mRNA Expression of cytotoxic molecules in NK and CD8+T cells. Quantitative reverse transcriptase (RT)-PCR demonstrated the relative expression of granzyme A, granzyme K, perforin and IFN-γ in NK (A) and CD8+T cells (B). In NK and CD8+T cells expression levels of GZMA, GZMK and IFN-G were decreased in CFS/ME (black bars) compared to the controls (white bars). PRF1 was however increased in CFS group. *Denotes statistical significant results (P ≤ 0.05). Data presented as mean ± SEM.