FLOW CYTOMETRIC METHOD FOR SIMULTANEOUS DETECTION OF LYMPHOCYTE-K562 CONJUGATES AND IMMUNOPHENOTYPING OF THE CONJUGATE FORMING CELLS

A flow cytometric method for the simultaneous quantification and immun ophenotyping of conjugates formed by human peripheral blood lymphocyte s (PBL) and K562 cells has been developed. The method uses three fluor escent probes. One of the fluorescent probes (F-18) is used for labeli ng of PBL prior to incubation with K562 cells. After incubation the ce lls are treated with monoclonal antibodies labeled with phycoerythrin and Red613, respectively. The combination of F-18 fluorescence and lig ht scattering signals enables identification and quantification of the conjugates while the fluorescence of the monoclonal antibodies provid es information about the phenotype of the conjugate forming cells. Res ults obtained using different monoclonal antibodies are presented. The highest conjugate forming capacity has been found in the CD56+ CD8+ p opulation while the CD4+CD8- population has shown the lowest capacity to form conjugates. The influence of a washing step on the conjugate f ormation is discussed. The possibility to use the method in combinatio n with a cytotoxicity assay is indicated.