MPO and B-cell chronic lymphocytic leukemia: In the early phases of treatment, neutrophils purified from ibrutinib-treated CLL patients display decreased FcγR-mediated IL-8 production and degranulation in response to opsonized E. coli, leading to reduced release of neutrophil elastase (NE), myeloperoxidase (MPO) and lactoferrin (Prezzo et al., 2019).