Autoantibody-producing RP105(-) B cells, from patients with systemic lupus erythematosus, showed more preferential expression of BCMA compared with BAFF-R than normal subjects.
OBJECTIVE
B cells lacking RP105 produce autoantibodies in patients with SLE. Expression of B-cell activating factor (BAFF) binding receptors (BBRs) and survival of RP105(-) B cells from SLE patients were examined.


METHODS
Detection of difference of gene expression between RP105(-) and RP105(+) B cells was done by DNA microarrays. Surface expression was confirmed by flow cytometry. The contribution of BAFF, a proliferation-inducing ligand (APRIL) and monomers/trimers of sCD40L to survival of RP105(-) and RP105(+) B cells was examined.


RESULTS
Gene expression of B-cell maturation antigen (BCMA) was different among BBRs in RP105(-) and RP105(+) B cells in SLE. Preferential expression of BCMA on RP105(-) B cells was confirmed compared with RP105(+) B cells by flow cytometry, although BAFF receptor (BAFF-R) expression on RP105(-) B cells was significantly lower. Additionally, relative ratios of BCMA/BAFF-R expression on RP105(-) B cells were increased significantly in SLE patients compared with normal subjects. Stimulation by sCD40L decreased the number of surviving RP105(-) and RP105(+) B cells in vitro. RP105(+) B cells were not rescued from sCD40L-induced cell death by BAFF and/or APRIL. In contrast, either BAFF or APRIL maintained the survival of RP105(-) B cells due to avoidance of cell death. Activated RP105(-) B cells reduced BAFF-R and increased BCMA levels.


CONCLUSIONS
RP105(-) B cells from SLE patients showed more preferential expression of BCMA compared with BAFF-R than normal subjects, and were possibly regulated by BAFF/APRIL. Our results provide a new insight of BCMA and their ligands in B cells from SLE patients.
Koarada
Syuichi
S
Division of Rheumatology, Saga University, 5-1-1 Nabeshima, Saga 849-8501, Japan. koarada@med.saga-u.ac.jp
Tada
Yoshifumi
Y
Sohma
Yoshiaki
Y
Haruta
Yoshio
Y
Suematsu
Rie
R
Mitamura
Mio
M
Inoue
Hisako
H
Ehara
Hiromi
H
Tokoro
Yusuke
Y
Ohta
Akihide
A
Nagasawa
Kohei
K
D000293:Adolescent; D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000276:immunology*; D053265:B-Cell Activation Factor Receptor / Q000235:genetics / Q000276:immunology*; D053301:B-Cell Maturation Antigen / Q000235:genetics / Q000276:immunology*; D016022:Case-Control Studies; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000235:genetics / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D055815:Young Adult
D001323:Autoantibodies; D053265:B-Cell Activation Factor Receptor; D053301:B-Cell Maturation Antigen