B cell flow cytometry for common variable immunodeficiency

(Top) Left: Patterns of normal B cell differentiation in peripheral blood based on IgD and CD27. Right: Similar staining in a patient with CVID demonstrating reduced-switched memory B cells.
(Bottom) Left: Normal expression of CD21 and CD27 on B cells (cells gated on CD19). Right: Elevated CD21 low expressing CD19+ B cells in patient with CVID and splenomegaly.