Variable interactions of recipient killer cell immunoglobulin-like receptors with self and allogenic human leukocyte antigen class I ligands may influence the outcome of solid organ transplants.

Purpose Of Review: The present review summarizes the diversity of killer cell immunoglobulin-like receptors and their complex interactions with self human leukocyte antigen class I molecules that control natural killer cell function. Further, a working model has been developed illustrating the potential impact of variable killer cell immunoglobulin-like receptor-human leukocyte antigen interactions on the outcome of solid organ transplants in view of current knowledge from basic and clinical research.

Recent Findings: In addition to restraining natural killer cell function, the interaction of inhibitory receptors with cognate human leukocyte antigen class I ligands has been recently shown to set the functional threshold for natural killer cells. Therefore, the number and type of inhibitory killer cell immunoglobulin-like receptor-human leukocyte antigen class I interactions in the recipient, as well as the type of human leukocyte antigen class I ligands expressed on the allograft, can determine the degree of natural killer cell alloreactivity and have potential impact in transplant outcome.

Summary: Natural killer cells can respond to allografts. The strength of that response is likely determined by the number and type of inhibitory killer cell immunoglobulin-like receptor-human leukocyte antigen class I ligand combinations in the recipient. Understanding the interactions of these intrinsic immunogenetic factors in patients and donors could have important implications on solid organ transplantation.