[Morphological phase contrast cinematographic studies on the kinetics of bone marrow cells and blood cells in vitro. IX. Spontaneous cell hybridization in man, a contribution to the pathogenesis of leukemoid reaction]

Interactions between lymphocytes and hematopoietic progenitor cells in normal and leukemic human bone marrow (phase contrast observations)

Single cell observations of normal and of leukemic human bone marrow cells demonstrated cell-cell interactions of lymphocytes with hematopoietic progenitor cells. In all cases lymphocytes and target cells were from the same individual. Lymphocyte-target cell interactions occurred more frequently with normal committed progenitor cells and leukemic blast cells from acute myeloid leukemia than with precursor cells of the proliferative cell pool, including myeloblasts, promonocytes, erythroblasts and megakaryocytes. Both induction of mitosis and degeneration of the progenitor cells occurred after cell-cell interaction with almost the same frequency. Acute myeloid leukemic blast cells degenerated after contact with lymphocytes with the same frequency as normal progenitor cells (i. e. in 16% of cell contacts), but especially during mitosis. In contrast, normal and regenerating bone marrow progenitor cells from myeloproliferative diseases demonstrated no degeneration after cell-cell interaction with lymphocytes during mitosis. Otherwise the induction of mitoses by lymphocyte-target cell interactions was more frequently observed in normal progenitor cells than in leukemic blasts.

Premature chromosme condensation in the bone marrow of Chinese hamster after application of bleomycin in vivo

The Chinese hamster bone marrow was used as a test system in vivo to analyse the chromosome-danaging effect of bleomycin. Both chromosome and chromatid aberrations were found. Mitoses with aberrations (Ma) show a linear dose-effect relationship after a recovery time of 24 h, the same hold true for cells with micronuclei (Cm) and for mitoses with premature chromosome condensation (PCC). The dose-effect relationships for Ma, Cm and PCC run parallel to each other with Ma at the highest and PCC at the lowest level (Ma greater than Cm greater than PCC). The time-effect relationships for Ma, Cm and PCC show that after 12 h recovery time there are no PCCs but the highest frequencies of Ma and Cm indicating that most cells are in their first post-treatment mitoses or Gi-phases at this fixation time. In addition to the frequency determinations autoradiographic analysis were performed to clarigy the nature of the PCCs. The results are interpreted as follows: bleomycin induces chromosomal aberrations that in turn give rise to micronuclei by means of lagging chromatin, main and micronuclei eventually become asynchronous in their cell cycles and mitosing main nuclei induce PCC in the micronuclei.