Response to ODN-CpG by B Cells from patients with systemic lupus erythematosus correlates with disease activity

Different immunological alterations may condition systemic lupus erythematosus (SLE) activity. However, it is not known whether alterations in the phenotype of circulating antigen-presenting cells (APCs) and in the response to CpG oligodeoxynucleotides (ODN-CpG) correlate with disease activity. APC expression of HLA-DR, costimulatory molecules, and TLR9 expression was determined in patients with SLE, other autoimmune diseases, and healthy controls. Monocyte and B cell response to synthetic ODN-CpG sequences was also evaluated. Monocytes from patients with moderate SLE activity had higher expression of CD40 and CD86. Decreased numbers of CD19+CD80+ and BDCA-3+CD40+ cells were found in patients with severe SLE activity. In patients with moderate SLE activity, non-adherent and enriched B cell response to ODN-CpG was similar to healthy controls. Adherent and enriched B cells from patients with severe SLE activity did not increase costimulatory molecule expression or cytokine production after ODN-CpG stimulation. APCs from patients with SLE, regardless of disease activity, displayed higher percentage of TLR9+ cells, as well as increased expression of TLR9, compared to healthy controls. Results suggest that the B cell response to ODN-CpG correlates with the SLE activity, independently of TLR9 expression, indicating that alterations in B cell response in severe activity SLE may be caused by events down-stream to TLR9.