Sandwich radioimmunolabeling for the study of surface properties of bone marrow lymphocytes

A modification of sandwich radioautographic method was applied to the study of surface immunoglobulin and/or specific antigens on small lymphocytes in mouse and human bone marrow. After incubation of marrow cell suspensions at 370C, cells were reacted at 00C for 30 min with graded dilutions of rabbit anti-mouse or anti-human immunoglobulin followed by further reaction with a sheep anti-rabbit immunoglobulin labeled with 125I. Detectable surface immunoglobulin was demonstrated in approximately one-third of mouse marrow lymphocytes and 20-25% of human marrow lymphocytes. The densities of surface immunoglobulin as assessed by grain counts on individual labeled lymphocytes tended to be lower in the marrow than in spleen or peripheral blood. When the same rabbit antiserum was used to compare the sensitivity of the sandwich method with that of the direct radioautography, the former was found sufficiently sensitive to give a plateau level of labeling without seriously increasing background grains. The advantages of the method are discussed with reference to studies on T and B cell specific antigens on human bone marrow lymphocytes. (Auth.)