CD4 and systemic sclerosis: IgG4RD is a novel disease entity characterised by serum IgG4 elevation and tissue infiltration by IgG4-positive plasma cells, followed by symptoms related to multiple AIRDs including SjS and SSc.34 35 Increase of effector memory CD4+T cells, Tfh cells, and plasmablasts and decrease of naïve CD4+T cells distinguished this cluster.