Human lymphocyte/human erythrocyte rosettes. I. Blood “H” rosettes are high‐affinity E‐rosette‐forming T lymphocytes occurring in high frequency

Human lymphocytes will rosette with human red blood cells under certain conditions (H rosettes). The work presented in this paper documents the following: (1) a reproducible short-term assay for the detection of H rosettes in proportions similar to those reported recently in the literature (25-30%); (2) technical improvements on the basic assay system demonstrating that, in fact, 40-65% of human lymphocytes form H rosettes; (3) the fact that, in normal donors, auto and allo H rosettes are formed by identical lymphocyte subpopulations; (4) that H rosettes are formed independently of the ABH, Rh and Thomsen-Freidenreich (TF) red-cell antigens on the indicator red cells; and (5) that H rosette-forming cells consist almost entirely of T lymphocytes having high-affinity receptors for sheep erythrocytes. The large difference in size between sheep and human RBC made it possible to do double rosette assays in which high- and low-affinity E-rosette-forming T cells could be visualized on the same slide. As with T lymphocytes in general, a large proportion of HRFC was found to have Fc-IgM receptors while a smaller proportion has Fc-IgG receptors. Studies done on a small group of leukemic patients supported the T-cell nature of the H rosette-forming cell.