G-banding chromosome studies of acute lymphoblastic Lewis rat leukemia (KPH-Lw-I).

Changes of karyotype in spontaneous acute lymphoblastic Lewis rat leukemia have been studied by conventional Giemsa staining method and by G- and C-banding techniques. Comparing with previously published normal findings in first passages on rats, an increasing number of breaks, gaps and fragments in the 5th and 14th passages has been proved. Chromosomal investigation performed after two-year transplantation of leukemia on syngenic animals revealed pseudodiploid karyotype of leukemic lymphoblasts with the persistence of cell line 42, XX, del 2, -7, -18, +2 mar, that remained unchanged up to the latest examination in April 1984. Remarkable stability of chromosomal changes such as del 2 and 7/18 translocation might indicate possible insertion sites of transforming (viral) agent and/or localization of putative oncogenes.