Phenotypes of MRL-lpr & MRL Mice

JAX® Mice Strains MRL/MpJ-Fas^lpr/J & MRL/MpJ

Stock Numbers 000485 & 000486

MRL/MpJ-Fas^lpr/J mice (MRL-lpr; Strain 000485) develop an autoimmune disease resembling systemic lupus erythematosus (SLE) due to a mutation (Fas^lpr) that promotes survival of self-reactive lymphocytes, and a strain background (MRL/MpJ;Strain 000486) predisposed to autoimmunity. Both sexes develop disease, although it is accelerated and more severe in females. Disease characteristics in MRL-lpr include:

• Lymphoproliferation by 16-18 weeks in females and 18-20 weeks in males (Table 1)
• Progressive renal failure, as indicated by urine albumin:creatinine ratios that increase with age (Table 2)
• Lymphadenopathy and skin lesions (Table 3)

Table 1 Blood counts. Submandibular blood was collected in EDTA-coated microtainers and analyzed using an Advia 2120 hematology analyzer in a longitudinal study of MRL-lpr and MRL/MpJ control mice. Values indicate the median white blood cell count (x10³cells/μL); range and sample sizes are shown in parentheses.

Table 2 Urinalysis. Urine was analyzed using a Beckman Coulter AU680 chemistry analyzer in a longitudinal study of MRL-lpr and MRL/MpJ control mice. The albumin:creatinine ratios (mg/g) were grouped by age, sex and strain into ranges (< 10, 10 -100, >100). The median values are also provided.

Table 3 Overt signs of disease. Female (F) and male (M) MRL-lpr mice were assessed weekly in a longitudinal study for the presence of enlarged lymph nodes and skin lesions. Columns indicate the percentage of mice displaying the indicated phenotype; rightmost column indicates the number of mice assessed.