Impaired bactericidal but not fungicidal activity of polymorphonuclear neutrophils in patients with chronic...

Area of Science:

• Immunology
• Hematology
• Infectious Diseases

Background:

• Chronic lymphocytic leukemia (CLL) is a hematologic malignancy characterized by immune dysregulation.
• Polymorphonuclear neutrophils (PMNs) play a critical role in host defense against microbial pathogens.
• Understanding PMN function in CLL is crucial for managing infection risk in these patients.

Purpose of the Study:

• To investigate the phagocytic and microbicidal capacity of PMNs in non-neutropenic patients with CLL.
• To compare PMN responses against bacterial and fungal pathogens in CLL patients versus healthy controls.
• To explore potential molecular mechanisms underlying PMN dysfunction in CLL.

Main Methods:

• Collected neutrophils from 47 non-neutropenic CLL patients and healthy controls.
• Assessed phagocytic killing of Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, and Aspergillus fumigatus.
• Utilized multiplex real-time PCR to analyze gene expression of PMN receptors, soluble factors, and cytokines.

Main Results:

• CLL patients demonstrated diminished PMN microbicidal response against bacteria (S. aureus, P. aeruginosa) but not fungi (C. albicans, A. fumigatus).
• No significant differences in basal PMN pathogen-associated molecular pattern receptor or cytokine gene expression were found between patients with impaired versus effective PMN responses.
• Impaired PMN microbicidal response against A. fumigatus in CLL patients correlated with the severity of hypogammaglobulinemia.

Conclusions:

• Neutrophils in CLL patients exhibit specific functional deficits against bacterial pathogens.
• The observed PMN impairment is not explained by differences in basal PAMP receptor or cytokine gene expression.
• Hypogammaglobulinemia may contribute to impaired fungal microbicidal responses in CLL patients.