic immune response.