IN-VITRO CHARACTERIZATION OF RAT BONE-MARROW-DERIVED DENDRITIC CELLS AND THEIR PRECURSORS

Although the rat is commonly used for basic immunology and transplanta tion research, phenotypic and functional characterization of rat dendr itic cells (DCs) lags behind similar studies in the human and mouse, T herefore, these features were examined using DCs propagated from cultu res of rat bone marrow maintained hi a medium supplemented with granul ocyte-monocyte colony-stimulating factor. Analysis of cytospin prepara tions of cultured cells showed that DCs arise from OX7(+) myelomonocyt ic precursors, Typical mature rat DCs were morphologically similar to their mouse and human counterparts and expressed major histocompatibil ity complex (MHC) class II (common part determinant of Ia), OX62 (inte grin molecule), OX7 (CD90), ICAM-1 (CD54), and CTLA4 counterreceptor, but were negative for OX8 (CD8), OX19 (CD5), W3/25 (CD4), and ED2, a r at macrophage marker. Functional analysis of OX62 + sorted DCs showed that they could effectively present the soluble antigen ovalbumin to n aive T cells in vitro. A combination of anti-MHC class II monoclonal a ntibody and CTLA4-immunoglobulin inhibited allostimulatory ability mor e effectively than either reagent alone, Implications for studying the role of DCs in immune responses in the rat are discussed.