Scanning Electron Microscopy of Human T-Cell and B-Cell Rosettes

Abstract The surface of human lymphocytes was studied by scanning electron microscopy. Lymphocytes from peripheral blood or tonsils were identified as thymus-derived (T) cells or thymus-independent (B) cells by virtue of the ability of T cells to form rosettes with sheep red cells and for some B cells to form rosettes with complement-coated human red blood cells. The rosettes were gluteraldehyde fixed and subsequently examined by scanning electron microscopy. Lymphocytes, both rosetting and non-rosetting, had multiple surface microvilli. As compared to rosetting B cells, rosetting T cells were generally smaller and smoother, with fewer and shorter microvilli. Microvilli appeared to be the sole cell-cell contact point between T cells and sheep red blood cells; B cells made contact through both villous and non-villous areas. Microvilli are an important mode of primary contact between lymphocytes and the outside world. (N Engl J Med 289:548–551, 1973)