Case Number CH-047

Inventors: Bruce Ames, PhD, et al.

Abstract
The invention provides a method for single-laser flow-cytometry based assays and kits to detect and measure immature reticulocytes for presence of micronuclei. 

Exposure to environmental stress such as radiation, poor nutrition or smoking, can cause chromosome breaks, the most hazardous lesion formed by radiation.  The micronucleus test is an established method to analyze in vivo chromosomal damage and has been used by many investigators to monitor DNA integrity following exposure to poor nutrition, toxicants and other stressors.  In humans, micronucleated erythrocytes are soon filtered from circulating blood by the spleen and therefore are not generally available for analysis. 

Current methods involve measuring micronuclei in an enriched peripheral-blood reticulocytes-population (Environ Mol Mutagen (2000) 36:22-31).   Using this method, micronuclei frequency in reticulocytes approximate those observed in bone marrow.  However this method includes multiple laborious steps and also requires the use of a dual-laser flow cytometers with a UV laser.  This type of flow cytometer
 is more specialized and not widely available in common laboratory settings.  Another method employs the scoring of micronucleated reticulocytes on bench top instruments (Mutat Res (2002) 515:3-14; Mutat Res (2003) 542: 77-78), however, this procedure requires long data-collection times.

Advantage
This invention enables analysis of large numbers of cells by applying single laser flow cytometer to measure micronuclei in an enriched transferrin-positive reticulocytes population.

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