title: Chromosomal radiosensitivity of HIV positive individuals.
abstract: OBJECTIVE
  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.
  
  
  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 = alphaD + betaD(2) 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 alpha = 80.17 Gy(-1), beta = 14 Gy(-2) and alpha = 54.5 Gy(-1), beta = 16.2 Gy(-2). The confidence ellipses of these parameters are separated indicating that the increase in radiosensitivity is statistically significant.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Radiation Biophysics, iThemba LABS, Somerset West, South Africa. ansbaeyens@hotmail.com
authors.forename: Ans
authors.initials: A
authors.lastname: Baeyens
authors.forename: Jacobus P
authors.initials: JP
authors.lastname: Slabbert
authors.forename: Pascale
authors.initials: P
authors.lastname: Willem
authors.forename: Sibusiso
authors.initials: S
authors.lastname: Jozela
authors.forename: Debby
authors.initials: D
authors.lastname: Van Der Merwe
authors.forename: Anne
authors.initials: A
authors.lastname: Vral
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D002877:Chromosomes, Human / Q000235:genetics* / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005434:Flow Cytometry; D018023:HIV Seronegativity / Q000235:genetics / Q000528:radiation effects; D006679:HIV Seropositivity / Q000097:blood / Q000235:genetics* / Q000473:pathology*; D006801:Humans; D008214:Lymphocytes / Q000166:cytology / Q000528:radiation effects; D008297:Male; D048629:Micronuclei, Chromosome-Defective / Q000528:radiation effects; D015162:Micronucleus Tests; D008875:Middle Aged; D011836:Radiation Tolerance / Q000528:radiation effects*; D013019:South Africa; D014965:X-Rays / Q000009:adverse effects*; D055815:Young Adult