Figure 1.

NK cell receptor interactions with HLA class II molecules. FCRL6⁺ NK cells have been shown to interact with HLA-DR molecules. The binding of FCRL6 to HLA-DR molecules inhibits NK cell function. LAG-3 has been described to bind to HLA-II molecules and has been attributed an inhibitory function after engagement of HLA-II molecules. NKp44 has been described to bind to a subset of HLA-DP molecules and transmit activating signals after binding. Inhibitory splice isoforms of NKp44 expressed on tissue-resident NK cells or NKp44 expression on other innate immune cells might transmit inhibitory signaling after engagement of HLA-DP molecules.