SLC1A5 (solute carrier family 1, member 5), known as ASCT2, is a small neutral amino acid exchanger that is upregulated in rapidly proliferating lymphocytes but also many primary human cancers. SLC1A5 is a neutral amino acid transporter belonging to the SLC1 family and localized in the plasma membrane of several body districts. Solute-linked carrier family A1 member 5 (SLC1A5), which has a high affinity to neutral amino acids, is essential for glutamine transport and amino acid metabolism in various cancers. One of SLC1A5's primary substrates is the immunomodulatory amino acid glutamine, which plays an important role in multiple key processes, such as energy supply, macromolecular synthesis, nucleotide biosynthesis, redox homeostasis, and resistance against oxidative stress. These processes are also essential to immune cells, including neutrophils, macrophages, B, and T lymphocytes.