Antilymphocyte serum produced by immunization with purified mouse thymocyte plasma membrane

A predominantly plasma membrane fraction was isolated from mouse thymocytes and characterised. Immunization of rabbits with this material yielded highly potent antilymphocyte sera as measured by prolongation of skin allograft survival. Potency was maintained after repeated boosting of the rabbits, yet the generation of irrelevant antibodies was contained. Binding of antilymphocyte sera to lymphocytes was studied by immunofluorescence using the analytical facility of a fluorescence activated cell sorter (FACS-1). The results demonstrated that these anti-membrane sera recognise antigens common to thymocytes and spleen lymphocytes, bind more to T-cells and thymocytes than to B-cells and bind more avidly than antisera raised with intact cells. It was concluded that this thymocyte plasma membrane preparation is highly effective in raising powerful antilymphocyte serum.