title: Both the pre-BCR and the IL-7Ralpha are essential for expansion at the pre-BII cell stage in vivo.
abstract: During B cell development, proliferative expansion takes place after expression of the pre-BCR. At this pre-BII cell stage, the IL-7Ralpha is also expressed. Some in vitro studies suggest that pre-BCR-dependent expansion relies on the IL-7Ralpha, and others that it does not. It has also been suggested that the pre-BCR mediates down-regulation of the IL-7Ralpha. However, the in vivo relationship between the pre-BCR and the IL-7Ralpha has not been previously examined. Here, we have investigated this by establishing mice lacking both receptors. Our results show that in the absence of the IL-7Ralpha, the pre-BII population is reduced, as previously seen in mice lacking the pre-BCR, demonstrating that the IL-7Ralpha is important at this stage. A deficiency in both receptors results in a further reduction of the pre-BII cell population. We conclude that both the IL-7Ralpha and the pre-BCR are required for optimal pre-BII cell expansion. Furthermore, IL-7Ralpha expression levels are normal in pre-BCR-deficient mice, suggesting that the pre-BCR does not mediate its down-regulation. As a consequence of the absence of both receptors, the peripheral B cell pool is severely depleted, resulting in atypical splenic B cell structures and reduced serum Ig levels.
authors.affiliation: Laboratory of Lymphocyte Signaling and Development, The Babraham Institute, Cambridge, UK.
authors.forename: Lena
authors.initials: L
authors.lastname: Erlandsson
authors.forename: Steve
authors.initials: S
authors.lastname: Licence
authors.forename: Fabrina
authors.initials: F
authors.lastname: Gaspal
authors.forename: Peter
authors.initials: P
authors.lastname: Lane
authors.forename: Anne E
authors.initials: AE
authors.lastname: Corcoran
authors.forename: Inga-Lill
authors.initials: IL
authors.lastname: Mårtensson
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000502:physiology*; D006412:Hematopoietic Stem Cells / Q000502:physiology*; D007136:Immunoglobulins / Q000097:blood; D051379:Mice; D008822:Mice, Transgenic; D011498:Protein Precursors / Q000502:physiology*; D011947:Receptors, Antigen, B-Cell / Q000502:physiology*; D020395:Receptors, Interleukin-7 / Q000502:physiology*; D013154:Spleen / Q000276:immunology
chemical_list: D007136:Immunoglobulins; D011498:Protein Precursors; D011947:Receptors, Antigen, B-Cell; D020395:Receptors, Interleukin-7; C415350:interleukin-7 receptor, alpha chain