Antisperm antibodies detection by flow cytometry is affected by aggregation of antigen-antibody complexes on the surface of spermatozoa

Detection of Chlamydia trachomatis inside spermatozoa using flow cytometry: Effects of antibiotic treatment (before and after) on sperm count parameters

There is increasing evidence that Chlamydia trachomatis (CT) infection can directly affect male fertility. However, only few have investigated the effects of CT on semen parameters, and mostly with inconclusive results. The main aims of this study were to identify CT inside spermatozoa, and the possible pre and post antibiotic treatment effects on the overall semen parameters. We developed a flow cytometric method for the detection of CT inside spermatozoa (SPI™). Briefly, sperm cells were fixed, membrane permeabilized and DNA was loosened using DNAse. Sperm cells were incubated with a primary monoclonal antibody against CT and with a secondary fluorescent antibody (vs primary), and analysed using a flow cytometer. Of 2415 infertile individuals, 48.61% were found positive for CT. 170 CT+ samples were included in the CT antibiotic treatment study. 78.82% (134/170) of the CT+ showed a significant reduction in the percentage of the iCT infected spermatozoa after the antibiotic treatment; 59.70% (80/134) decreased to non-detectable levels. Spermcount data were also recorded. Spermatozoa morphology (normal and teratozoospermia index, TZI) and motility (fast progressive and non-progressive spermatozoa) were statistically significant altered in CT+ pre-treatment vs control group. CT antibiotic treatment showed statistically significant effects on normal spermatozoa morphology, mid-piece and tail defects, and TZI. The study demonstrated that semen flow cytometric analysis of semen could be a valuable tool for faster and accurate identification of individuals with asymptomatic CT infection. It also identified a positive effect of antibiotic therapy on semen parameters, that could help males with infertility.

Mouse t-complex protein 11 is important for progressive motility in sperm†

The t-complex is defined as naturally occurring variants of the proximal third of mouse chromosome 17 and has been studied by mouse geneticists for decades. This region contains many genes involved in processes from embryogenesis to sperm function. One such gene, t-complex protein 11 (Tcp11), was identified as a testis-specific gene whose protein is present in elongating spermatids. Later work on Tcp11 localized TCP11 to the sperm surface and acrosome cap and implicated TCP11 as important for sperm capacitation through the cyclic AMP/Protein Kinase A pathway. Here, we show that TCP11 is cytoplasmically localized to elongating spermatids and absent from sperm. In the absence of Tcp11, male mice have severely reduced fertility due to a significant decrease in progressively motile sperm; however, Tcp11-null sperm continues to undergo tyrosine phosphorylation, a hallmark of capacitation. Interestingly, null sperm displays reduced PKA activity, consistent with previous reports. Our work demonstrates that TCP11 functions in elongated spermatids to confer proper motility in mature sperm.

Standardization of a method to detect bovine sperm-bound antisperm antibodies by flow cytometry

The objectives were to standardize some methodological and analytical aspects of a direct technique to detect sperm-bound antisperm antibodies (ASAs) in bovine semen using flow cytometry, including the effects of prefixation of sperm membranes with formalin buffer solution and inclusion of dead cells in the analysis. Fourteen Angus bulls, including ASA-positive (experimentally induced ASAs) and 10 reproductively normal ASA-negative bulls, were used. Fixation of sperm membranes had no significant effect on the percentage of IgG- or IgA-bound spermatozoa detected by flow cytometry. However, including dead cells in the analysis increased the percentage of IgG-bound spermatozoa in fixed (live and dead 18.6 ± 9.7% and live 1.3 ± 0.5%; median ± SEM) and nonfixed samples (live and dead 18.8 ± 9.2%, live 1.5 ± 0.6%; P = 0.0029), as well as IgA-bound spermatozoa in fixed (live and dead 16.3 ± 6.4%, live 0.3 ± 0.5%) and nonfixed samples (live and dead 21.4 ± 4.6%, live 1.0 ± 0.5%; P = 0.0041) in semen from ASA-negative bulls. Intrasample, intra-assay, and interassay coefficients of variation (CV) were 0.8%, 4.6%, and 5.3%, respectively, for determination of sperm-bound IgG, and were 2.8%, 8.4%, and 40.3% for determination of sperm-bound IgA. Despite the high interassay CV for IgA determination, all ASA-positive bulls consistently had high percentages of IgA-bound spermatozoa. Flow cytometry correctly identified ASA-positive bulls. Confocal laser microscopy confirmed binding of ASAs to sperm heads and cytoplasmic droplets, and less frequently to midpieces and principal piece. In conclusion, although fixation was not necessary, dead cells should be excluded from the analysis, because ejaculates with a large proportion of dead cells can yield false-positive results. Flow cytometry was accurate and reliable for detection of sperm-bound IgG and IgA and discrimination between ASA-positive and ASA-negative bulls.

