[Methods for the separation of lymphocytes].

The paper reviews the currently available methods for lymphocyte separation, with particular reference to their effectiveness. Procedures based on density and size, such as density gradient centrifugation and sedimentation and size filtration on columns, allow accumulation of lymphocytes of different degree of differentiation, but do not permit any quantitative separation of distinct lymphocyte populations, because density and size of cells are properties strongly varying with the degree of development and physiological state of the cells. Differences of the cells' net potential cause differential adhesion of lymphoid cells to glass or other materials, and lead to varying migration speeds in the electric field. Adherence columns afford only partial separation of T and B cells, whereas favourable results have been obtained by preparative cell electrophoresis. Special membrane structures, such as differentiation antigens including membrane-bound immunoglobulins, cell receptors and transplantation antigens make possible a specific separation of lymphocytes. Essentially, the following 5 methods are being used: 1. Cytolytic treatment of the cells with antisera against differentiation antigens in the presence of complement. 2. Rosette separation 2.1 Rosette formation with sheep erythrocytes (SE) or with antigen-coaded SE for the isolation of antigen-binding lymphocytes. 2.2 Rosette formation by antigen-antibody-complement complexes (B rosettes) 2.3 Rosette formation with SE by human T lymphocytes (T rosettes) 2.1--2.3. Separation of the rosettes from the free lymphocytes by centrifugation or sedimentation.