Flow Cytometry TUNEL Standardization for Assaying Sperm DNA Fragmentation

SUSANA M. CURI; PATRICIA H. CHENLO; LUIS A. BILLORDO; PLÁCIDA BAZ; MELBA L. SARDI; JULIA I. ARIAGNO; HERBERTO REPETTO; GABRIELA R. MENDELUK; MERCEDES N. PUGLIESE

JOURNAL OF ANDROLOGY

AMER SOC ANDROLOGY, INC

Año: 2012 vol. 33 p. 1 - 1

0196-3635

We read with great interest Muratori?s paper (Muratoriet al, 2010), because we believe that terminal deoxynucleotidyl transferase?mediated dUTP nick end labeling(TUNEL) assay standardization is a matter of greatconcern and that there are certain steps that must befollowed to achieve accurate results.We agree with the authors of the paper but feel theneed to stress several important considerations. As theauthors mention in their introduction, the labeling ofDNA breaks should be carried out by nuclear stainingwith propidium iodide (PI; Muratori et al, 2008). Wehave noted in oligozoospermia samples a clear increasein the percentage of PI-negative events with forwardscatter/side scatter similar to sperm, yielding lowerresults. The upper sperm count limit that could beconsidered a threshold for this phenomenon is difficultto establish; thus, TUNEL/PI should be applied to allsamples, and reference values should be recalculated forfuture clinical use.