Figure 5.

Application of the IgH-isotype tube for the dissection of switched memory B-cells and plasmablasts in blood from healthy donors and PID patients. (A) Bivariate plots showing the distribution of switched memory B-cells (smIgMD⁻CD19⁺CD38⁻) and plasmablasts (CD19⁺CD27⁺⁺CD38⁺⁺⁺) according to the surface membrane expression of the different IgH-isotypes (IgG1, IgG2, IgG3, IgG4, IgA1, and IgA2) in 5 × 10⁶ peripheral blood leukocytes analyzed with the IgH-isotype tubes in samples from a healthy adult. (B) Three dimensional PCA representation of IgH-isotype subsets in memory B-cells (top) and plasmablasts (lower) in a healthy adult donor (left), a selective IgA-deficient patient (middle), and a CVID patient (right). No plasmablasts were detected in blood from the CVID patient (count of <0.01 cells/μL blood), while variable defects were detected in the memory B-cell compartment, particularly involving switched memory B-cells. The defects in the IgA-deficient patient mainly concerned the IgA-class-switched plasmablasts.