P IX.21 Occupational exposure to low and elevated doses of Ionizing radiation Induce an adaptive response In human lymphocyte cultures

Habit, Ola El; Sharaf, Abla; Roushdy, H.M.; Saber, Hany

doi:10.1016/s0027-5107(97)82826-6

Cited by 1 publication

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“…The adaptive response phenomenon in vivo has been observed using animal models (reviewed in refs. 3,17 and44, 45, 46, 47) as well as in lymphocytes from individuals exposed to low doses of ionizing radiation 10, 23, 24, 25, 26, 48. However, it can be misleading to evaluate adaptation in vivo without assessing the duration of the phenomenon, since it can be transient.…”

Section: Discussionmentioning

confidence: 99%

Possible transient adaptive response to mitomycin C in peripheral lymphocytes from thyroid cancer patients after iodine‐131 therapy

Gil

Oliveira

Rodrigues

et al. 2002

Intl Journal of Cancer

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Our study attempted to assess the possible induction and persistence of an adaptive response in lymphocytes of thyroidectomized thyroid cancer patients treated with 131 I (2,590 MBq, corresponding to whole body doses in the range of 200 -300 mGy), to a testing dose of mitomycin C (MMC) in vitro. The cytogenetic endpoint studied was the induction of micronuclei in cytokinesis-blocked peripheral blood lymphocytes, immediately before treatment and 1, 6 and 24 months after therapy. One month after therapy, induction of micronucleated cytokinesis-blocked lymphocytes (‰) by MMC was lower (34.6 ؎ 7.7) than before therapy (52.1 ؎ 5.0). In 7 of 11 patients this reduction was significant. However, at 6 months, induction of micronuclei was markedly higher (133.1 ؎ 13.6). This significant increase was observed regardless of the decrease at 1 month. At 24 months, the frequency of micronucleated cells decreased (84.8 ؎ 5.5), but remained higher than before treatment. The results obtained 1 month after therapy could reflect adaptation due to radiation, or a higher rate of early apoptosis or cell death, with bone marrow suppression, visible as a lower response in vitro towards MMC. At 6 months, recovery of the lymphocyte population may occur, and higher responses to MMC in vitro could reflect higher chromosomal instability in the previously irradiated stem cells with a concomitant disappearance of adaptation, whereas at 24 months the results show a tendency to return to pretherapy values.

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