ABSTRACT

B-1 cells are a distinct subset of B cells committed to the production of natural antibodies. B-1 cells appear early in ontogeny and are distinguished from conventional B-2 cells by their expression of CD5, a cysteine-rich transmembrane protein (6). CD5 appears to modulate the response to antigen receptor engagement and, in autoreactive B cells, may limit cellular activation and proliferation in the context of antigen binding.