THE MURINE HOMOLOG OF THE HIN-200 FAMILY, IFI-204, IS CONSTITUTIVELY EXPRESSED IN MYELOID CELLS AND SELECTIVELY INDUCED IN THE MONOCYTE MACROPHAGE LINEAGE/

To examine the expression of Ifi 200 genes in vivo and add new informa tion about their function, polyclonal monospecific rabbit antibodies, designated N-term or C-term, were raised against both the N-terminus a nd C-terminus of the 204 protein (p204) respectively. Western blotting analysis demonstrated that p204 and D3, another member of the Ifi 200 gene family, are constitutively expressed, though at different degree s, in bone marrow; thymus and lymph nodes, and barely detectable in th e spleen, Poly rI:rC treatment did not modulate their expression. Peri toneal resident macrophages (M phi) from untreated mice were negative, but displayed high levels of both p204 and D3 on poly rI:rC treatment . A significant increase of these proteins is also observed when M phi are cultured overnight in vitro with IFNs or LPS. Lung, kidney and br ain were negative for p204 and D3 expression, These results, together with immunoistochemical analysis, demonstrate that the 204 gene has an expression pattern restricted to cells of the myelomonocytic lineage similar to that observed for the hunan homolog, the myeloid nuclear di fferentiation antigen (MNDA) suggesting its potential involvement in t he differentiation and maturation of this cell lineage.