Systemic Reduction of Interleukin-4 or Interleukin-10 Fails to Reduce the Frequency or Severity of Experimental Cytomegalovirus Retinitis in Mice with Retrovirus-Induced Immunosuppression

Interleukin-4 (IL-4) and interleukin-10 (IL-10) are key cytokines whose increased production during systemic HIV infection has been associated with decreased cellular immunity during AIDS. We examined whether HIV-induced stimulation of IL-4 or IL-10 production leads to increased susceptibility to AIDS-related human cytomegalovirus retinitis. It was confirmed that there were increased amounts of IL-4 and IL-10 mRNA levels in mice with MAIDS of 10 weeks duration when most susceptible to MCMV retinitis. Surprisingly, however, MCMV-infected eyes of IL-4 -/- and IL-10 -/- mice with MAIDS of 8 weeks duration exhibited retinitis and infectious virus equivalent to that observed in MCMV-infected eyes of wild-type mice with MAIDS. We conclude that neither IL-4 nor IL-10 alone play a role in increased susceptibility to MAIDS-related MCMV retinitis, but may work collectively with other retrovirus-induced immunosuppressive factors to allow for retinal disease.