High-Dimensional Characterization of IL-10 Production and IL-10–Dependent Regulation during Primary Gammaherpesvirus Infection

IL-10 is a potent immunomodulatory cytokine produced by multiple cell types to restrain immune activation. Many herpesviruses use the IL-10 pathway to facilitate infection, but how endogenous IL-10 is regulated during primary infection in vivo remains poorly characterized. In this study, we infected mice with murine gammaherpesvirus 68 (γHV68) and analyzed the production and genetic contribution of IL-10 by mass cytometry (cytometry by time-of-flight) analysis. γHV68 infection elicited a breadth of effector CD4 T cells in the lungs of acutely infected mice, including a highly activated effector subset that coexpressed IFN-γ, TNF-α, and IL-10. By using IL-10 GFP transcriptional reporter mice, we identified that IL-10 was primarily expressed within CD4 T cells during acute infection in the lungs. IL10gfp-expressing CD4 T cells were highly proliferative and characterized by the expression of multiple coinhibitory receptors, including PD-1 and LAG-3. When we analyzed acute γHV68 infection of IL-10–deficient mice, we found that IL-10 limits the frequency of both myeloid and effector CD4 T cell subsets in the infected lung, with minimal changes at a distant mucosal site. These data emphasize the unique insights that high-dimensional analysis can afford in investigating antiviral immunity and provide new insights into the breadth, phenotype, and function of IL-10–expressing effector CD4 T cells during acute virus infection.