CD70, a B cell costimulatory molecule that interacts with CD27 during B-T cell contact, is overexpressed due to demethylation of its promoter regulatory elements in CD4+ T cells from patients with the following autoimmune diseases, namely systemic lupus erythematosus (SLE), subacute cutaneous lupus erythematosus (SCLE) and primary Sjögren's syndrome (pSS).
Finally, compared with controls, peripheral reduction but glandular accumulation of CXCR4+,CXCR5+,CD27+ memory B cells was identified in patients with primary SS.
Detection of multiple Ig heavy-chain transcripts in peripheral CD19+,CD27+ memory B cells of patients with SS may represent the abnormal retention of pre-switch mRNA transcripts in circulating post-switch B cells.
Abnormal B cell differentiation in primary Sjögren's syndrome results in a depressed percentage of circulating memory B cells and elevated levels of soluble CD27 that correlate with Serum IgG concentration.