Human thymus cells: a study of rosette-forming capacity with unsensitized and sensitized erythrocytes of various species.

Human thymus cells from 117 donors aged 2 months to 15 years, were studied for rosette-forming capacity with unsensitized and sensitized erythrocytes of various species. Viability of the thymus cells at the completion of isolation ranged from 95 to 99%. Over 90% of the total population of thymus cells were identified as T lymphocytes by either standard Es-rosette assay utilizing a 4 degree incubation with preceding centrifugation or T--LCL assay, on the average. Gravity Es-rosette assay high affinity Es-rosette assay, stable Es-rosette assay or active Es-rosette assay for identification of subsets of T lymphocytes indicate that most of the human thymus cells were capable of forming rosettes with unsensitized sheep erythrocytes at higher degrees of temperature with or without preceding centrifugation. Approximately half of the human thymus cells were also capable of forming rosettes with unsensitized allogeneic erythrocytes. Less than 3% of the thymus cells expressed receptors for the Fc portion of IgG (T gamma suppressor cells) whereas less than 1% of thymus cells expressed receptors for the Fc portion of IgM (T mu helper cells), indicating that most of the thymus cells are non-T mu/non T gamma cells. Only 1% or less of the thymus cells were identified as B cells by the SIg assay, the Em-rosette assay or the Ia-like antigen assay. There was no significant difference of any rosette assay between males and females or among various age groups.