CD244 and influenza: Many genes involved in T cell and NK cell responses were down-regulated in influenza infected patients regardless of their clinical outcome, however, we found that some keys transcripts in the T cell and NK cell signaling response were only down-regulated in patients with severe influenza (CD244, CD3E, CD4, CD1A, NCR3 and IL10RA) suggesting the important roles of these transcripts in severe influenza.