Pure Red-Cell Aplasia Associated with Clonal Expansion of Granular Lymphocytes Expressing Killer-Cell Inhibitory Receptors

Abstract
Killer-cell inhibitory receptors inhibit cytolysis when natural killer cells encounter cells bearing HLA class I molecules.1,2 This phenomenon explains the preferential killing by natural killer cells of tumor cells with reduced expression of HLA class I molecules.3 This finding is the basis of the “missing self” model, in which the HLA class I allele lost by the tumor cells is not available to inhibit the killer cell's lytic machinery.