The presence within single K-562 cells of erythropoietic and granulopoietic differentiation markers.

The continuous cell line K-562, derived from a patient with CML in blast crisis, was examined for markers of granulopoietic (My-1) and erythropoietic (spectrin) differentiation, using specific antibodies detected by indirect immunofluorescence. Both markers were seen, and in 10%--30% of cells, both were present in the same cells. In contrast, the continuous leukemic line HL-60 and KGI contained My-1 only. Controls consisted of colonies in culture containing both granulopoietic and erythropoietic cells (CFU-GEMM). In these, My-1 was seen only in granulopoietic cells and spectrin in erythropoietic cells. The suggestion is advanced that genes coding for differentiation markers are expressed abnormally in K-562.