title: Two distinct pathways of B-cell development in Peyer's patches.
abstract: The developmental biology of sheep ileal and jejunal Peyer's patches (PP) was investigated using corticosteroids to deplete immature B lymphocytes. During a 7-day treatment with dexamethasone, ileal PP follicular (iPf)B-cell proliferation was arrested and most iPfB-cells died. This resulted in follicular involution with the survival of mesenchymal cells. No iPfB-cell proliferation was detected in follicular remnants for 4 weeks postdexamethasone treatment, and during a subsequent 3-month period, there was limited iPfB-cell proliferation that resulted in a partial regeneration of follicles. Ileal PP involution was also associated with a severe B lymphopenia that persisted for over 14 weeks and was characterized by the survival of primarily isotype-switched and CD5+ sIgM+ B-cells in blood. In contrast, the size of jejunal PP follicles was reduced following dexamethasone treatment, but intrafollicular B-cell proliferation was not arrested. Furthermore, within 4 weeks, the jejunal PP follicles had recovered in size and cellularity and there was no disruption in IgA plasma-cell production. Thus, dexamethasone selectively depleted iPfB-cells and revealed that the ileal and jejunal PPs contain functionally distinct B-cell populations. The partial regeneration of the iPfB-cell population indicated that either an intrafollicular, corticosteroid-resistant B-stem cell existed or that ileal PP follicles can be repopulated by circulating B-cells. Finally, the association between ileal PP involution and the absence of circulating, CD5- B-cells confirmed that this lymphoid tissue provides an essential environment for conventional sIgM+ B-cell development.
authors.affiliation: Basel Institute for Immunology, Switzerland.
authors.forename: P J
authors.initials: PJ
authors.lastname: Griebel
authors.forename: B
authors.initials: B
authors.lastname: Kugelberg
authors.forename: G
authors.initials: G
authors.lastname: Ferrari
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000096:biosynthesis; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D001772:Blood Cell Count; D002454:Cell Differentiation; D019070:Cell Lineage; D003907:Dexamethasone / Q000494:pharmacology; D007082:Ileum / Q000033:anatomy & histology / Q000187:drug effects / Q000276:immunology; D007583:Jejunum / Q000033:anatomy & histology / Q000187:drug effects / Q000276:immunology; D010581:Peyer's Patches / Q000033:anatomy & histology / Q000276:immunology*; D017452:Receptors, IgG / Q000096:biosynthesis; D012756:Sheep; D013601:T-Lymphocytes / Q000187:drug effects; D013950:Thymus Gland / Q000033:anatomy & histology / Q000187:drug effects / Q000276:immunology
chemical_list: D015703:Antigens, CD; D017452:Receptors, IgG; D003907:Dexamethasone