Molecular interactions of complement receptors on B lymphocytes: a CR1/CR2 complex distinct from the CR2/CD19 complex.
The complement system augments the humoral immune response to low concentrations of antigen. This effect may be partly mediated by complement receptors on the surface of B lymphocytes that bind immunogenic complexes bearing fragments of C3 and C4. We have shown by immunoprecipitation analysis that the two complement receptors expressed by B lymphocytes, complement receptor 1 (CR1) and CR2, form a detergent-sensitive complex on the surface of tonsillar B lymphocytes and on K562 erythroleukemia cells that were co-transfected with cDNAs encoding CR1 and CR2. The CR1/CR2 complex is distinct from the CR2/CD19 complex and may assist B cell activation by efficiently capturing C3b-containing immunogens and maintaining such immunogens on the B cell after CR1 and factor I-mediated cleavage to iC3b and C3dg. The complement activating immunogen may then trigger signal transduction by the CR1/CR2 complex, the CR2/CD19 complex, or membrane immunoglobulin.
Tuveson
D A
DA
Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
Ahearn
J M
JM
Matsumoto
A K
AK
Fearon
D T
DT
D018941:Antigens, CD19; D000944:Antigens, Differentiation, B-Lymphocyte / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D001402:B-Lymphocytes / Q000378:metabolism* / Q000502:physiology / Q000648:ultrastructure; D004247:DNA / Q000235:genetics; D006801:Humans; D004915:Leukemia, Erythroblastic, Acute / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D014066:Palatine Tonsil / Q000166:cytology; D011233:Precipitin Tests; D011951:Receptors, Complement / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D017463:Receptors, Complement 3b; D017464:Receptors, Complement 3d; D015398:Signal Transduction / Q000502:physiology; D014162:Transfection / Q000235:genetics
D018941:Antigens, CD19; D000944:Antigens, Differentiation, B-Lymphocyte; D011951:Receptors, Complement; D017463:Receptors, Complement 3b; D017464:Receptors, Complement 3d; D004247:DNA