SELL and neoplasm: Our findings suggest that an unexpected outcome of clinical ACT immunotherapy in patients with high MDSC burdens is that a high proportion of transferred T cells will undergo two major MDSC-mediated events that impair T cell responses in LN: (1) reduced LN homing due to rapid L-selectin loss within 24 hr, and (2) immune suppression stemming from T cell preconditioning prior to direct tumor-antigen exposure.