Therapeutic targets for immunoregulatory antibodies. GITR glucocorticoid-induced tumor necrosis factor receptor related protein, NK cell natural killer cell, KIR killer inhibitory receptor, LAG-3 lymphocyte activation gene 3, TIM-3 T-cell immunoglobulin- and mucin-domain containing 3, CTLA-4 cytotoxic T lymphocyte antigen 4, BTLA B- and T-cell attenuator; PD-1 programmed cell death 1, PD-L1 programmed cell death 1 ligand 1