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Predictive Value of Total Acrosin Activity
Letters-to-the-editor Paul G. McDonough, M.D., Associate Editor
FERTILITY AND STERILITY Copyright
(<:
1994 The American Fertility Society
Predictive Value of Total Acrosin Activity
To the Editor: We read with interest the paper by Sharma et al. (1) and conclude with them the importance of aerosin activity measurement for assessing the fertilization potential of a semen sample. However, in review of the manuscript several questions arose. First, the values for acrosin activity (approximately 1,000 ~IU /106 sperm) far exceed previously published data, e.g., De Jonge et al. (2) (approximately 20 ~IU/106 sperm), Blackwell et al. (3) (approximately 30 ~IU /106 sperm) and including the benchmark paper by Kennedy et al. (4) (approximately 25 ~IU/106 sperm). It is important for the authors to discuss their results in light of these previous data. Second, the authors do not mention in the materials and methods: [1] the number of sperm layered over Ficoll (Sigma Chemical Co., Poole, United Kingdom); [2] the number obtained post-Ficoll processing; [3] the number of sperm obtained after swim-up; or [4] after Percoll (Pharmacia, Milton Keynes, United Kingdom) separation. These are important factors for accurately calculating acrosin activity. For example, the absorbance values corresponding to an acrosin activity of 35 ~IU would be approximately 0.3 for 4 X 106 spermatozoa. When using the clinical acrosin assay, it is recommended that sperm numbers fall between 2 and 10 X 106 cells (4); this ensures that absorbance measurements will fall within the operating standards for the spectrophotometer (absorbance measurements beyond 1.0 depart from linearity and impart less precise results). However, since Sharma et al. (1) did not report the sperm numbers used for the clinical acrosin assay, it can only be reasoned from the acrosin activity data that the absorbance measurements exceeded 1.0 and/or that sperm number in the assay was much greater than 10 X 106 • The authors use "~IU/106 motile spermatozoa" in the Table titles for acrosin activity. It needs to be clarified that [1] Ficoll does not select for a motile sperm population, and as such immotile and degenerate spermatozoa contribute to the overall acrosin activity; [2] Percoll and swim-up, while selecting for a motile population, do not routinely yield a 100% motile sperm population, and therefore the
Vol. 62, No.3, September 1994
Vol. 62, No.3, September !994 Printed on acid-free paper in U. S. A.
same consideration must be given as mentioned in the previous statement. Lastly, the authors report that swim-up does not yield a sperm population with enhanced acrosin activity. These data are contrary to published reports, e.g., Kennedy et al. (4) and Tummon et al. (5). Furthermore, recent unpublished data from our laboratory suggest that Percoll processing yields a sperm population with significantly higher acrosin activity. It can be argued that by using techniques to enhance sperm quality, e.g., motility and morphology, that acrosin activity would also increase, particularly as it relates to morphology. In conclusion, we agree with the authors that measurement of acrosin activity is a good indicator for IVF success. However, the data reported by the authors needs to be questioned relative to data presented in numerous previously published reports using the same methodology.
Christopher J. DeJonge, Ph.D. Stanley G. Harris, B.S. Department of Obstetrics and Gynecology University of Nebraska Medical Center Omaha, Nebraska December 21, 1993 REFERENCES 1. Sharma R, Hogg J, Bromham DR. Is spermatozoan acrosin a predictor of fertilization and embryo quality in the human? Fertil Steril1993;60:881-7. 2. De Jonge CJ, Tarchala SM, Rawlins RG, Binor Z, Radwanska E. Acrosin activity in human spermatozoa in relation to semen quality and in-vitro fertilization. Hum Repro 1993;8:253-7. 3. Blackwell J, Kaminski JM, Bielfeld P, Mack SR, Zaneveld LJD. Human sperm acrosin. Further studies with the clinical assay and activity in a group of presumably fertile men. J Androl1992;13:571-8. 4. Kennedy WP, Kaminski JM, Vander Ven HH, Jeyendran RS, Reid DS, Blackwell J, et al. A simple, clinical assay to evaluate the acrosin activity of human spermatozoa. JAndrol1989;10:221-31. 5. Tummon IS, Yuzpe AA, Daniel SAJ, Deutsch A. Total aerosin activity correlates with fertility potential after fertilization in vitro. Fertil Steril 1991;56:933-8.
