LAG3 and neoplasm: The dataset includes age of onset, lymphocyte count in peripheral blood, BLV proviral load, tumor cell type, the percentage of B cells in peripheral blood, and the percentages of PD-1+LAG-3+ cells, PD-1+LAG-3− cells, and PD-1−LAG-3+ cells in CD4+, CD8+, and γδTCR+ T-cell subset of seven EBL animals tested in this study.