PARENT SESSION

(W537) TESTICULAR ISOFORM OF ANGIOTENSIN I-CONVERTING ENZYME (ACE, CD143) ON THE SURFACE OF HUMAN SPERMATOZOA: REVELATION AND QUANTIFICATION USING MONOCLONAL ANTIBODIES.

Danilov, Sergei¹, Nikolaeva, Marina², Balyasnikova, Irina¹, Alexinskaya, Marina ^{2, 3}, Metzger, Roman⁴, Franke, Folker⁵, Albrecht, Ronald, Kulakov, Vladimir², Sukhikh, Gennady², ¹ University of Illinois, Chicago, IL² Research Center for Obstetrics, Gynecology and Perinatology, Moscow, Russia³ Lomonosov Moscow State University, Moscow, Russia⁴ Ludwig-Maximilian University, Munich, Germany⁵ Justus-Liebig University, Giessen, Germany

ABSTRACT- Testicular isoform of angiotensin-converting enzyme (ACE, CD143) expressed exclusively in spermatides and spermatozoa play an important functional role in male reproduction; male mice deficient in this isoform are nearly infertile. The expression of testicular ACE (tACE) on the surface of human spermatozoa was analyzed by flow cytometry using new monoclonal antibodies (mAbs) to human tACE. mAb 1E10 and 4E3 similarly revealed tACE on the surface of native human spermatozoa: around 60 % of live spermatozoa in the highly motile swim-up fraction of human ejaculate were tACE -positive. Flow cytometry on live spermatozoa separated from native semen by Percoll gradient centrifugation, demonstrated a higher percentage of tACE-positive spermatozoa in the fraction, which contained mainly morphologically normal, highly motile spermatozoa. In contrast, flow cytometry of methanol-fixed sperm (using mAb 1D8) revealed a higher level of tACE expression in a fraction, which contained higher percentage of abnormal spermatozoa. These data indicate that antibody-induced tACE shedding occurs preferentially from poorly motile and/or abnormal spermatozoa. Testicular ACE is located on the plasma membrane of the post-acrosomal region, the neck and midpiece of normal spermatozoa, but showed a variable distribution on defective cells. Thus, the new mAbs recognizing the C-terminal domain of human ACE are useful tools for quantification of tACE expression on live and fixed human spermatozoa and for evaluating the role of tACE in male fertility.

KEY WORDS: testicular ACE, spermatozoa, flow cytometry, immunohistochemistry