The human counterpart of mouse B-1 cells.

B-1 cells represent a subpopulation of B cells that has been extensively studied in mice and shown to spontaneously generate natural antibody that provides antimicrobial protection and helps dispose of cellular debris. Mouse B-1 cells originate from distinct progenitors and express additional immune properties that include phagocytosis, antigen presentation, immune suppression, and polarization of T cell differentiation. Confusion regarding the existence of human B-1 cells with mouse B-1-like properties has recently been addressed by identification of a new phenotypic profile. Human B-1 cells spontaneously secrete antibody and are distinct from other circulating B cell populations by multiple criteria. A number of laboratories have recently reported on changes to the human B-1 cell population in human disease.