Adaptive response in patients treated with 131I.

Area of Science:

• Radiobiology
• Cytogenetics
• Endocrinology

Background:

• Adaptive response, or radiation tolerance, is a phenomenon where a low dose of radiation can protect cells from subsequent higher doses.
• Investigating this response in patients undergoing radioiodine therapy for thyroid disease is crucial for understanding radiation effects.

Purpose of the Study:

• To determine if peripheral blood lymphocytes in patients treated with iodine-131 (131I) exhibit an adaptive response.
• To assess if 131I therapy acts as an in vivo adaptation dose, inducing radioresistance.

Main Methods:

• Blood samples were collected from thyroid patients before and 1 week after 131I therapy.
• In vitro irradiation with gamma-rays was performed on blood samples, and micronuclei yield in lymphocytes was quantified.
• The change in induced micronuclei after therapy compared to before was analyzed to detect adaptive response.

Main Results:

• A significant decrease in induced micronuclei (adaptive response) was observed in 8 out of 20 patients 1 week post-131I therapy.
• No significant difference was found in in vivo induced micronuclei or equivalent dose between responders and non-responders.
• Control subjects showed no significant change in micronuclei yield between sample collections.

Conclusions:

• Iodine-131 therapy can function as an in vivo adaptation dose, inducing a measurable adaptive response in peripheral blood lymphocytes.
• The observed adaptive response is characterized by reduced cytogenetic damage after in vitro challenge irradiation.
• There is substantial interindividual variability in the induction of this adaptive response among patients.