title: Administration of anti-CD45 mAb specific for a B cell-restricted epitope abrogates the B cell response to a T-dependent antigen in vivo.
abstract: CD45 is a receptor-like protein tyrosine phosphatase expressed exclusively by cells of the hemopoietic lineage. Studies in vitro involving treatment of B cells with anti-CD45 mAb have demonstrated that ligand binding to CD45 alters the cell's response to various activation/differentiation stimuli. In general anti-CD45 treatment has been shown to exert an inhibitory effect on early activation events resulting in the failure of quiescent B cells to enter the cell cycle. These studies suggest that CD45 acts as an important regulatory molecule in vitro, that controls B cell function. In contrast, little is known concerning the role that CD45 plays in vivo regarding regulation of B cell activation and differentiation in response to T-dependent Ag. In our study the anti-CD45 mAb RA3.6B2, which recognizes a B cell-restricted epitope, was used to examine this question. Administration of anti-CD45 mAb in vivo was found to inhibit the proliferative response of splenocytes when stimulated with B cell-, but not T cell-specific mitogens. Immunization with the T-dependent Ag FITC-KLH in the presence of increasing amounts of anti-CD45 mAb resulted in a significant, dose-dependent inhibition of the plaque-forming cell response. Additionally, anti-CD45 mAb inhibited the production of FITC-specific serum antibodies indicating that the effect was systemic. Finally, anti-CD45 mAb appeared to exert a maximal effect at earlier time points, within 48 h of Ag administration, suggesting that B cell activation was primarily affected. These results provide evidence to support the conclusion that CD45 is an important regulatory molecule that is involved in the control of B cell activation in vivo.
authors.affiliation: Department of Microbiology, University of Texas Medical Branch, Galveston 77555-1019.
authors.forename: R
authors.initials: R
authors.lastname: Domiati-Saad
authors.forename: E W
authors.initials: EW
authors.lastname: Ogle
authors.forename: L B
authors.initials: LB
authors.lastname: Justement
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000917:Antibody Formation; D000941:Antigens / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D000939:Epitopes; D006433:Hemocyanins / Q000276:immunology; D017493:Leukocyte Common Antigens / Q000276:immunology / Q000502:physiology*; D007958:Leukocyte Count; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D051381:Rats; D013601:T-Lymphocytes / Q000502:physiology*
chemical_list: D000911:Antibodies, Monoclonal; D000941:Antigens; D000939:Epitopes; D006433:Hemocyanins; D017493:Leukocyte Common Antigens; C032808:keyhole-limpet hemocyanin