Open AccessEffect of long‐term belimumab treatment on b cells in systemic lupus erythematosus: Extension of a phase II, double‐blind, placebo‐controlled, dose‐ranging study
Author(s) -
Jacobi Annett M.,
Huang Weiqing,
Wang Tao,
Freimuth William,
Sanz Inaki,
Furie Richard,
Mackay Meggan,
Aranow Cynthia,
Diamond Betty,
Davidson Anne
Publication year - 2010
Publication title -
arthritis & rheumatism
Language(s) - English
Resource type - Journals
eISSN - 1529-0131
pISSN - 0004-3591
DOI - 10.1002/art.27189
Subject(s) - immunoglobulin d , belimumab , antibody , immunology , b cell activating factor , autoantibody , medicine , memory b cell , b cell , immunoglobulin m , serology , lupus erythematosus , flow cytometry , lymphocyte , immunoglobulin g
Objective To understand the effects of long‐term BLyS inhibition in human systemic lupus erythematosus (SLE). Methods Seventeen patients with SLE who were enrolled in a clinical trial of belimumab, a BLyS‐specific inhibitor, plus standard of care therapy were studied. Phenotypic analysis of lymphocytes was performed using flow cytometry. Circulating antibody‐secreting cells were enumerated using enzyme‐linked immunospot assay. Serum was analyzed by enzyme‐linked immunosorbent assay using an antibody that recognizes products of the V H 4–34 gene. Lymphocyte counts, Ig levels, and anti–double‐stranded DNA antibody levels were available as part of the clinical trial analyses. Results Samples were collected on days 0, 84, 168, 365, and 532 and after day 730. The total number of B cells started to decrease from baseline between days 84 and 168. This was due to a decrease in naive and transitional B cells. CD27+IgD+ memory B cells and plasmablasts decreased only after 532 days, whereas CD27+IgD− memory B cells were not affected, and there were no changes in T cells. Serum IgM levels began to decline between days 84 and 168, but there were no changes in serum levels of IgG, IgG anti‐DNA antibodies, or V H 4–34 antibodies during the study. SLE patients had more IgM‐, IgG‐, and autoantibody‐producing B cells than did normal controls on day 0. There was only a modest decrease in the frequency of total IgM‐producing, but not IgG‐producing, cells on days 365 and 532, consistent with the phenotypic and serologic data. Conclusion Our data confirm the dependence of newly formed B cells on BLyS for survival in humans. In contrast, memory B cells and plasma cells are less susceptible to selective BLyS inhibition.