Expression of an immunoglobulin heavy chain transgene in macrophage as well as lymphocyte lineages in vivo

A rearranged immunoglobulin heavy chain (IgH) transgene-encoded protein is expressed in macrophage lineage cells, in addition to B and T lineages, in transgenic mouse bone marrow. Peripheral macrophages also express transgenic IgH protein. Mature T cells express lower levels than immature thymocytes. Almost all B220⁺ cells in the bone marrow express transgenic IgH protein, and this early expression in the B lineage is accompanied by a reduction of cell frequency even in the early B220⁺ CD43⁺ BP-1^- stages, although it is more prominent in BP-1⁺ pre-B cells. Thus, an IgH transgene can be expressed not only in lymphoid but also in myeloid cells, although its developmental effects are restricted to the B cell lineage.