Rosetting of human red blood cells to thymocytes and thymus-derived cells

Abstract

Human thymocytes bind with human red blood cells (HRBC) and neuraminidase-treated HRBC (nHRBC) forming rosettes. Peripheral blood lymphocytes and tonsillar lymphocytes bind to nHRBC but not HRBC. The conditions which lead to nHRBC rosette formation are similar to those required for rosette formation with sheep red blood cells (SRBC). The rosetting of human lymphocytes to nHRBC does not require serum but is prevented by pretreatment of the lymphocytes with sodium azide, proteolytic enzymes, 50°C for 7 min, or anti-T cell (but not anti-B cell) serum. Peripheral lymphocytes from patients with chronic lymphatic leukaemia do not rosette with either HRBC or nHRBC. Therefore, the nHRBC rosetting lymphocyte is a living T cell. It is proposed that this in vitro test may simulate an in vivo mechanism for immune surveillance.