The Lbw2 locus promotes autoimmune hemolytic anemia

Area of Science:

• Immunology
• Genetics
• Autoimmune Diseases

Background:

• New Zealand Black (NZB) mice spontaneously develop autoimmune hemolytic anemia (AIHA), a model for human disease.
• Previous studies linked anti-erythrocyte antibody (AEA)-promoting loci to chromosome 4, but lacked detailed analysis.

Purpose of the Study:

• To investigate the role of the Lbw2 locus on chromosome 4 in AIHA pathogenesis using congenic mice.
• To refine the genetic mapping of AIHA-associated loci.

Main Methods:

• Utilized NZB.NZW-Lbw2 congenic mice with an introgressed segment from chromosome 4.
• Analyzed autoimmune phenotypes including AEAs, splenomegaly, anti-nuclear antibodies, and B cell populations.
• Developed subinterval congenic mice to pinpoint causative subloci.

Main Results:

• Lbw2 congenic mice showed reduced AEAs and splenomegaly, but not anti-nuclear antibodies.
• Significant alterations in marginal zone B cells and peritoneal B-1a cells were observed.
• Three subloci on chromosome 4 were identified as critical for AEA production, splenomegaly, and B-1a cell expansion.

Conclusions:

• Directly demonstrated AEA-specific promoting genes on NZB chromosome 4.
• Highlighted the influence of background genes on Lbw2-related autoimmune phenotypes.
• Refined the location of genetic variants contributing to AIHA and lupus.