Defective monocyte function in pyoderma gangrenosum with IgG kappa paraproteinaemia

Area of Science:

• Immunology
• Dermatology
• Hematology

Background:

• Pyoderma gangrenosum (PG) is a rare inflammatory skin disease.
• Monoclonal gammopathy is associated with various autoimmune and inflammatory conditions.
• The pathogenesis of PG in the context of monoclonal gammopathy is not fully understood.

Observation:

• Peripheral blood monocytes from a PG patient with paraproteinemia exhibited defective phagocytosis.
• The phagocytic defect correlated with paraprotein levels and clinical activity of PG.
• Treatment with Melphalan reduced paraprotein, induced PG remission, and normalized monocyte function.

Findings:

• Recurrence of elevated paraprotein levels was associated with a return of the monocyte defect and PG.
• Normal monocytes incubated with the patient's plasma or IgG fractions showed induced phagocytic defects.
• The patient's serum displayed anti-heparin activity, prompting exploration of its role in the phagocytic defect.

Implications:

• Suggests a potential pathogenetic mechanism linking PG and monoclonal gammopathy.
• Highlights the role of specific immunoglobulin abnormalities in immune cell dysfunction.
• Provides a basis for further research into targeted therapies for PG associated with paraproteinemia.