Antisperm immunity and infertility

Immunoinfertility is one of several causes of infertility in humans. Although progress on antisperm immunity and infertility has advanced during the past three decades, the nature of a real antisperm antibody (ASA) is still poorly understood. Dozens of sperm antigens have been isolated and characterized in association with infertility. However, it is difficult to identify a single predominant target antigen that could interact with all the ASAs. There are some protective mechanisms preventing ASA production in males and females. As chronic infection, vasectomy and vasovasostomy, heavy metals, and testicular cancer and torsion may induce the production of ASAs, they may be responsible for decreased motility and sperm penetration of cervical mucus, and the blockage of the acrosome reaction and the sperm-egg interaction. Many ASA assay methods have been developed, each with advantages and disadvantages. Efforts for the treatment of ASA-mediated infertility have been attempted. However, current therapy for ASA-associated infertility is almost empiric and largely unproven.

Testicular Isoform of Angiotensin I-Converting Enzyme (ACE, CD143) on the Surface of Human Spermatozoa: Revelation and Quantification Using Monoclonal Antibodies

PROBLEM

The elucidation of the role of angiotensin-converting enzyme (ACE, CD143) in the male fertility has been hampered by the absence of highly specific antibodies to the native testicular isoform (tACE). The quantification of tACE expression on human-ejaculated spermatozoa was performed using a novel panel of monoclonal antibodies (mAbs).

METHOD OF STUDY

The expression of tACE on the surface of live and fixed human spermatozoa was analyzed by flow cytometry and immunocytochemistry using new mAbs to human tACE.

RESULTS

Monoclonal antibodies 1E10 and 4E3 similarly revealed tACE on the surface of live and fixed spermatozoa. The high percentage of tACE-positive spermatozoa (median 81%) was revealed in the swim-up fraction of sperm. Antibody-induced tACE shedding occurs preferentially from live sperm with defective function and/or morphology. 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 the defective cells.

CONCLUSIONS

The new mAbs recognizing the C-terminal domain of human ACE are useful tools for quantification of tACE expression on human live and fixed spermatozoa and further adequate analysis of the tACE role in reproduction.

A Quantitative Method for Determining Polarization of Neutrophil Adhesion Molecules Associated with Ischemia Reperfusion

Ischemia-reperfusion-induced neutrophil adhesion to endothelium is CD18-dependent, but information regarding polarity of CD18 adhesion molecules remains speculative. This study evaluated neutrophil adhesion using an in vitro cell adhesion assay and introduces a quantitative method of measuring CD18 membrane distribution using confocal microscopy. Neutrophils from normal animals were isolated from whole blood and incubated with plasma from rat gracilis muscle flaps with no ischemia and reperfusion (nonischemic control, n = 10) or 4 hours of ischemia and 90 minutes of reperfusion (ischemia/reperfusion, n = 10), on coverslips pretreated with and without (phosphate-buffered saline) soluble intercellular adhesion molecules. Coverslips without intercellular adhesion molecules represented a negative control (intercellular adhesion molecules were required for adhesion). Percent adherence to intercellular adhesion molecules was expressed as a ratio of adherent cells/total cells. CD18 polarization was assessed by staining neutrophils with fluorescein isothiocyanate-labeled anti-CD11b, followed by confocal microscopy and Z-stack analysis. Membrane-associated CD18 was expressed as fluorescence intensity units in three equal areas of the cell membrane. Capping was defined as twice as much fluorescence in 33 percent of the cell membrane as in the remaining 67 percent. Neutrophils exposed to ischemia and reperfusion plasma showed a significant increase in adhesion (0.8 +/- 0.1 percent versus 16.7 +/- 2.2 percent, p < 0.001) and CD18 polarization (6.2 +/- 1.7 percent versus 43.9 +/- 12.2 percent, p = 0.0206) compared with controls. This article describes an in vitro assay that reliably reproduces the neutrophil adhesion phenomenon associated with ischemia-reperfusion injury. Results from confocal microscopy allowed for quantitative estimation of membrane-associated receptor polarization.