Novel roles for murine complement receptors type 1 and 2 I. Regulation of B cell survival and proliferation by CR1/2.
Innate components of the immune system, such as complement are known to have a modulatory effect on adaptive immune responses. Complement receptors are expressed by both B and T lymphocytes and play part in antigen presentation and cellular activation and adhesion events. On murine B cells type 1 and 2 complement receptors (CR1/2) are expressed and form a co-receptor complex together with CD19 and CD81. We used CR1/2 specific antibodies to assess the role these receptors might play in regulating cell cycling events of B cells. We show that a CR1/2 specific antibody fragment, 7G6 scFv can induce the proliferation of mature B cells. This effect is countermodulated by FcR crosslinkage and enhanced by BCR engagement. The proliferative effect is severely impaired in Cr2-/- animals, strengthening the involvement of CR1/2. Transitional B cells are prone to apoptotic death by selection events, yet they are rescued from apoptosis by CR1/2 crosslinkage. CR1/2 ligation by 7G6 scFv alone can induce nuclear translocation of NF-kappaB, supporting the above observations. We conclude that engagement of complement receptor 2 of B cells promotes the survival of both mature and transitional B cells. This activity supplements the previously described adjuvant effects of complement.
Molnár
Eszter
E
Department of Immunology, Loránd Eötvös University, Budapest, Hungary.
Erdei
Anna
A
Prechl
József
J
D000818:Animals; D017209:Apoptosis / Q000276:immunology; D001402:B-Lymphocytes / Q000166:cytology* / Q000276:immunology*; D049109:Cell Proliferation; D002470:Cell Survival; D002478:Cells, Cultured; D051379:Mice; D008815:Mice, Inbred Strains; D016328:NF-kappa B / Q000378:metabolism; D054448:Precursor Cells, B-Lymphoid / Q000276:immunology; D021381:Protein Transport / Q000276:immunology; D017463:Receptors, Complement 3b / Q000276:immunology*; D017464:Receptors, Complement 3d / Q000276:immunology*; D017452:Receptors, IgG / Q000276:immunology; D013154:Spleen / Q000166:cytology / Q000276:immunology
C499172:Fcgr2b protein, mouse; D016328:NF-kappa B; D017463:Receptors, Complement 3b; D017464:Receptors, Complement 3d; D017452:Receptors, IgG