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Purpose: Radiosensitivity in relation to the human immunodeficiency virus (HIV) status is important in South Africa as the prevalence of HIV infections is high. In this study the in vitro chromosomal radiosensitivity of HIV positive individuals was investigated and compared with that of HIV negative individuals. Materials and methods: Blood samples from 59 HIV positive and 39 HIV negative individuals were exposed in vitro to doses of 6MV X-rays ranging from 1–4 Gy. Chromosomal radiosensitivity was assessed with the micronucleus assay. Micronuclei are a measure of chromosomal damage and were quantified in at least 500 binucleated lymphoblasts (BN) per sample. Un-irradiated control samples from each donor were also analysed. Results: In 47% of HIV positive individuals difficulties with cell stimulation by adding phytohaemagglutinin (PHA) to blood cultures were noticed which resulted in insufficient yield of BN for microscopic analysis. Micronuclei frequencies were consistently higher in irradiated lymphocytes obtained from HIV positive individuals compared to that observed in cells from HIV negative donors. Data for both groups were fitted to the linear-quadratic equation Y = αD + βD2 where Y is the number of micronuclei in 500 binucleated cells and D is the dose in Gy. The fitted parameters for respectively HIV positive and HIV negative lymphocytes are α = 80.17 Gy−1, β = 14 Gy−2 and α = 54.5 Gy−1, β = 16.2 Gy−2. The confidence ellipses of these parameters are separated indicating that the increase in radiosensitivity is statistically significant. Conclusion: T-lymphocytes of HIV infected individuals were considerably more sensitive to X-rays compared to that of HIV negative donors. This may have implications for normal tissue tolerance during radiotherapy as well as for the radiological health of radiation workers. [ABSTRACT FROM AUTHOR]

Cervical cancer is the second most common cancer amongst South African women and is the leading cause of cancer-associated mortality in this region. Several international studies on radiation‑induced DNA damage in lymphocytes of cervical cancer patients have remained inconclusive. Despite the high incidence of cervical cancer in South Africa, and the extensive use of radiotherapy to treat it, the chromosomal radiosensitivity of South African cervical cancer patients has not been studied to date. Since a high number of these patients are human immunodeficiency virus (HIV)‑positive, the effect of HIV infection on chromosomal radiosensitivity was also investigated. Blood samples from 35 cervical cancer patients (20 HIV‑negative and 15 HIV‑positive) and 20 healthy controls were exposed to X‑rays at doses of 6 MV of 2 and 4 Gy in vitro. Chromosomal radiosensitivity was assessed using the micronucleus (MN) assay. MN scores were obtained using the Metafer 4 platform, an automated microscopic system. Three scoring methods of the MNScore module of Metafer were applied and compared. Cervical cancer patients had higher MN values than healthy controls, with HIV‑positive patients having the highest MN values. Differences between groups were significant when using a scoring method that corrects for false positive and false negative MN. The present study suggested increased chromosomal radiosensitivity in HIV-positive South African cervical cancer patients.