Fig. 4. Exaggerated Ca²⁺ signaling in human FAD B lymphoblasts.

(A) Representative single cell Ca²⁺ responses to strong IgM stimulation (5µg/ml; arrow) in control human B lymphoblasts (CTL) or FAD lymphoblasts carrying PS1-A246E mutation. Dark lines below and to the left of each trace indicate zero Ca²⁺. (B) Responses to IgM stimulation. Percentages responding with Ca²⁺ oscillations (red) or large amplitude Ca²⁺ transients (blue). (C) Summary of peak amplitudes of high-amplitude transient Ca²⁺ responses triggered by 5 µg/ml anti-IgM. (D) Ca²⁺ oscillation frequency in response to anti-IgM. N = 3 experiments with 30 cells in each. Asterisk: p < 0.05, Student’s t-test. (E) Representative single cell Ca²⁺ responses to weak IgM stimulation (50 ng/ml; arrow) and (F) spontaneous oscillations during perfusion with serum-containing medium in lymphoblasts from unaffected (CTL) and FAD individuals. Dark lines: zero Ca²⁺ level. (G) Percentage of cells responding to IgM (black) or undergoing spontaneous Ca²⁺ oscillations in complete medium (blue). (H) Summaries of Ca²⁺ oscillation frequency in response to IgM (black) or spontaneous Ca²⁺ oscillations observed in complete medium (blue). Data in each group summarized from 4 experiments with 30 cells in each. Asterisks or #: p < 0.05 by ANOVA as compared with respective controls.