G6PT-deficient neutrophils of GSD-Ib patients with varying maturation states were dysfunctional. (A) Analysis of the levels of total (CD66b⁺) and immature (CD66b⁺CD16^−/lo) neutrophils in the fixed, erythrocyte-depleted blood leukocytes by flow cytometry using CD66b and CD16 antibodies. Representative profiles from HDs and GSD-Ib and GSD-Ia patients are shown. (B) Hema-3–stained cytospins of isolated peripheral blood neutrophils. (C) Viability of freshly isolated and annexin V–depleted neutrophils. Annexin V–depleted blood neutrophils were used for respiratory burst, chemotaxis, and calcium mobilization analyses. (D) Neutrophil respiratory burst activity in response to PMA. Representative experiments are shown. (E) Neutrophil concentration-dependent chemotaxis in response to fMLP. Data represent the mean ± standard error of the mean (SEM) of 5 patients (P1, P8, P10, P12, and P14) examined in separate experiments. **P < .005. (F) Calcium mobilization in response to 10⁻⁷ M of fMLP. Representative experiments are shown. ○, HDs; ●, GSD-Ib patients; ▲, GSD-Ia patients.