Human anti-F(ab')2 antibodies show preferential reactivity for F(ab')2 molecules bearing lambda light chains

Area of Science:

• Immunology
• Autoimmunity

Background:

• Autoantibodies targeting immunoglobulin fragments are implicated in systemic lupus erythematosus (SLE).
• Understanding the specificity of anti-F(ab )2 antibodies is crucial for elucidating SLE pathogenesis.

Purpose of the Study:

• To investigate the binding specificities of anti-F(ab )2 antibodies from SLE patients and healthy controls.
• To determine if anti-F(ab )2 antibody binding correlates with specific immunoglobulin features.

Main Methods:

• Preparation of F(ab )2 fragments from IgG myelomas with defined characteristics (isoelectric points, idiotypes, light chain types).
• Enzyme-linked immunosorbent assay (ELISA) and hemagglutination assays were employed to assess antibody binding.
• Analysis of binding patterns in 29 SLE patients and 12 healthy controls.

Main Results:

• Anti-F(ab )2 antibodies from both SLE patients and controls demonstrated preferential binding to F(ab )2 fragments containing lambda light chains over kappa light chains (P < 0.0001).
• No significant correlation was found between anti-F(ab )2 binding and the isoelectric points (cationic, neutral, anionic) or DNA-associated idiotypes of the myeloma F(ab )2 fragments.
• Elevated levels of anti-F(ab )2 antibodies were observed in SLE patients during remission.

Conclusions:

• Anti-F(ab )2 antibodies exhibit a specific preference for lambda light chains, irrespective of isoelectric point or idiotype.
• This preferential binding suggests a potential role for anti-F(ab )2 antibodies in SLE, particularly those targeting lambda light chains.