Étude de la Leucémogénèse akr a l'aide d'un marqueur cytogénétique

AKR‐TIALD mice bearing 38 chromosomes with 2 metacentrics are irradiated and restored with AKR (40 acrocentrics) bone marrow. These isogenic radiation chimaeras provide the opportunity to perform a cytogenetic study in order to determine the origin of the cells, the chronology of bone marrow thymus, and lymph node repopulation as well as of the leukaemic process. In AKR/TIALD chimaeras the repopulation of the lymphatic system follows the same steps as previously described in CBA/T6‐T6. The lymphatic leukaemias induced by 4 irradiations of 175 R may be divided into three groups according to their latencies: (a) Early or radiation‐induced leukaemias which may originate from either host cells or donor cells or both (mixed leukaemias), (b) the leukaemias which appear between 180 and 220 days and belong mainly to host cells, (c) late leukaemias, posterior to 220 days, the cells of which are of donor origin. Most leukaemias of host origin precede the leukaemias of donor origin because the cells of the latter must differentiate from the injected stem cells which first repopulate bone marrow into more mature elements which secondarily migrate into the thymic cortex where the lymphosarcomatous foci originate. The results of an experiment where T1ALD mice were restored with an equal number of AKR and T1ALD bone marrow cells, point to the possible multifocal origin of the leukaemia. T1ALD cells have the same sensitivity to X radiation and to Gross virus than the cells from conventional AKR mice.