Abstract
B-1 cells are classified as B-lymphocytes because they rearrange immunoglobulin genes, synthesize IgM and IgD and express characteristic lymphocyte surface molecules (B-220 and CD19). These cells also express macrophage surface markers (CD11b and F4/80). They differentiate in vitro into a mononuclear phagocyte, provisionally named lymphophage. Although they show some characteristics of ma…