Letter: Cytogenetic evidence of in-vivo leukaemic transformation of engrafted marrow cells

Cytogenetic analysis in human bone marrow transplantation

Chromosome and sex chromatin studies have contributed significantly to the evaluation of human bone marrow transplants. In addition to their use in documenting bone marrow engraftment following transplantation, they have been used to (1) evaluate whether recurrent leukemia occurs in donor or recipient cells and whether recovery in aplastic anemia results from growth of host or donor cells, (2) demonstrate the bone marrow origin of pulmonary macrophages and hepatic Kupffer cells, (3) show that bone marrow fibroblasts have an origin different from that of the hematopoietic bone marrow cells, (4) evaluate twin zygosity in preparation for transplantation, and (5) show that the defect in Fanconi's anemia is intracellular.

Evidence of clastogens in acute leukemia. Chromosomal abnormalities in healthy parents of congenital leukemic patients

If leukemia is caused by an "agent" which can pass through the placenta, it could produce leukemic transformation in the maternal cells. Cytogenetic studies were carried out in 5 acute lymphoblastic leukemic children and their parents. Significant abnormalities were found in 3 of the fathers, 4 of the mothers, and all the leukemic children. All but one abnormal metaphase from the mothers of the 2 leukemic boys had a XX sex pattern, indicating that these abnormal metaphases originated in the mother and probably were caused by a chromosomal breaking agent. The abnormal metaphases found in the fathers suggests that they too were exposed to this agent. Therefore, this agent must be present in the immediate environment, and this can pass from the material circulation to the fetus through the placenta and effect the fetus cells. The failure of the infant to eradicate these abnormal cells results in the phenotypical expression of clinical leukemia.

Bone marrow chromosomes in acute lymphoblastic leukaemia: a long-term study

The bone marrow chromosomes of 25 children with acute lymphoblastic leukaemia (ALL) were examined at diagnosis before treatment, during remission, and in 12 cases, also during relapse. Follow-up was for at least six years. At diagnosis, 17 patients had a major population of chromosomally abnormal cells and of these 11 had identifiable clones. The commonest abnormality was hyperdiploidy. Eight patients had predominantly normal cells, but four of these had a minor abnormal clone. In remission, some samples were completely normal but, when pooled, remission samples had a minor population of chromosomally aberrant cells which were rarely clonal. The incidence of structural abnormalities was the same in patients who ultimately relapsed and those who remained in first remission at the end of the study, but the presence of hyperdiploid cells and/or clones in remission was more frequently associated with subsequent relapse. Relapse patterns were of two kinds: in three patients there was a return of the chromosomal abnormalities seen at diagnosis; in six others, chromosomal features in relapse were distinct from those at diagnosis. It is suggested that relapse associated with distinct chromosomal features may represent malignant transformation of a previously unaffected cell line. While chromosomal abnormalities seen prior to treatment can be related to the leukaemic event alone, abnormalities seen in remission and in relapse may result partly from drug and X-ray treatment. The relative importance of treatment and other factors to chromosomal change in ALL is discussed.