For instance, IgG levels in SS patients and seropositive patients with early RA (i.e. positive for ACPA and/or RA) are correlated with the ratio of CD56bright to CD56dim NK cells, where the reduction in the circulating CD56dim NK cells contributes to accumulation of these cells into glands (and joints in the case of RA), enhancing focal immune injury and eventually systemic inflammation through secretion of pro-inflammatory cytokines (e.g. IFN-γ and TNF-α) [174–176]. Here, PRTN3 is linked to rheumatoid arthritis.