Figure 7. Loss-of-function mutation in IL21R abolishes B cell responses to IL-21. (A and B) PBMCs from age-matched normal donors and three patients with loss-of-function mutations in IL21R were labeled with mAb against CD20, CD10, CD27, IgM, IgD, IgG, and IgA. (A) Memory B cells were quantified based on the frequency of CD20+ B cells that were CD10−CD27+. (B and C) The percentages of total B cells in normal donors or IL-21R–deficient patients that coexpressed IgM and IgD (B) and of memory (i.e., CD27+) B cells from normal donors and IL-21RMUT patients that expressed IgD, IgG, or IgA (C) were determined. **, P < 0.01. Each symbol in A and B represents an individual normal donor or IL-21RMUT patient; the horizontal bars represent means. The values in C represent the mean percentage ± SEM of memory B cells from four normal donors or three IL-21RMUT patients that express IgD, IgG, or IgA. (D–F) Naive or memory B cells sort-purified from normal donors or IL-21R1MUT patients were cultured with CD40L alone or CD40L/IL-21 (D and E) or CD40L/IL-4, CD40L/IL-10, or CD40L/IL-21 (F). After 5 d, the percentage of plasmablasts (i.e., CD38hiCD27hi) generated (D) and expression of PAX5, AICDA, PRDM1, and XBP1 by cultured naive B cells (F) were determined by flow cytometry or qPCR. The values in D represent the mean (±SEM) percentage of naive B cells that acquired a plasmablast phenotype in response to CD40L/IL-21 in experiments using naive B cells from three different normal donors or one IL-21RMUT patient. In the absence of IL-21 <0.5% plasmablasts were detected in these cultures. (E) The levels of secreted IgM, IgG, and IgA by naive and memory B cells from normal donors (ND) or IL-21RMUT patients (Pt) in response to stimulation with CD40L/IL-21 were determined by ELISA after 10 d. The amounts of Ig secreted by IL21RMUT memory B cells in response to CD40L/IL-21 did not differ from those induced by CD40L alone (not depicted). These data are from one of three experiments using naive B cells from five different healthy controls or two unrelated IL-21RMUT patients. The values in F represent the mean ± SEM from experiments using two to five different healthy controls or of three experiments using cells from two unrelated IL-21RMUT patients. The horizontal black lines on the graphs in F indicate a value of 1.0, which corresponds to the relative level of expression of the indicated gene in CD40L-stimulated normal naive B cells.
Figure 7.

Loss-of-function mutation in IL21R abolishes B cell responses to IL-21. (A and B) PBMCs from age-matched normal donors and three patients with loss-of-function mutations in IL21R were labeled with mAb against CD20, CD10, CD27, IgM, IgD, IgG, and IgA. (A) Memory B cells were quantified based on the frequency of CD20+ B cells that were CD10−CD27+. (B and C) The percentages of total B cells in normal donors or IL-21R–deficient patients that coexpressed IgM and IgD (B) and of memory (i.e., CD27+) B cells from normal donors and IL-21RMUT patients that expressed IgD, IgG, or IgA (C) were determined. **, P < 0.01. Each symbol in A and B represents an individual normal donor or IL-21RMUT patient; the horizontal bars represent means. The values in C represent the mean percentage ± SEM of memory B cells from four normal donors or three IL-21RMUT patients that express IgD, IgG, or IgA. (D–F) Naive or memory B cells sort-purified from normal donors or IL-21R1MUT patients were cultured with CD40L alone or CD40L/IL-21 (D and E) or CD40L/IL-4, CD40L/IL-10, or CD40L/IL-21 (F). After 5 d, the percentage of plasmablasts (i.e., CD38hiCD27hi) generated (D) and expression of PAX5, AICDA, PRDM1, and XBP1 by cultured naive B cells (F) were determined by flow cytometry or qPCR. The values in D represent the mean (±SEM) percentage of naive B cells that acquired a plasmablast phenotype in response to CD40L/IL-21 in experiments using naive B cells from three different normal donors or one IL-21RMUT patient. In the absence of IL-21 <0.5% plasmablasts were detected in these cultures. (E) The levels of secreted IgM, IgG, and IgA by naive and memory B cells from normal donors (ND) or IL-21RMUT patients (Pt) in response to stimulation with CD40L/IL-21 were determined by ELISA after 10 d. The amounts of Ig secreted by IL21RMUT memory B cells in response to CD40L/IL-21 did not differ from those induced by CD40L alone (not depicted). These data are from one of three experiments using naive B cells from five different healthy controls or two unrelated IL-21RMUT patients. The values in F represent the mean ± SEM from experiments using two to five different healthy controls or of three experiments using cells from two unrelated IL-21RMUT patients. The horizontal black lines on the graphs in F indicate a value of 1.0, which corresponds to the relative level of expression of the indicated gene in CD40L-stimulated normal naive B cells.

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