Suppressive effect of intravenous immunoglobulin on peripheral blood neutrophil count in patients with idiopathic thrombocytopenic purpura

Neutropenia resulting from high-dose intravenous immunoglobulin in dermatological patients

BACKGROUND AND OBJECTIVES

Current guidelines recommend high-dose intravenous immunoglobulin (IVIG) as a rescue therapy to treat severe cutaneous autoimmune disorders. Data on IVIG-induced hematological adverse events are limited in dermatological patients. We assessed the incidence and clinical implications of IVIG-induced neutropenia.

PATIENTS AND METHODS

Patients who received one or several cycles of IVIG between 2014 and 2019 were retrospectively evaluated. IVIG was given according to standardized infusion protocols. Daily differential blood counts were performed. Information on clinical baseline data, dermatological diagnosis, immunosuppressive pre-treatment, and IVIG-related adverse events was retrieved from patient files.

RESULTS

Seventeen patients received 106 IVIG treatment cycles. Neutrophil counts below 1,500/μL were documented during 36 (34.0 %) cycles, and neutrophils fell below 1,000/μL in 14 (13.2 %) cases. The average drop of neutrophils from day one (pre-dose) to days 2 and 3 of IVIG therapy was statistically significant (p = 0.006, and p = 0.002, respectively) despite correction for hemodilution, and so was a slight decrease of thrombocytes (p = 0.029, and p = 0.011, respectively). Four patients developed seven episodes of bacterial infections during or immediately after IVIG therapy.

CONCLUSIONS

IVIG-induced neutropenia is frequent in dermatological patients. A risk of secondary bacterial infections cannot be excluded.

IVIG regulates the survival of human but not mouse neutrophils

Intravenous immunoglobulin (IVIG) are purified IgG preparations made from the pooled plasma from thousands of healthy donors and are being tested in preclinical mouse models. Inherent challenges, however, are the pluripotency of IVIG and its xenogeneicity in animals. IVIG can alter the viability of human neutrophils via agonistic antibodies to Fas and Siglec-9. In this study, we compared the effects of IVIG on human and mouse neutrophils using different death assays. Different commercial IVIG preparations similarly induced cytokine-dependent death in human neutrophils, whereas they had no effects on the survival of either peripheral blood or bone marrow neutrophils from C57BL/6 or BALB/c mice. F(ab’)₂ but not Fc fragments of IVIG induced death of human neutrophils, whereas neither of these IVIG fragments, nor agonistic monoclonal antibodies to human Fas or Siglec-9 affected the viability of mouse neutrophils. Pooled mouse IgG, which exhibited a different immunoprofile compared to IVIG, also had no effect on mouse cells. Together, these observations demonstrate that effects of IVIG on neutrophil survival are not adequately reflected in current mouse models, despite the key role of these cells in human inflammatory and autoimmune diseases.