A method of identifying a compound for preventing and/or treating an autoimmune disease is described which comprises obtaining a (BTLA−/−) NKT cell from a non-human animal, contacting the (BTLA−/−) NKT cell ex vivo with a test compound, in the presence of an antigen, measuring a response of the (BTLA−/−) NKT cell to the antigen, comparing the response of the (BTLA−/−) NKT cell to the antigen with a response of a (BTLA−/−) NKT cell in control assay, and selecting the compound that reduces the response of the (BTLA−/−) NKT cell in the presence of an antigen compared to a response of a (BTLA−/−) NKT cell in the control assay. Other methods of identifying a compound for preventing and/or treating an autoimmune disease are also described.
