| First Author | Jin H | Year | 2004 |
| Journal | J Immunol | Volume | 173 |
| Issue | 1 | Pages | 657-65 |
| PubMed ID | 15210829 | Mgi Jnum | J:90963 |
| Mgi Id | MGI:3045569 | Doi | 10.4049/jimmunol.173.1.657 |
| Citation | Jin H, et al. (2004) Distinct activation signals determine whether IL-21 induces B cell costimulation, growth arrest, or Bim-dependent apoptosis. J Immunol 173(1):657-65 |
| abstractText | IL-21 costimulates B cell proliferation and cooperatively with IL-4 promotes T cell-dependent Ab responses. Somewhat paradoxically, IL-21 also induces apoptosis of B cells. The present study was undertaken to more precisely define the expression of the IL-21R, using a novel mAb, and the circumstances by which IL-21 promotes B cell growth vs death. The IL-21R was first detected during T and B cell development, such that this receptor is expressed by all mature lymphocytes. The IL-21R was further up-regulated after B and T activation, with the highest expression by activated B cells. Functional studies demonstrated that IL-21 substantially inhibited proliferation and induced Bim-dependent apoptosis for LPS or CpG DNA-activated B cells. In contrast, IL-21 induced both costimulation and apoptosis for anti-CD40-stimulated B cells, whereas IL-21 primarily costimulated B cells activated by anti-IgM or anti-IgM plus anti-CD40. Upon blocking apoptosis using C57BL/6 Bim-deficient or Bcl-2 transgenic B cells, IL-21 readily costimulated responses to anti-CD40 while proliferation to LPS was still inhibited. Engagement of CD40 or the BCR plus CD40 prevented the inhibitory effect by IL-21 for LPS-activated B cells. Collectively, these data indicate that there are three separable outcomes for IL-21-stimulated B cells: apoptosis, growth arrest, or costimulation. We favor a model in which IL-21 promotes B cell maturation during a productive T cell-dependent B cell response, while favoring growth arrest and apoptosis for nonspecifically or inappropriately activated B cells. |
