CD27 and telomere syndrome: Furthermore, the correlation analysis of B cells and CD4 T cells with the IRG CD27, CD40LG, and ICOSLG in STS patients showed a significant positive correlation between the relative frequency of B cells and the gene expression levels of the IRG CD27 (Spearman r = 0.277, p = 0.0406), ICOSLG (Spearman r = 0.541, p < 0.0001), and CD40LG (Spearman r = 0.296, p = 0.0282), and the plasma levels of CD40-L (Spearman r = 0.586, p = 0.0066).