Function and specificity of human natural killer cell receptors

Area of Science:

• Immunology
• Cellular Biology

Background:

• Natural killer (NK) lymphocytes play a crucial role in the innate immune system.
• NK cells express inhibitory receptors that recognize Human Leukocyte Antigen (HLA) class I molecules, a key mechanism for self-tolerance.
• These receptors are categorized into two main families: the Immunoglobulin (Ig) superfamily and the CD94/NKG2A complex.

Purpose of the Study:

• To elucidate the diversity and function of HLA class I-specific receptors on human natural killer lymphocytes.
• To differentiate between inhibitory and activating receptor families and their roles in NK cell-mediated cytotoxicity.

Main Methods:

• Analysis of molecular families of NK cell receptors.
• Characterization of HLA class I-specific inhibitory and activating receptors.
• Investigation of receptor specificity for classical and non-classical HLA class I molecules, including HLA-G.

Main Results:

• Human NK cells express at least two families of HLA class I-specific inhibitory receptors: Ig superfamily members and the CD94/NKG2A complex.
• The CD94/NKG2A complex recognizes a broad range of HLA class I molecules, including non-classical HLA-G.
• Activating receptors include HLA class I-specific types and non-MHC specific receptors involved in targeting HLA-negative cells, with their activity regulated by inhibitory receptors.

Conclusions:

• NK cell receptor repertoire includes diverse inhibitory and activating receptors with distinct specificities for HLA class I molecules.
• The interplay between inhibitory and activating receptors regulates NK cell function, particularly in distinguishing self from non-self or altered-self targets.
• Understanding these receptor interactions is vital for comprehending immune surveillance and developing immunotherapies.