NEU3 and rheumatoid arthritis: In terms of improvement assessment in RA disease activity, we suggest that B-cell ST6Gal1, B-cell Neu1, monocyte Neu3, and monocyte ST3Gal1/Neu3 ratios are useful for differentiating ACR (Figure 1) and SDAI (Table 4) improvement vs. non-improvement; this further stresses their potential involvement through modulation of the α-2,6 SIA content in IgG (or IgG autoantibodies) in the pathophysiology of disease activity improvement in RA.