JLE

European Cytokine Network

MENU

Role of IL‐10 in the distribution of B cell subsets in the mouse B‐1 cell population Volume 14, numéro 3, July 2003

Auteurs
Laboratory of Immunology, Brest University Medical School Hospital, BP 824, F 29609 Brest, France INSERM Unit 477, Cochin Hospital, René Descartes University, Paris, France

The B lymphocyte compartment is comprised of B‐1 and B‐2 cells. The former is divided into B‐1a, which express CD5, and B‐1b cells which do not: both are self‐renewing, although the mechanisms are yet to be identified. IL‐10 ‐‐\‐‐ mice were used to delineate the role of the B cell activator IL‐10 in this process. Its absence had no effect on the total number of B‐1 cells, but decreased that of B‐1a cells (0.8 ± 0.1  versus 1.7 ± 0.2 × 10 6, p < 0.002), while increasing that of B‐1b cells (1.9 ± 0.4  versus 0.8 ± 0.1 × 10 6, p < 0.03). The number of B‐1a cells remained low in IL‐10‐injected IL‐10 ‐‐\‐‐ mice, whereas the excess of B‐1b cells further increased (2.8 ± 0.2  versus 1.6 ± 0.4 × 10 6, p < 0.03). On the basis that Bax and Bad were augmented in B‐1a cells, and Bcl‐2 and Bcl‐x L reduced, we conclude that the disappearance of B‐1a cells, but not B‐1b, in IL‐10 ‐‐\‐‐ mice results from their enhanced susceptibility to apoptosis. In addition, culture of IL‐10 ‐‐\‐‐ B‐1a and B‐1b cells in the presence of IL‐10 drives more of the latter than of the former into cycle ( p < 0.02). Therefore, IL‐10 exerts two, complementary effects on the distribution of B‐1 cell sub‐populations, rescuing B‐1a cells from apoptosis and encouraging B‐1b cell proliferation.