title: Interleukin 9-induced in vivo expansion of the B-1 lymphocyte population.
abstract: The activity of interleukin (IL)-9 on B cells was analyzed in vivo using transgenic mice that constitutively express this cytokine. These mice show an increase in both baseline and antigen-specific immunoglobulin concentrations for all isotypes tested. Analysis of B cell populations showed a specific expansion of Mac-1(+) B-1 cells in the peritoneal and pleuropericardial cavities, and in the blood of IL-9 transgenic mice. In normal mice, the IL-9 receptor was found to be expressed by CD5(+) as well as CD5(-) B-1 cells, and repeated injections of IL-9 resulted in accumulation of B-1 cells in the peritoneal cavity, as observed in transgenic animals. Unlike other mouse models, such as IL-5 transgenic mice, in which expansion of the B-1 population is associated with high levels of autoantibodies, IL-9 did not stimulate the production of autoantibodies in vivo, and most of the expanded cells were found to belong to the B-1b subset (IgM+Mac-1(+)CD5(-)). In addition, we found that these IL-9-expanded B-1b cells do not share the well-documented antibromelain-treated red blood cell specificity of CD5(+) B-1a cells. The increase of antigen-specific antibody concentration in immunized mice suggests that these B-1 cells are directly or indirectly involved in antibody responses in IL-9 transgenic mice.
authors.affiliation: Ludwig Institute for Cancer Research, Experimental Medicine Unit, University of Louvain, B-1200 Brussels, Belgium. vink@licr.ucl.ac.be
authors.forename: A
authors.initials: A
authors.lastname: Vink
authors.forename: G
authors.initials: G
authors.lastname: Warnier
authors.forename: F
authors.initials: F
authors.lastname: Brombacher
authors.forename: J C
authors.initials: JC
authors.lastname: Renauld
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology* / Q000378:metabolism; D002452:Cell Count; D005260:Female; D007136:Immunoglobulins / Q000096:biosynthesis; D015848:Interleukin-5 / Q000378:metabolism; D016906:Interleukin-9 / Q000235:genetics / Q000378:metabolism*; D008221:Lymphoid Tissue / Q000166:cytology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D010537:Peritoneum / Q000166:cytology; D018123:Receptors, Interleukin / Q000096:biosynthesis; D053651:Receptors, Interleukin-9
chemical_list: D007136:Immunoglobulins; D015848:Interleukin-5; D016906:Interleukin-9; D018123:Receptors, Interleukin; D053651:Receptors, Interleukin-9