title: Comparison of immunoglobulin heavy chain isotype expression in Peyer's patch and splenic B-cells.
abstract: Past work has shown that B lymphocytes from Peyer's patches (PP) and from spleen differ from each other in the following ways: (1) PP are enriched for IgA-producing precursor cells while splenic B-cells are a rich source of IgM-precursor cells; and (2) PP are a poor source of antibody-secreting cells when compared to the spleen. The reasons for these differences are unclear. In this work B-cells have been examined expressing newly regenerated surface immunoglobulin heavy chains in murine PP and spleens for immunoglobulin isotype expression. Dual color immunofluorescence demonstrated higher levels of B-cells regenerating two surface isotypes in the PP (IgM+ IgG+ = 14.9%; IgM+ IgA+ = 9.4%) than in the spleen (IgM+ IgG+ = 0.4%; IgM+ IgA+ = 0.2%). Poly A+ RNA was purified from these B-cells and compared for immunoglobulin heavy chain isotype expression by DNA-excess slot blot hybridization. Splenic B-cells contained higher amounts (at least two-fold) of Ig heavy chain-specific mRNA per microgram of polysomal RNA than did PP B-cells. Peyer's patches B-cells demonstrated slightly lower mu:alpha ratios than splenic B-cells. In vitro translation of the RNAs suggested higher levels of translatable alpha-specific Poly A+ RNA in PP B-cells than in B-cells from MLN or spleen; furthermore, splenic B-cell RNA contained higher levels of translatable mu-RNA than did the other tissues examined. Northern blot analysis of RNA derived from these tissues identified major mu-, gamma 2b-, and alpha-hybridizing sequences, though PP-derived B-cell preparations were shown to be enriched for the membrane forms of mRNA for gamma 2b and alpha when compared to the spleen-derived B-cell preparations. These results suggest that the level of differentiation of PP B-cells (that are capable of regeneration of surface Ig) may differ significantly from that of splenic B-cells.
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000032:analysis; D001402:B-Lymphocytes / Q000276:immunology*; D006824:Hybridization, Genetic; D007143:Immunoglobulin Heavy Chains / Q000032:analysis* / Q000235:genetics; D051379:Mice; D008808:Mice, Inbred CBA; D010581:Peyer's Patches / Q000032:analysis / Q000166:cytology / Q000276:immunology*; D012313:RNA / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D013154:Spleen / Q000032:analysis / Q000166:cytology / Q000276:immunology*
chemical_list: D000954:Antigens, Surface; D007143:Immunoglobulin Heavy Chains; D012333:RNA, Messenger; D012313:RNA