Dose-Dependent Enhancements by Interferon-γ on Functional Responses of Neutrophils From Chronic Granulomatous Disease Patients

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Abstract
Interferon-γ (IFN-γ) is recommended as prophylaxis against infections in patients with chronic granulomatous disease (CGD). However, since the optimal dose, the dosing interval, and the mechanisms of action are not well-defined, we studied the effects on CGD neutrophil (PMN) functions ex vivo of interferon-γ (IFN-γ). Evaluations were made on oxidative capacity, measured by superoxide anion production and chemiluminescence after stimulation with f-met-leu-phe (f-MLP) or phorbol-myristate-acetate, the killing of Aspergillus fumigatus hyphae (assessed as conversion of the tetrazolium salt MTT to formazan), and on the expression of FcγRI receptor (CD64). After randomization, 9 CGD patients (4 with gp91phox, 3 with p47phox, 1 with p67phox deficiency and 1 with unspecified CGD) were given IFN-γ, either 50 or 100 μg/m2 subcutaneously on 2 consecutive days after double blinded randomization. Furthermore, one female hyperlyonized X-linked carrier with a CGD phenotype was also studied separately after IFN-γ treatment. Evaluations were made the day before and on days 1, 3, 8, and 18 after IFN-γ administration. The killing of A fumigatus hyphae, being close to zero before IFN-γ, was enhanced on day 3, being 36% higher than pretreatment values in the high-dose CGD group and 17% in the low-dose group. The expression of FcγRI on PMN increased 3.7-fold in the high-dose and 2.3-fold in the low-dose CGD group, being maximal on day 1. Oxidative functions were raised in only selected patients represented by different subtypes of CGD. The hyperlyonized carrier of X-linked CGD responded to IFN-γ with more enhanced oxidative responses and Aspergillus killing of her PMNs than the other patients. This study suggests that a higher dose of IFN-γ than currently recommended confers transient enhancements of certain PMN functions in CGD patients.

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