Statistical analysis (Spearman correlation coefficient) showed no correlation between relative mRNA expression of FOXP3, CD28, CTLA-4, and GITR genes and concentration of TGF-β1 in all pleural effusions (p = 0.13, p = 0.32, p = 0.50, and p = 0.88, resp). This evidence concerns the gene CTLA4 and Pleural effusion.