TNFRSF1B and rheumatoid arthritis: Since Classical Monocytes from healthy donors had a high response to TNF and Classical Monocytes from RA patients had a low or no response, and Classical Monocytes from healthy donors and RA patients, respectively, had high and low levels of TNFR2 protein expression before incubation with TNF (Figure 3D), there might be a threshold of TNFR2 protein expression that, when crossed, activates a robust response to TNF.