Human monoclonal macroglobulins with antibody activity.

Area of Science:

• Immunology
• Hematology
• Clinical Chemistry

Background:

• Monoclonal macroglobulinemia is characterized by the overproduction of monoclonal IgM. The function of these monoclonal immunoglobulins is often unclear, with some considered non-functional paraproteins.
• Understanding the antigen-binding activity of these monoclonal immunoglobulins is crucial for elucidating their role in disease pathogenesis and potential clinical manifestations.

Purpose of the Study:

• To investigate the specific antigen-binding activity of monoclonal immunoglobulins in patients with monoclonal macroglobulinemia.
• To determine the prevalence of autoantigen binding and its potential association with clinical features.

Main Methods:

• Sera from 172 patients with monoclonal macroglobulinemia were analyzed for specific antigen-binding activity.
• Assays included testing for cryoglobulins, rheumatoid factor (RF), cold agglutinins (CA), antinuclear antibodies (ANA), and binding to various autoantigens, glycolipids, and glycoproteins.

Main Results:

• 71% of patients exhibited monoclonal IgM binding to autoantigens.
• Rheumatoid factor (RF) was detected in 12.6% of samples, with a high association in mixed IgM-IgG cryoglobulins.
• IgM binding to antigens associated with polyneuropathies was observed in 12% of patients.

Conclusions:

• A significant proportion of monoclonal immunoglobulins in monoclonal macroglobulinemia possess functional antibody activity against autoantigens.
• This antigen-binding activity may contribute to the pathogenesis and clinical manifestations of the disease.
• Characterizing these binding activities offers insights into the nature of monoclonal gammopathies, suggesting they may represent functional antibodies rather than mere paraproteins.