Sex differences in the expression of lupus-associated miRNAs become evident after onset of lupus. (A) Real-time RT-PCR analysis of lupus-associated miRNAs expression in splenocytes. The expression level of a specific miRNA in 23-wk-old female and 30-wk-old male and female NZB/WF1 mice was shown as the relative expression level to 23-wk-old male mice. The graphs represent the means ± SEMs (n = 5 each for 23-wk-old male and female mice groups, and n = 4 each for 30-wk-old male and female mice groups). Student t test was performed (age-matched male vs female, and sex-matched 23 wks vs 30 wks). *p < 0.05 and **p <0.01. (B and C) Anti-dsDNA autoantibody ELISA. Anti-dsDNA antibody levels were monitored sequentially every 2–4 wks in individual male (dashed blue hue lines) and female (solid pink hue line) NZB/WF1 mice that were terminated at (B) 23 wks of age and (C) 30 wks of age, respectively.