KIR3DL2, also known as CD158k, is an inhibitory receptor expressed by natural killer (NK) cells and a subset of CD8+ T cells. It plays a role in immune regulation by binding to HLA class I molecules, specifically HLA-A3 and HLA-A11, in a peptide-dependent fashion. KIR3DL2 can also function as an innate immune receptor for delivering CpG DNA to TLR9 in NK cells, highlighting its role in both adaptive and innate immunity. This protein is primarily expressed on the cell surface, particularly in NK cells and certain T cells. It has been implicated in various diseases, particularly in the context of hematological malignancies and autoimmune diseases. Aberrant expression of KIR3DL2 has been observed in neoplastic cells in transformed mycosis fungoides and Sézary syndrome, suggesting its potential as a therapeutic target in primary cutaneous anaplastic large-cell lymphoma (pcALCL).