BTLA and neoplasm: For luminescence evaluation of in vitro tumor killing abilities of splenocytes, splenocytes harvested from the tumor-bearing mice undergoing chemotherapy were incubated with/without anti-BTLA Ab and then co-cultured with the irradiated WF-3/Luc tumor cells at various ratios (WF-3/Luc:splenocyte = 1:100, 1:50, 1:10, and WF-3/Luc only) (Fig. 2e1).