CD27 and pulmonary fibrosis: Percentages of CD38+ memory CD27− B-cells, IgA+ memory CD27+ B-cells, IgM+ and IgD+ B-cells, and CD39+ T helper cells were significantly higher whereas CD39− T helper cells were significantly lower in patients with either FPF or HPS pulmonary fibrosis compared with URels (Figures 4A,B).