Phagocytic function of polymorphonuclear leukocytes in essential mixed cryoglobulinaemia

Area of Science:

• Immunology
• Hematology
• Cell Biology

Background:

• Essential mixed cryoglobulinaemia (EMC) is a condition characterized by abnormal proteins in the blood.
• The role of neutrophil phagocytic function in EMC pathogenesis is not fully understood.

Purpose of the Study:

• To investigate the phagocytic capacity of polymorphonuclear leukocytes (PMNs) in patients with EMC.
• To elucidate the nature of any observed defects in PMN function.

Main Methods:

• Phagocytosis assays using Candida albicans, IgG-coated sheep red blood cells, and latex particles.
• Testing with autologous serum, normal AB serum, and in serum-free conditions.
• Comparison of PMN function between 16 EMC patients and 16 healthy controls.

Main Results:

• PMNs from EMC patients demonstrated subnormal in vitro phagocytosis of Candida albicans compared to controls (p < 0.002).
• The phagocytic defect was cellular, not serum-dependent, as patient serum did not impair normal PMNs, and normal serum did not correct the defect.
• Conversely, EMC patient PMNs showed significantly enhanced ingestion of IgG-coated sheep red blood cells in serum-free medium (p < 0.002).
• No differences in latex uptake were observed between patients and controls.

Conclusions:

• PMNs in essential mixed cryoglobulinaemia exhibit a dual functional defect: impaired Candida albicans phagocytosis and enhanced IgG-coated target cell ingestion.
• These findings suggest a complex cellular abnormality in neutrophils associated with EMC.
• The contradictory results highlight the need for further investigation into the underlying mechanisms.