To get a better insight into the level of circulating CD5+ B cells as related to the systemic connective tissue disease activity.
Peripheral blood CD5+CD19+ cells of patients in the remission phase of systemic lupus erythematosus (SLE) (n = 28), Sjögren's syndrome (SS) (n = 20), rheumatoid arthritis (RA) (n = 26), and 19 control healthy subjects were analyzed by 2-color flow cytometry.
In comparison to control group, the patients with SLE had a significant increase in the relative CD19+CD5+ blood cell count (p < 0.0005); this count was also different from the finding in both RA (p < 0.005) and patients with SS (p < 0.05). In contrast, the proportion of B cells expressing CD5 (within an individual B cell population) was significantly increased in all the 3 diseases compared to healthy subjects (SLE, p < 0.0001; SS, p < 0.05; and RA, p < 0.01). In the multivariate discriminant analysis, a discriminant function defined by the CD19+CD5+ subset strongly discriminated SLE, SS and RA from the control, but also SLE from both SS and RA.
Our findings demonstrated that, in relation to healthy control subjects, the blood CD5+ B subset tended to be elevated in the patients in the remission phase of systemic connective tissue diseases, particularly in SLE.