CD27 and sarcoidosis: Further investigation allowed to identify that the peripheral blood memory B cell population was altered in sarcoidosis patients compared to healthy subjects due to the decreased levels of “unswitched” (IgD + CD27+) and “class-switched” (IgD − CD27+) memory B cells, whereas the levels of CD19 + CD24+++CD38+++ and CD19 + CD5 + CD27– regulatory B cells were increased (42).