Technical Report No. 14-88
Molecular analyses of in vivo HPRT mutant T cells from atomic bomb survivors
Hakoda M, Hirai Y, Kyoizumi S, Akiyama MEditor’s note: A publication based on this report was published in Environ Mutagen 13:25-33, 1989.
Summary
In vivo-derived hypoxanthine guanine phosphoribosyltransferase (HPRT)-deficient mutant T cells isolated from three nonirradiated controls and from two atomic bomb survivors were studied by Southern blot analysis to investigate the molecular spectra of the mutations. Mutant frequencies (Mf) for the three controls were 1.8, 2.3, and 7.3 x 10-6 and those for the two survivors (estimated radiation doses, DS86 kerma, were 2.46 and 2.15 Gy) were 9.3 and 14.4 x 10-6, respectively. Of the 105 mutant T cell colonies from the controls, 14 (13%) showed various structural changes in the HPRT gene. The frequency of HPRT gene structural change in one survivor with a Mf of 9.3 x 10-6 was 26% (16/61), which was significantly higher than that of the controls. However, the frequency of structural changes in the other survivor (14%, 8/59) was not higher than that of the controls. Five sets of mutants consisting of from two to six colonies had the same HPRT alterations. Of these sets, three had the same rearrangements of T cell receptor (TcR) beta and gamma chain genes, indicating a clonal expansion from one progenitor mutant. All three of these sets (in total, 10 colonies) were observed in the survivor who showed a significantly higher frequency of gross alterations than the controls. One survivor thus gave results suggesting a different molecular spectra of in vivo mutations from that of the nonirradiated controls, but the other did not. The other two sets of colonies (one in a control and the other in the second survivor) sharing HPRT changes had different TcR rearrangements indicating the mutations occurred in stem cells before the rearrangement of the TcR genes.
In vivo-derived hypoxanthine guanine phosphoribosyltransferase (HPRT)-deficient mutant T cells isolated from three nonirradiated controls and from two atomic bomb survivors were studied by Southern blot analysis to investigate the molecular spectra of the mutations. Mutant frequencies (Mf) for the three controls were 1.8, 2.3, and 7.3 x 10-6 and those for the two survivors (estimated radiation doses, DS86 kerma, were 2.46 and 2.15 Gy) were 9.3 and 14.4 x 10-6, respectively. Of the 105 mutant T cell colonies from the controls, 14 (13%) showed various structural changes in the HPRT gene. The frequency of HPRT gene structural change in one survivor with a Mf of 9.3 x 10-6 was 26% (16/61), which was significantly higher than that of the controls. However, the frequency of structural changes in the other survivor (14%, 8/59) was not higher than that of the controls. Five sets of mutants consisting of from two to six colonies had the same HPRT alterations. Of these sets, three had the same rearrangements of T cell receptor (TcR) beta and gamma chain genes, indicating a clonal expansion from one progenitor mutant. All three of these sets (in total, 10 colonies) were observed in the survivor who showed a significantly higher frequency of gross alterations than the controls. One survivor thus gave results suggesting a different molecular spectra of in vivo mutations from that of the nonirradiated controls, but the other did not. The other two sets of colonies (one in a control and the other in the second survivor) sharing HPRT changes had different TcR rearrangements indicating the mutations occurred in stem cells before the rearrangement of the TcR genes.