Curtailing infection

Certain crafty viruses can cause the host's immune system to suppress itself, and thereby establish persistent chronic infection. But Ejrnaes et al. (page 2461) and Brooks et al. (Nat. Med. doi:10.1038/nm1492) have now found that suppressing the suppressor, which they show is the cytokine IL-10, can fight persistent infection.

IL-10 is known to exert a suppressive effect on cells of the immune system, including T cells and antigen-presenting cells, and elevated levels of IL-10 have been observed during persistent infection with hepatitis C virus, human immunodeficiency virus, and Epstein-Barr virus.

Now, both teams have observed that mice lacking IL-10 are resistant to persistent infection with lymphocytic choriomeningitis virus (LCMV). They also show that normal mice infected with LCMV have increased IL-10 production and decreased numbers of virus-killing CD8...