Serum-serum interactions in autoimmune mice

Area of Science:

• Immunology
• Mouse Models
• Autoimmunity

Background:

• MRL/l mice are a common model for studying autoimmune diseases.
• Interactions between sera from MRL/l mice have been observed.
• The nature of these interactions requires further elucidation.

Purpose of the Study:

• To characterize the interactions between sera from old, sick MRL/l mice.
• To identify the molecular components responsible for these inter-serum reactions.
• To understand the specificities of the reactive principles involved.

Main Methods:

• Analysis of immunoprecipitation reactions between MRL/l mouse sera.
• Complement fixation assays to assess immune complex formation.
• Characterization of the immunoglobulin class involved in the reactivity.

Main Results:

• A majority of MRL/l mouse sera formed visible immunoprecipitates and fixed complement when mixed.
• Mouse sera could be segregated into two sets with more frequent inter-set than intra-set interactions.
• The reactive component was identified as immunoglobulin G (IgG) in intermediate-sized complexes.
• Reactivity was confirmed to be dependent on IgG anti-IgG specificities.

Conclusions:

• Old, sick MRL/l mouse sera possess IgG anti-IgG activity.
• These findings suggest the presence of distinct IgG autoantibody specificities within the MRL/l strain.
• This autoantibody activity may contribute to the autoimmune phenotype observed in MRL/l mice.