A distinct lymphocyte subset displaying spontaneous cytotoxic activity against chicken erythrocytes. Morphological, cytochemical, immunocytochemical and functional characterization

Abstract

Spontaneous cytotoxic activity of peripheral blood lymphocytes directed against chicken red blood cells has been studied in 12 healthy adults by photometric measurement of the hemoglobin released from the targets. Lymphocytes forming rosettes with chicken red blood cells (ChRBC-rosette positive lymphocytes) were separated from ChRBC-rosette negative cells by Ficoll gradient centrifugation. Isolated ChRBC-rosette positive cells were characterized as small lymphocytes with a dot like (focal) cytoplasmic acid hydrolase enzyme reaction and expression of CD 4 (helper-T-cell), CD 11b (monocyte) and CD 16 (natural killer cell) immunophenotype. In the second part of our work the spontaneous cytotoxic activity against ChRBCs of adherent cells, sheep red blood cell (SRBC) rosette negative and positive cells. IgG-Fc-receptor negative and positive lymphocyte subsets was studied simultaneously using monoclonal antibody markers and detecting immunoglobulin production and IgG-Fc-receptor positive cells ("suppressor-T-lymphocytes") had the highest ChRBC-cytotoxic-activity in parallel with their Leu 11b (CD 16) NK-cell marker positivity. The "suppressor-T-lymphocytes" and also the isolated ChRBC-rosette positive cells showed a suppressor effect on immunoglobulin production in co-cultures. ChRBC-rosette positive cells expressed significant natural killer activity against K-562 targets, but not a killer activity in ADCC assay. It needs further examinations to determine the functional role and the origin of ChRBC-cytotoxic cells with these unique immunophenotype and functional characteristics.