The role of the CD19/CD21 complex in B cell processing and presentation of complement-tagged antigens.
The CD19/CD21 complex is an essential B cell coreceptor that functions synergistically to enhance signaling through the B cell Ag receptor in response to T cell-dependent, complement-tagged Ags. In this study, we use a recombinant protein containing three tandemly arranged copies of C3d and the Ag hen egg lysozyme, shown to be a highly effective immunogen in vivo, to evaluate the role of the CD19/CD21 complex in Ag processing in B cells. Evidence is provided that coengagement of the CD19/CD21 complex results in more rapid and efficient production of antigenic peptide/class II complexes as compared with B cell Ag receptor-mediated processing alone. The CD19/CD21 complex does not itself target complement-tagged Ags for processing, but rather appears to influence B cell Ag processing through its signaling function. The ability of the CD19/CD21 complex to augment processing may be an important element of the mechanism by which the CD19/CD21 complex functions to promote B cell responses to T cell-dependent complement-tagged Ags in vivo.
Cherukuri
A
A
National Institute of Allergy and Infectious Diseases, Laboratory of Immunogenetics, National Institutes of Health, Rockville, MD 20852, USA.
Cheng
P C
PC
Pierce
S K
SK
D000276:Adjuvants, Immunologic / Q000502:physiology; D000818:Animals; D017951:Antigen Presentation / Q000276:immunology*; D018941:Antigens, CD19 / Q000502:physiology*; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism*; D015933:Complement C3d / Q000378:metabolism*; D005260:Female; D000949:Histocompatibility Antigens Class II / Q000378:metabolism; D008024:Ligands; D046911:Macromolecular Substances; D008297:Male; D051379:Mice; D008808:Mice, Inbred CBA; D008822:Mice, Transgenic; D009113:Muramidase / Q000378:metabolism; D010446:Peptide Fragments / Q000276:immunology / Q000378:metabolism; D010767:Phosphorylcholine / Q000378:metabolism; D010873:Pinocytosis / Q000276:immunology; D011947:Receptors, Antigen, B-Cell / Q000276:immunology / Q000378:metabolism; D017464:Receptors, Complement 3d / Q000502:physiology*; D015398:Signal Transduction / Q000276:immunology; D014407:Tumor Cells, Cultured
D000276:Adjuvants, Immunologic; D018941:Antigens, CD19; D000949:Histocompatibility Antigens Class II; C111388:I-Ak antigen; D008024:Ligands; D046911:Macromolecular Substances; D010446:Peptide Fragments; D011947:Receptors, Antigen, B-Cell; D017464:Receptors, Complement 3d; D010767:Phosphorylcholine; D015933:Complement C3d; C421864:hen egg lysozyme; D009113:Muramidase