ABSTRACT
The B complex of genes in the chicken is considered analogous to the major histocompatibility complex (MHC) of mammals. Anti-la antisera produced in noncongenic lines of chickens are useful for immunofluorescence and cytotoxic assays, but have generally been ineffective for immunoprecipitation of solubilized antigens. An important consideration in the designation of antigens as Ia antigens is their association with genes that control immunologic functions. Structurally the Ia antigens of chickens are remarkably similar to their mammalian counterparts. In the chicken, Ia antigens have been demonstrated by immunofluorescence on B cells, macrophages, and an unidentified subpopulation of mononuclear cells in bone marrow, spleen, thymus, and bursa of Fabricius. The evidence accumulated thus far indicates that Aves have genes within their major histocompatibility complex that code for antigens resembling the Ia antigens of mammals. The antigens characterized thus far are glycoproteins composed of a heavy and light chain of 32,000 and 27,000 daltons, respectively.
