CSF2 and rheumatoid arthritis: Analysis of paired synovial fluid (SF) samples from patients with persistent UA (n=12), UA>RA (n=9), UA>PsA (n=7), RA (n=9) and PsA (n=9) indicated that GM-CSF levels were below detection levels in most SF samples, except for 4 out of 9 (44%) persistent UA patients who were csDMARD naïve, and one UA>PsA patient out of 7 analyzed (14%), who had increased GM-CSF levels (Figure 1C).