[Recognition and significance of hybrid granulocytes in chronic myeloid leukemia].

The demonstration and frequency of mixed granulated, hybrid leukocytes in chronic myeloid leukemia are reported. The cells exhibit basophilic granules, and, in addition, variable quantities of eosinophilic and/or azurophilic (chloroesterase-positive) granules. The existence of further subtypes of granules in these cells, such as neutrophilic or tissue mast cell granules, cannot be excluded thus far. All cases under investigation showed such cells, though in varying frequency. Quality and quantities of the granule population in these cells differed considerably. This is interpreted as an expression of tumor cell heterogeneity, which represents a general criterion of malignant neoplasias. The cells under discussion may be termed hybrid or chimeric, since they are characterized by the co-expression in the same cells of markers (granules) normally subject to lineage specificity. Therefore, the cells represent the phenomenon of "lineage infidelity". Thus far, "lineage infidelity" has been found only with blast cell leukemias, but applies also to chronic myeloid leukemias, as our results show. The occurrence of "lineage infidelity" in segmented end stage cells expresses grave irreversible genetic disturbances of the differentiation program in the progenitors of the hybrid leukocytes.