IgM Augments Complement Bactericidal Activity with Serum from a Patient with a Novel CD79a Mutation.

Area of Science:

• Immunology
• Infectious Diseases

Background:

• Antibody deficiency disorders often involve concurrent deficiencies in immunoglobulin G (IgG), immunoglobulin M (IgM), and immunoglobulin A (IgA).
• Current IgG replacement therapy does not address IgM and IgA deficiencies, leaving patients susceptible to recurrent mucosal infections, especially those with IgM deficiency.

Observation:

• A patient with agammammaglobulinemia due to CD79A deficiency developed a severe Campylobacter jejuni infection despite standard therapy.
• In vitro studies demonstrated that serum IgM is crucial for complement activation on the bacterial surface of C. jejuni.

Findings:

• Supplementation of serum with purified IgM significantly enhanced complement deposition on C. jejuni.
• Adding IgM to serum markedly increased bactericidal activity against C. jejuni in vitro.

Implications:

• Supplementing intravenous IgG therapy with IgM may offer improved protection against bacterial infections in antibody deficient patients.
• This strategy holds potential for managing infections in the face of rising antibiotic resistance.