Autorosette formation in humans: study of the specificity of the T cell receptors for autologous erythrocytes.

Spontaneous autorosette formation has been described as being restricted to a subpopulation of the circulating helper/inducer T cell subset. In order to study the specificity of the binding between human lymphocytes and autologous red blood cells (auto-RBC), we have investigated the relationship between autorosette forming cells (auto-RFC) and rosettes formed with allogeneic (allo-) or xenogeneic (xeno-) RBC. Using a mixed rosette assay in which the origin of the erythrocytes was assessed by the FITC labeling of one type of erythrocyte, we have shown that auto-RFC and allo-RFC belong to the same T cell subset, and that the T cells which rosette with auto-RBC can also bind xenogeneic (pig, sheep, rabbit) RBC, although a disparate incidence of rosettes is found depending upon the origin of the erythrocytes. Whether T lymphocytes co-expressed distinct receptors for RBC of different species was then investigated. Preincubation of lymphocytes with monoclonal antibody OKT11A (directed against the T cell receptors for sheep RBC) completely abrogated rosette formation with auto- or allo-RBC, indicating that auto- and allo-RBC interact with the lymphocytes by their receptors for sheep RBC. Therefore, the auto-RFC may represent T lymphocytes having high affinity receptors for sheep RBC.