Alterations of the cell surface morphology in human T-rosetting lymphocytes. An ultrastructural study

A study of E-rosette ultrathin sections has been undertaken in an attempt to analyze changes induced during the T-lymphocyte-sheep red blood cell interaction on the rosetted lymphocyte surface architecture. The formation of nonimmune rosettes implies different types of attachment between lymphocytes and sheep red blood cells which can affect the rosetted lymphocyte surface morphology: (a) Junctions not involving morphological changes which correspond to bands or point-to-point contact sites. (b) Junctions displaying localized morphological changes, which are revealed mainly in the form of microvilli or digitations. (c) Junctions involving broad morphological changes, revealed primarily by the development of various microvilli or other more complex structures. In both cases, the alterations are found only in those areas of the lymphocyte membrane-bound sheep red blood cells. The modifications that affect the rosetted lymphocyte make the validity of the E-rosette test questionable for studies aiming at the analysis of the lymphocyte surface architecture.