title: De novo expression of MECA-79 glycoprotein-determinant on developing B lymphocytes in gut-associated lymphoid tissues.
abstract: Rabbit is one of several species that depend on development of B lymphocytes in gut-associated lymphoid tissues for primary immunoglobulin-repertoire diversification. The rabbit appendix is an important site of early B-lymphocyte development. We previously reported that peripheral lymph node addressin detected by monoclonal antibody (mAb) MECA-79 played a role in recruitment of immature blood-borne B cells into neonatal rabbit appendix. Here, we report expression of an approximately 127 000 MW O-linked sulphated proteoglycan on developing B cells in appendix and Peyer's patches recognized by the mAb MECA-79. Binding of the mAb to B lymphocytes was sensitive to enzyme treatment with O-sialoglycoprotease and expression was partially inhibited by sodium chlorate, a metabolic inhibitor of sulphation. The proportions of MECA-79(+) B lymphocytes gradually increased from < 0.5% at 3 days to > 70% at 6 weeks in appendix and Peyer's patches. The proportions of MECA-79(+) B lymphocytes in spleen and peripheral blood were very low (0.5-2%). However, the MECA-79 determinant was detected on B cells in splenic germinal centres after immunization. In situ labelling of appendix cells showed that the MECA-79 determinant was expressed on fluorescein-labelled B lymphocytes that migrated from appendix into mesenteric lymph nodes. B-cell MECA-79 may be involved in interactions with T cells and/or dendritic cells. Alternatively, because we found that lymphatic endothelium in the thymus-dependent area of appendix, a site for lymphocyte exit, expressed P-selectin (CD62P), interaction of the MECA-79 determinant on B cells with CD62P may have a role in the exit of B lymphocytes from rabbit appendix.
authors.affiliation: Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA. rsinha@niaid.nih.gov
authors.forename: Rajesh K
authors.initials: RK
authors.lastname: Sinha
authors.forename: Guibin
authors.initials: G
authors.lastname: Yang
authors.forename: Cornelius
authors.initials: C
authors.lastname: Alexander
authors.forename: Rose G
authors.initials: RG
authors.lastname: Mage
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000378:metabolism*; D001065:Appendix / Q000276:immunology*; D001402:B-Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D002634:Chemotaxis, Leukocyte / Q000276:immunology; D002704:Chlorates / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006023:Glycoproteins / Q000378:metabolism; D008198:Lymph Nodes / Q000276:immunology; D008221:Lymphoid Tissue / Q000276:immunology*; D008565:Membrane Proteins / Q000378:metabolism*; D008643:Mesentery; D019007:P-Selectin / Q000378:metabolism; D010581:Peyer's Patches / Q000276:immunology; D011817:Rabbits; D012795:Sialoglycoproteins / Q000276:immunology; D013154:Spleen / Q000276:immunology
chemical_list: D000954:Antigens, Surface; D002704:Chlorates; D006023:Glycoproteins; C069886:L-selectin counter-receptors; D008565:Membrane Proteins; D019007:P-Selectin; D012795:Sialoglycoproteins; C032706:sodium chlorate