SJL mice are an inbred strain of albino laboratory mice, characterized by their white fur. They serve as valuable models in various research fields due to their distinct genetic makeup and physiological responses. Their consistent genetic background allows for reproducible experiments, making them a well-established tool for understanding complex biological processes and diseases.
Origin and Development of SJL Mice
The SJL mouse strain originated at the Jackson Laboratory, developed by James Lambert in 1955. The “SJL” designation stands for Swiss Jim Lambert, reflecting its Swiss Webster lineage and the researcher. The strain was derived from three separate stocks of Swiss Webster outbred mice brought to The Jackson Laboratory between 1938 and 1943.
These initial stocks were pen-bred until 1955, when sibling inbreeding began to create the genetically uniform SJL strain. Inbreeding, which involves mating closely related individuals over many generations, produces a strain where nearly all individuals are genetically identical. This minimizes genetic variability, making SJL mice valuable for research.
Distinct Immunological Features
SJL mice have distinct immunological features. They are highly susceptible to developing spontaneous reticulum cell sarcomas, a type of lymphoma, with approximately 90% of individuals exhibiting these tumors around one year of age. These sarcomas typically appear first in the lymphatic system and spleen before spreading to other organs like the liver and thymus. Most are classified as “type B” mixed-cell tumors, resembling Hodgkin’s disease in humans.
SJL mice are also highly susceptible to induced autoimmune diseases, especially experimental autoimmune encephalomyelitis (EAE), a recognized animal model for multiple sclerosis (MS) in humans. Their immune system shows elevated levels of circulating T cells and a noted defect in developing suppressor cells after certain stimulations. These predispositions make SJL mice valuable for studying autoimmune responses and immune system regulation.
Applications in Research
SJL mice are used in research primarily for studying multiple sclerosis (MS) through the EAE model. The EAE model in SJL mice mimics the relapsing-remitting form of human MS, characterized by periods of neurological symptoms followed by remission. Immunization with myelin-specific peptides, such as PLP139-151, induces T-cell mediated demyelination in the central nervous system, mirroring aspects of the human disease.
They are also employed in lymphoma research, specifically for studying reticulum cell sarcomas given their high spontaneous incidence. The consistent development of these tumors allows researchers to investigate tumor progression, immune system interactions with cancer, and potential therapeutic strategies. Beyond MS and lymphoma, SJL mice contribute to research on other autoimmune diseases, muscular dystrophy due to a spontaneous myopathy, and retinal degeneration. Their unique genetic background, including a splice-site mutation in the Dysferlin gene, makes them a model for limb-girdle muscular dystrophy type 2B.