CCR2 and influenza: There are, however, several obstacles on the way: (i) monocytes if low in number or lack CCR2 are not recruited well, which increases the affected organ pathology as is seen in the mouse model of influenza in which a lack of CCR2 on monocytes increases the organ pathology (97); (ii) monocytes are present but lymphocytes fail, not recognizing the epitopes presented by antigen presenting cells due to the low number or poor repertoire of T cells, and (iii) the appropriate cells are present but the immune response is paralyzed by monocytic-myeloid derived suppressor cells.