PRF1 and rheumatoid arthritis: Within 6 hours, these T lymphocytes of RA patients showed robust mRNA expression of TLR4, Granzyme B, Perforin, TNFα and IFNγ transcripts when stimulated with 5 μg/ml LPS, with only marginal expression in lymphocytes from healthy controls (Fig. 4a–e and Supplementary Fig. 3).