Primary Sjögren’s syndrome (pSS), characterized by lymphocytic infiltration of exocrine glands, anti-Ro/La autoantibody production, and hypergammaglobulinaemia, is of unknown pathogenesis, although it is attributed to reactive T cells, with a decrease in CD27+ memory B cells and an increase in circulating naïve CD27− B cells. This evidence concerns the gene CD27 and Sjogren syndrome.