My laboratory is interested in the biology of human natural killer (NK) cells and how they contribute to disease processes. NK cells are critical participants in innate immunity and have the ability to recognize and kill virally infected cells and tumor cells. Based on their ability to recognize immune molecules termed human leukocyte antigens (HLA), NK are able to discriminate between cells that are “self” from foreign or damaged cells. One family of receptors that recognize these HLA molecules are termed killer Ig-like receptors (KIR) and are found on the surface of NK cells. Interaction of the NK cell and its potential target cells through engagement of KIR and HLA molecules leads to one set of NK actions; importantly, non-engagement of KIR and HLA molecules leads to another set of NK actions. Genes encoding KIR and HLA can therefore be used to predict these actions and therefore NK behavior in certain disease states.