ABSTRACT
BACKGROUND: B-1 cells differ from conventional B-2 cells both phenotypically and functionally. The aim of this study was to investigate the difference between peritoneal B-1 cells and splenic B-2 cells in proliferation. METHODS: We obtained sorted B-1 cells from peritoneal fluid and B-2 cells from spleens of mice. During the culture of these cells, immunoglobulin secreted into the culture supernatants was evaluated by enzyme- linked immunosorbent assay. Entering of S phase in response to LPS-stimuli was measured by proliferative assay. RESULTS: Spontaneous Immunoglobulin M production occurred in peritoneal B-1 cells but not in splenic B-2 cells. LPS stimulated peritoneal B-1 cells secreted IgM at day 1, but splenic B-2 cells at day 2. In thymidine incorporation, peritoneal B-1 cells entered actively S phase after 24hours LPS-stimulation but splenic B-2 cells entered actively S phase after 48 hours. CONCLUSION: IgM secretion and S phase entering occurred early in peritoneal B-1 cells compared to splenic B-2 cells.