CD27 and systemic lupus erythematosus: Notably, the abundance of CD27+CD28+ and CD45RA+HLADR+ Th cells in the SLE-A group was significantly lower than that in the SLE-NA group, while the proportion of CD27−CD28−, CD45RA−HLADR−, and CD45RA−CD27− Th cells showed a significant increasing trend.