BTLA and neoplasm: In the immune-desert or immune-cold tumor, the number of regulatory cells entering the tumor microenvironment elevates, the secretion of immunosuppressive cytokines such as IL-8, TGF-β, VEGF elevate, and the expression of inhibitory receptors such as PD-1, CTLA-4, TIM3, LAG3, VISTA, BTLA, CD160 on T cells is enhanced.