Defects in mononuclear phagocytic system (MPS) function in autoimmune MRL-lpr/lpr mice

Area of Science:

• Immunology
• Pathology
• Autoimmune Diseases

Background:

• MRL-lpr/lpr mice model systemic lupus erythematosus.
• Mononuclear phagocyte system (MPS) dysfunction is observed in human lupus patients.
• Investigating MPS function in MRL-lpr/lpr mice is crucial for understanding lupus pathogenesis.

Purpose of the Study:

• To determine if MRL-lpr/lpr mice have defects in mononuclear phagocyte system (MPS) function.
• To compare immune complex sequestration in MRL-lpr/lpr mice versus normal controls.
• To elucidate the role of the MRL strain background and lpr gene in MPS defects.

Main Methods:

• Comparison of labeled immune complex sequestration in MRL-lpr/lpr and B6D2 mice.
• Analysis of immune complex persistence in blood and liver uptake.
• Evaluation of clearance for heat-damaged red blood cells and aggregated albumin.
• Investigation of various MRL and congenic lpr strains.

Main Results:

• MRL-lpr/lpr mice showed increased immune complex levels in blood and reduced liver sequestration.
• Defects were most pronounced in older MRL-lpr/lpr mice correlating with anti-DNA antibody levels.
• MRL-lpr/lpr mice maintained normal clearance of damaged red blood cells and aggregated albumin.
• MRL-+/-/+/- and congenic lpr strains exhibited milder MPS defects.

Conclusions:

• MRL-lpr/lpr mice possess a selective defect in mononuclear phagocyte system (MPS) Fc receptor function.
• This selective defect is linked to the MRL strain background and the lpr gene.
• MRL-lpr/lpr mice serve as a valuable model for studying MPS dysfunction in immune complex deposition diseases like lupus.