The author elected not to respond. Paul G. McDonough, M.D., Editor, Letters
Letters-to-the-editor
657
FERTILITY AND STERILITY Copyright
(<:
1994 The American Fertility Society
Predictive Value of Total Acrosin Activity
To the Editor: We read with interest the paper by Sharma et al. (1) and conclude with them the importance of aerosin activity measurement for assessing the fertilization potential of a semen sample. However, in review of the manuscript several questions arose. First, the values for acrosin activity (approximately 1,000 ~IU /106 sperm) far exceed previously published data, e.g., De Jonge et al. (2) (approximately 20 ~IU/106 sperm), Blackwell et al. (3) (approximately 30 ~IU /106 sperm) and including the benchmark paper by Kennedy et al. (4) (approximately 25 ~IU/106 sperm). It is important for the authors to discuss their results in light of these previous data. Second, the authors do not mention in the materials and methods: [1] the number of sperm layered over Ficoll (Sigma Chemical Co., Poole, United Kingdom); [2] the number obtained post-Ficoll processing; [3] the number of sperm obtained after swim-up; or [4] after Percoll (Pharmacia, Milton Keynes, United Kingdom) separation. These are important factors for accurately calculating acrosin activity. For example, the absorbance values corresponding to an acrosin activity of 35 ~IU would be approximately 0.3 for 4 X 106 spermatozoa. When using the clinical acrosin assay, it is recommended that sperm numbers fall between 2 and 10 X 106 cells (4); this ensures that absorbance measurements will fall within the operating standards for the spectrophotometer (absorbance measurements beyond 1.0 depart from linearity and impart less precise results). However, since Sharma et al. (1) did not report the sperm numbers used for the clinical acrosin assay, it can only be reasoned from the acrosin activity data that the absorbance measurements exceeded 1.0 and/or that sperm number in the assay was much greater than 10 X 106 • The authors use "~IU/106 motile spermatozoa" in the Table titles for acrosin activity. It needs to be clarified that [1] Ficoll does not select for a motile sperm population, and as such immotile and degenerate spermatozoa contribute to the overall acrosin activity; [2] Percoll and swim-up, while selecting for a motile population, do not routinely yield a 100% motile sperm population, and therefore the
Vol. 62, No.3, September 1994
Vol. 62, No.3, September !994 Printed on acid-free paper in U. S. A.
same consideration must be given as mentioned in the previous statement. Lastly, the authors report that swim-up does not yield a sperm population with enhanced acrosin activity. These data are contrary to published reports, e.g., Kennedy et al. (4) and Tummon et al. (5). Furthermore, recent unpublished data from our laboratory suggest that Percoll processing yields a sperm population with significantly higher acrosin activity. It can be argued that by using techniques to enhance sperm quality, e.g., motility and morphology, that acrosin activity would also increase, particularly as it relates to morphology. In conclusion, we agree with the authors that measurement of acrosin activity is a good indicator for IVF success. However, the data reported by the authors needs to be questioned relative to data presented in numerous previously published reports using the same methodology.
Christopher J. DeJonge, Ph.D. Stanley G. Harris, B.S. Department of Obstetrics and Gynecology University of Nebraska Medical Center Omaha, Nebraska December 21, 1993 REFERENCES 1. Sharma R, Hogg J, Bromham DR. Is spermatozoan acrosin a predictor of fertilization and embryo quality in the human? Fertil Steril1993;60:881-7. 2. De Jonge CJ, Tarchala SM, Rawlins RG, Binor Z, Radwanska E. Acrosin activity in human spermatozoa in relation to semen quality and in-vitro fertilization. Hum Repro 1993;8:253-7. 3. Blackwell J, Kaminski JM, Bielfeld P, Mack SR, Zaneveld LJD. Human sperm acrosin. Further studies with the clinical assay and activity in a group of presumably fertile men. J Androl1992;13:571-8. 4. Kennedy WP, Kaminski JM, Vander Ven HH, Jeyendran RS, Reid DS, Blackwell J, et al. A simple, clinical assay to evaluate the acrosin activity of human spermatozoa. JAndrol1989;10:221-31. 5. Tummon IS, Yuzpe AA, Daniel SAJ, Deutsch A. Total aerosin activity correlates with fertility potential after fertilization in vitro. Fertil Steril 1991;56:933-8.
The author elected not to respond. Paul G. McDonough, M.D., Editor, Letters
Letters-to-the-editor
657