CD38 and systemic lupus erythematosus: Furthermore, our study also indicated that the frequency of the CD27+CD38+ plasma B cell subset was positively correlated with the SLEDAI score (P = 0.0016, r = 0.4485; Fig. 7A) as well as the concentrations of CRP (P = 0.0219, r = 0.3372; Fig. 7B) and IgA (P = 0.0286, r = 0.3379; Fig. 7C) in the new-onset SLE patients.