The role of adaptive immune responses mediated by antigen specific Th17 has been investigated more recently. Antigen specific Th17 cells were also shown to recognize conserved protein antigens among different K. pneumoniae strains and provide broad-spectrum serotype-independent protection.  Antigen specific CD4 T cells also limit nasopharyngeal colonization of S. pneumoniae in mouse models.  Furthermore, immunization with pneumococcal whole cell antigen and several derivatives provided IL-17-mediated, but not antibody dependent, protection against S. pneumoniae challenge.   In fungal infection, it has been shown an IL-17 producing clone with a TCR specific for calnexin from Blastomyces dermatitidis confers protection with evolutionary related fungal species including Histoplasma spp.