Myeloid and erythroid lineage expression of haemopoietic progenitors derived from an abnormal clone in erythroleukaemia

Summary. To clarify the lineage involvement of haemopoietic progenitor cells in erythroleukaemia, the morphology and chromosomes of single colonies from a patient with erythroleukaemia were analysed simultaneously. The cytogenetic analysis of bone marrow cells revealed two clones; 44.XY, −7, −12, −17, del (5)(q31),+ Mar and 43,XY, −7, −12, −17, −19,del(5)(q31),+ Mar. Of 40 metaphases examined, there were 34 and six of these clones, respectively. Bone marrow mononuclear cells were plated at 5 × 10⁴/ml in methylcellulose medium containing phytohaemagglutinin‐stimulated leucocyte conditioned medium and erythropoietin. Seventeen colonies, i.e. nine blast cell colonies, four myeloid (Sudan black B‐positive) colonies, and four erythroid (benzidine‐positive) colonies contained analysable metaphases, yielding 102 metaphases in total. Except for chromosome random loss, the karyotype within a colony remained constant. All three types of colonies showed an abnormal clone; 44.XY, − 7, −12, − 17,del(5)(q31),+Mar. From these findings, it is concluded that myeloid and erythroid lineages in erythroleukaemia were derived from the same abnormal clone.