There was a significant increase in the expression of TLR9/CD3 and TLR9/CD19 in the SSc patients (44.9 ± 18.1 and 24.1 ± 9.6) compared to that in the control (1.4 ± 0.97 and 1.3 ± 0.94; p < 0.0001 for both, respectively) being higher in those with dcSSc.
These results obtained through a large cohort of European caucasian patients with SSc do not support the contribution of CD19, CD20, CD22, CD24 variants to the genetic susceptibility of SSc.
CD19 is a critical regulator of B-cell signaling thresholds, and B cells from SSc patients exhibit increased expression of CD19, a molecule that induces SSc-specific autoantibody production in transgenic mice.
We previously showed that a single nucleotide polymorphism (SNP) in CD19 promoter region was significantly associated with increased CD19 expression level and with susceptibility to SSc.
CD19 expression levels in peripheral blood B cells were significantly elevated in both naive (P = 0.0029) and memory (P = 0.0022) B cells from patients with SSc who had the -499T allele as compared with those without the -499T allele.
Remarkably, 20% increase of CD19 expression in mice spontaneously induced SSc-specific anti-DNA topoisomerase I (topo I) antibody (Ab) production, which was further augmented by 200% overexpression.