Phagocytes and C4 in paraproteinaemia

Area of Science:

• Immunology
• Hematology
• Clinical Medicine

Background:

• Multiple myeloma is associated with immune dysregulation and increased susceptibility to infections.
• Polymorphonuclear leucocyte (PMN) dysfunction and complement component deficiencies, particularly C4, are observed in some patients.

Purpose of the Study:

• To investigate immunological abnormalities in multiple myeloma patients.
• To determine the relationship between PMN function, C4 levels, and paraprotein type.
• To explore the impact of these defects on the inflammatory response and infection susceptibility.

Main Methods:

• Assessed PMN adherence to nylon fiber columns.
• Measured serum C4 levels.
• Performed skin window studies to evaluate inflammatory response.
• Incubated patient PMNs in normal plasma for functional correction.
• Investigated C4 binding to paraproteins and C1 activation.

Main Results:

• 16 of 26 patients showed defective PMN adherence; 14 had low C4 levels.
• Low C4 was more frequent in patients with defective PMN adherence.
• PMN defects were primarily seen in IgG myeloma patients.
• Skin window studies confirmed impaired early inflammatory response in patients with PMN defects.
• PMN adhesiveness defects were correctable with normal plasma.

Conclusions:

• Multiple myeloma patients exhibit immunological abnormalities beyond immunoglobulin deficiencies.
• Defective PMN function and low C4 levels are common in IgG myeloma and may contribute to infection risk.
• These immune defects may play a role in the pathogenesis of recurrent infections in paraproteinemia.