Application of proteomic methods for identification of sperm immunogenic antigens

Abstract

Although the immunogenic properties of sperm have been explored for a few decades, none of the antigens studied so far appears to be an effective target, to inhibit the fertilization process or shown the full spectrum of sperm antigenic potential. Antisperm antibodies (ASA) collected from infertile individuals and prepubertal boys with cryptorchidism together with two-dimensional (2D) electrophoresis have been employed. Immunoreactive antigens were cored from silver stained 2D gels and analyzed by mass spectrometry (MS). The obtained sequences were searched in the published protein databases. Altogether, 35 different sperm entities were identified in accessible protein databases, out of which 10 appeared to be sperm-specific. Additionally, 6 amino acid sequences indicated novel (hypothetical) proteins. Seventeen sperm entities were detected in sera samples from immune infertile males and 18 entities in ASA-positive seminal plasma (SP). Interestingly, we identified a few sperm structures, none of them sperm specific in sera samples from infertile females. Although, infertile males from whom the ASA-positive SP samples were obtained, did not have ASA in their circulation, the range of sperm antigens detected by systematic and local antibodies overlapped to a great extent (six identical entities). Sera samples from prepubertal boys allowed to show antigens, previously thought to be only present on mature sperm. Three out of four detected were sperm-specific. Using serum and SP of ASA-positive infertile adults and sera samples of prepubertal boys with testicular failure, we have extended the range of known, immunogenic sperm proteins as well as identified some novel antigens (n=6) of human sperm for further characterization.

Immunodominant semen proteins I: New patterns of sperm proteins related to female immune infertility

“…Alpha-enolase was also found to be an isoantigen in women. This result confirms the results of Domagala et al [10], who studied cognate sperm antigens using the sera of ASA-positive infertile men and women. In our study, alpha-enolase was, however, firstly reported as a significant sperm antigen detected by the serum pool of infertile women.…”

“…To identify internal/external sperm antigens, protein extract must be prepared with a high degree of heterogeneity. Nonionic detergents [10] in general and Triton X-100 in our study have been reported as a suitable detergent [11] to solubilize proteins, and is compatible with our proteomic approach. The determination of sperm stress proteins, such as a group of HSPs, calreticulin and 78 kDa glucose-regulated protein, shows that they might be also involved in female sensitization.…”

“…Sperm is opsonized and targeted by the leukocytes [6][7][8]. Sperm also has both autoantigenic [9,10] as well as isoantigenic [11,12] potential. It induces the production of sperm-reactive T-cells, thus the formation of antisperm antibodies (ASA) may follow from exposure to the immune system.…”

“…It induces the production of sperm-reactive T-cells, thus the formation of antisperm antibodies (ASA) may follow from exposure to the immune system. In men, autoimmunity to their own sperm has already been reported particularly with respect to heat shock proteins (HSPs) [9] and alpha enolase [10]. ASA are related to some cases of unexplained infertility.…”

Identification of novel immunodominant epididymal sperm proteins using combinatorial approach

“…Several approaches have been exploited for identification of epididymal proteins such as use of lectins (Srivastav 2000), sera from infertile patients (Primakoff et al 1990, Bohring & Krause 2003, Bhande & Naz 2007, mAbs (Hegde et al 1991), subtractive screening of cDNA library (Kirchhoff 1998), computational biology (Penttinen et al 2003), micro-array (Johnston et al 2005), neonatal tolerization (Ensrud & Hamilton 1991, Khole et al 2000, and proteomics (Syntin et al 1996, Naaby-Hansen et al 1997, Shetty et al 1999, Domagała et al 2007. Proteomics has also been applied to evaluate different aspects of normal sperm function , Ficarro et al 2003, Baker et al 2005).…”