Studies of human natural killer cells. III. Neutropenia associated with unusual characteristics of antibody-dependent and natural killer cell-mediated cytotoxicity

Abstract

A 52-year-old Caucasian man with chronic neutropenia and recurrent infections was found to have an increased proportion of peripheral T lymphocytes having Fc receptors for IgG (T(_γ). Although levels of antibody-dependent cell-mediated cytotoxicity (ADCC) and “natural” killing (NK) by unfractionated lymphocytes were similar to those of a control donor, the frequency of NK cells was markedly increased. Removal of E rosette-forming cells eliminated both NK and ADCC by the patient's peripheral blood, in marked contrast to theenhanced cytotoxicity seen with control lymphocytes. Both normal and patient ADCC and NK functions were removed by depletion of Fc receptor-bearing cells. These depletion experiments proved that all of the patient's killer cells were E rosetteforming T_γ cells, in contrast to the heterogeneous pattern of Null_γ and T_γ killer cells seen in the blood of normal donors. The homogeneity of the T_γ proliferation suggested that ADCC and NK were mediated by the same cell type, albeit acting by different mechanisms. The addition of the patient's serum and lymphocytes to chromiumlabeled normal granulocytes caused a low but significant level of cytotoxicity, indicating that the patient's neutropenia may have been caused by a similar mechanismin vivo. There was no evidence of complement-dependent serum antibody-mediated neutrophil lysis, but one serum sample taken over the course of the patient's disease agglutinated granulocytes from four of five donors tested.