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Chronic myelocytic leukemia (CML) is cytogentically characterized by the Philadelphia chromosome (Ph(1)) resulting from a reciprocal translocation t(9;22)(q34;q11). The breakpoints on chromosome 22 are clustered within a limted region of 5.8 kilobase (kb), termed the breakpoint cluster region (bcr). Herein the bcr rearrangement was examined to clarify the relationship between CML and related diseases. By Southern blot analysis of DNA, the bcr rearrangements were recopnized (bcr(+)) in 52 of 54 standard Ph(1)-positive (Ph(1+)) CML and all 3 variant Ph(1+)CML［46, XX, t(9;22;13)(q34;q11;q22),46, XX, t89;22)(q21;q11) and 46, XX, t(9;22)(q34;q11),inv (9)(9q22;22q13)］. The site of breakpoint within bcr was not a prognostic factor in Ph(1+)CML. On the other hand bcr rearrangements were negative (bcr(－)) in 2 juvenile CML (JCML), 3 chronic neutrophilic leukemia (CNL), 9 chronic myelomonocytic leukemia (CMML), 8 polycythemia vera (PV), 15 essential thrombocythemia (ET) and 4 myelofibrosis (MF) patients. In 5 patients with Ph(1)-negative (Ph(1－)) CML/unclassifid chronic myeloproliferative disorders (UCMPD), 2 were bcr(+) and 3 were bcr(－), which strongly suggested the existence of Ph(1－)bcr(－)CML.

To clarify the ultrastructural and functional charcteristics of basophils in CML, the author observed the morphological changes of cells by scanning electron microscopy (SEM), and examined the density and redistribution of IgE receptors using an immuno-SEM technique. Histamine content and release of histamine from basophils upon addition of anti-IgE were also measured. Mature basophils, corresponding to types I and II in the basophilogram, had a spherical shape, while immature cells, corresponding to types III and IV, were pearshaped. Type I, II, III and IV basophils differed in the number of microvilli, more mature basophils having more microvilli than immature basophils. The mean number of bound immunolatex particles, which indicate IgE receptors, was 19.3±14.0/basophil in healthy subjects, 42.4±30.9 in bronchial asthmatic, and 3.7±6.6 in CML patients. The number of IgE receptors in the blastic phase of CML was much lower than in the chronic phase of CML. The histamine content of basophils was 0.5±0.3 pg/cell in the blastic phase of CML compared with 1.4±0.4 pg/cell in the chronic phase of CML, 1.3±0.4 pg/cell in healthy subjects and 1.4±0.4 pg/cell in bronchial asthmatic. These data indicate that immature basophils of CML have some morphological and functional defects.

The pathophysiologic role of basophils in CML has not been fully elucidated. In order to establish criteria for the early diagnosis of blastic crisis in CML and also to gain some information about the maturation of basophils in CML, the author observed light-microscopically the morphologic changes of basophils in CML using so-called basophilograms. Types I and II basophils in the basophilograms corresponded to mature basophils, whereas types III and IV corresponded mostly to immature cells (r=0.65, p