Cross-reactive antibodies have both protective and pathogenic potential

Area of Science:

• Immunology
• Autoimmunity
• Microbiology

Background:

• Immunoglobulin M (IgM) antibodies against phosphorylcholine (PC) are crucial for defense against bacterial infections like pneumococcal disease.
• The T15+ anti-PC response, encoded by the V1 gene segment, is typically dominant in BALB/c mice.
• The relationship between protective antibody responses and potential autoreactivity is not fully understood.

Purpose of the Study:

• To characterize novel IgM anti-PC antibodies from nonautoimmune mice.
• To investigate the dual reactivity (cross-reactivity with dsDNA) and functional properties of these antibodies.
• To explore the implications of these findings for immune tolerance.

Main Methods:

• Isolation and characterization of five IgM anti-PC monoclonal antibodies from BALB/c mice.
• Assessment of antibody cross-reactivity with double-stranded DNA (dsDNA).
• Evaluation of protective efficacy against Streptococcus pneumoniae infection in mice.
• Analysis of V region gene usage of the isolated antibodies.

Main Results:

• All five antibodies exhibited cross-reactivity with dsDNA.
• Three of the antibodies demonstrated protection against lethal pneumococcal infection.
• All five antibodies deposited in the glomeruli and induced renal dysfunction.
• None of the antibodies utilized the dominant V1 gene segment associated with the T15+ anti-PC response.

Conclusions:

• Noncanonical anti-PC antibodies can possess both protective and pathogenic autoreactive properties.
• The findings suggest that restricted immune responses may prevent the development of antibodies that target both foreign and self-antigens.
• This restriction mechanism could be vital for maintaining self-tolerance and preventing autoimmune diseases.