This technology includes mouse models of TL 1A diseases, such as inflammatory bowel disease and rheumatoid arthritis, to be used as a platform for studying therapeutic agents. The TNF family cytokine TL 1A co-stimulates T-cells through Its receptor and is required for autoimmune pathology driven by diverse T-cell subsets. Blocking TL 1A in mouse models of these diseases is efficacious blocking TL 1A may be useful for therapy of diseases in which TL 1A plays a pathogenic role.