CD4 and arthritic joint disease: Our findings showed an upregulation of VPAC1 and VPAC2 in GD patients as a group, in accordance with the dynamic regulation of both receptors reported in several autoimmune diseases, such as in PBMC and T cells from early arthritis patients14,18,in monocytes from rheumatoid arthritis (RA) patients37,in CD4+ T cells from multiple sclerosis (MS) patients38, and in monocytes from Sjögren’s syndrome (SS) patients39.