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

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. Different types of killer-cell inhibitory receptors have distinct specificity for HLA-A, B, C, and E antigens.1,4 In addition, some natural killer cells also possess receptors that induce lysis of . . .