BTLA and autoimmune disease: To examine if autoimmune disease occurs when BTLA or PD-1 is deleted post-thymic selection, thymocytes from adult (7–9 week-old) B6Cre/ERT2+/− Btlafl/fl or B6Cre/ERT2+/− Pdcd1fl/fl mice were adoptively transferred via the tail vein to adult Rag−/− mice, followed by tamoxifen injection to induce gene deletion in the transferred thymocytes.