Severe Herpesvirus Infections in an Adolescent without Natural Killer Cells

NATURAL killer cells are a population of T-cell–receptornegative (CD3–) lymphocytes that spontaneously mediate the lysis of sensitive target cells. Natural killer cells are similar morphologically to large granular lymphocytes.1 They have the CD16 receptor for Fc portions of immunoglobulin molecules,2 and they express a member of the complement receptor–lymphocyte adhesion family of molecules, CD11b,3 on their cell surfaces, as well as the determinant NKH-1, which is specific to large granular lymphocytes.4 Although endogenous killer cells isolated from normal persons lyse only a limited range of highly sensitive target cells, both interferon and interleukin-2 can activate killer cells to lyse a . . .