CD4 and influenza: The traditionally accepted role of influenza-specific CD4+ T cells is in providing help to B cells for the production of high-quality Abs (Topham and Doherty, 1998), as their activation is dependent on recognition of peptide in the context of MHC-II on professional APCs but also have a major role in providing help for the establishment of CD8+ T cell memory, critical for a robust recall response (Sun et al., 2004).