RT Journal Article SR Electronic T1 Complex role of immature myeloid cells in Salmonella Typhimurium infection (P4225) JF The Journal of Immunology JO J. Immunol. FD American Association of Immunologists SP 130.12 OP 130.12 VO 190 IS 1 Supplement A1 Tam, Jason A1 Kullas, Amy A1 Mena, Patricio A1 van der Velden, Adrianus YR 2013 UL http://www.jimmunol.org/content/190/1_Supplement/130.12.abstract AB Immature myeloid cells are a heterogeneous population of cells that, under normal conditions, provide tissues with protective cells (e.g. macrophages, dendritic cells). Under certain pathological conditions, myeloid cell differentiation is overridden and immature forms of these cells accumulate in tissues. Immature myeloid cells that express CD11b and either Ly6C or Ly6G (isoforms of Gr-1) have been associated with immunosuppression in cancer and, more recently, infection. We report that large numbers of CD11b+Ly6Chi Ly6G- and CD11b+Ly6CintLy6G+ cells accumulate and persist in tissues of mice infected with Salmonella Typhimurium. The CD11b+Ly6Chi Ly6G- cells exhibited a mononuclear morphology whereas the CD11b+Ly6Chi Ly6G- cells exhibited polymorphonuclear and ring-shaped nuclear morphologies. The CD11b+Ly6Chi Ly6G- cells expressed surface MHC-I and II, and differentiated into macrophage-like cells following ex vivo culture. The CD11b+Ly6Chi Ly6G- cells were capable of inducing T cell proliferation in vitro, but only when their ability to produce nitric oxide was blocked. The CD11b+Ly6Chi Ly6G- cells also were capable of presenting antigen to T cells in vivo, albeit less efficiently than macrophages. These findings indicate that CD11b+Ly6Chi Ly6G- cells have a complex role in S. Typhimurium infection, providing a balance of immunosuppressive and protective functions where the tipping of this balance may be an important factor influencing the outcome of infection.