Characterization of Peripheral Blood Natural Killer (NK) Cells in Two Patients with CD16⁺ CD56^- NK Cell-Lineage Granular Lymphocyte-Proliferative Disorder

Abstract

In normal peripheral blood natural killer (NK) cells, the subset of CD16⁺ CD56⁺ cells is predominant, and that of CD16⁺ CD56^- cells is rarely present. Because we have found the expansion of CD16⁺ CD56^- NK cells in the peripheral blood of two patients with NK cell-lineage granular lymphocyte-proliferative disorders (NK-GLPD), the clinical findings and cellular characteristics of these patients were compared with those of CD16⁺ CD56⁺ NK-GLPD patients. Although CD16⁺ CD56^- and CD16⁺ CD56⁺ NK-GLPD cells were morphologically different, clinical findings and courses, and NK activity did not differ significantly. Because strong NK activity was demonstrated in CD16⁺ CD56^- NK-GLPD cells, the CD56 antigen, one of the adhesion molecules, did not seem to play a major role in NK cell-mediated cytotoxicity. The CD56 antigen is known to be more strongly expressed by immature NK cells than by mature NK cells. However, because interleukin 2-activated CD16⁺ CD56^- NK-GLPD cells rapidly expressed the CD56 antigen, the degree of CD56 antigen expression did not always correlate with the maturity of NK cells.