Monoclonal antibody inducing human sperm agglutination

Ion-channels reconstituted into lipid bilayer from human sperm plasma membrane

Ion environment and ionic fluxes through membrane are thought to be important in the spermatozoa's maturation, capacitation, and the initiating process of gamete interaction. In this work, the membrane proteins isolated from human sperm plasma membrane were reconstituted into planar lipid bilayers via fusion, and the ion channels activities were observed under voltage clamp mode. In cis 200//trans 100 mM KCl solution, a TEA-sensitive cation-selective channel with a unit conductance of 40 pS was recorded. In a gradient of 200//100 mM NaCl solutions, a Na(+)-selective channel with a unit conductance of 26 pS was recorded. In both cases, reversal potential was about-18 mV, which is close to the predicated value of a perfect Nernst K+ or Na+ electrode. In 50//10 mM CaCl2 solution, a cation channel activity with a unit conductance of 40 pS and reversal potential of about -20 mV was usually observed. In 200//100 mM NMDG(N-methyl-D-glucamine)-Cl solution, where the cation ions were substituted with NMDG, a 30-pS anion-selective channel activity was also detected. The variety in the types of ion channels observed in human spermatozoa plasma membrane suggests that ion channels may play a range of different roles in sperm physiology and gamete interaction.

Cation and anion channels in rat and human spermatozoa

Ionic fluxes are thought to be important in the initiating process of gamete interaction such as acrosome reaction. Different populations of ion channels in rat and human spermatozoa were investigated using the planar lipid bilayer technique. Membrane proteins were isolated from rat and human sperm and inserted into lipid bilayer via fusion. We observed K(+) selective and Na(+)-selective channels, as well as divalent permeable cation channels in membrane preparations from rat sperm K+ channels, which were sensitive to the K+ channel blocker, tetraethylammonium (0.1 mM), exhibited a mean single channel conductance of 24 pS. Whereas, larger conductance, 109 pS, was found to be associated with Na+ channels. Low conductance anion channel, 15 pS, was also observed when permeant cations in the bathing solutions were substituted with N-methyl-D-glucamine leaving Cl- as the major permeant ion species. This channel exhibited a slower channel open and closed kinetics when compared to other cation channels. Both cation and anion channels with characteristics similar to that found in rat sperm were also observed in preparations from human sperm. The variety in the types of ion channels observed in rat and human spermatozoa suggests that ion channels may play different roles in sperm physiology and gamete interaction.

Fertility studies with antisperm antibodies

Serum obtained from an infertile subject possessed antibodies that interacted with a human sperm glycoprotein with an estimated M(r) of 17,550 and pI of 5.65 containing 17.7% neutral hexoses and designated as the BS-17 component. Polyclonal antibodies raised against the BS-17 antigen blocked the capacity of human sperm to fertilize zona-free hamster ova in vitro; however, the antibodies did not influence the binding of human sperm to zone-free ova or alter the motility of human sperm. The antibodies inhibited the capacity of mouse sperm to fertilize ova upon in vivo insemination. The BS-17 antigen was detected in human, rat, mouse, rabbit, and hamster sperm by an immunocytochemical method, using polyclonal anti-BS-17 antibodies. Intense staining occurred over the surface of the acrosomal region of all mammalian sperm. The results suggest that the production of anti-BS-17 antibodies contribute to infertility by preventing the capacitation of sperm and/or by blocking the ability of capacitated sperm to fertilize the egg.

Infertility induced in rats by immunization with synthetic peptide segments of a sperm protein

Three peptide segments (YAL-198, YAL-201 and YAL-212) corresponding to the extracellular domain of a human sperm protein designated as YWK-II antigen were synthesized as multiple antigen peptide (MAP). Male and female rats were immunized with the YWK-II-MAPs and fertility determined. In a group of 12 female rats immunized with YAL-198, seven animals were infertile and two animals were subfertile. When immunized with YAL-201 and YAL-212, 4 and 2 animals were infertile, respectively. In a group of 15 males immunized with YAL-198, 2 animals were infertile and 6 were subfertile. Two animals immunized with YAL-201 were subfertile. All control male and female rats immunized with bovine serum albumin and adjuvant were fertile. Sera obtained from infertile rats immunized with YAL-198 contained higher titers of antibodies compared to those obtained from fertile animals. The present study shows that immunization with synthetic peptide segments of a sperm protein can effectively reduce fertility.

Gene expression of human sperm component related to A4 amyloid precursor protein

Monoclonal antibodies were raised against a specific human sperm protein and designated as the YWK-II mAb. The partial cDNA encoding the protein was isolated from a rat testis lambda gt11 expression library and the amino acid sequence of the protein was deduced. The cytoplasmic-transmembrane domains of the deduced protein had high homology with the A4 amyloid precursor protein of Alzheimer's disease. To evaluate the stage of spermatogenesis when the gene was expressed, single-stranded 35S-labeled RNA probes were prepared from the cDNA. By an in situ hybridization technique the mRNA for the antigen was detected in germ cells at all stages of spermatogenesis. The finding that the gene is expressed in spermatogonia suggests possible involvement in the initiation of germ cell differentiation or in the detachment of spermatogonia from the basement membrane.

Identification of the sperm antigen interacting with antibodies in serum from an infertile woman

Serum (IS) obtained from an infertile woman induced head-to-head agglutination of human sperm. The immunoglobulin G (IgG) fraction of the IS was prepared by ammonium sulfate fractionation and DEAE cellulose chromatography. The IgG localized to the post-acrosomal region of the sperm, determined by indirect immunofluorescence and interacted with a human sperm protein with an estimated Mr of 80 kDa, determined by immunoblotting. The identity of the interacting sperm antigen was verified by isolating the 80 kDa sperm protein by affinity chromatography. The present results suggest that the anti-80 kDa antibodies may be responsible for the infertility.

Characterization of cDNA encoding a human sperm membrane protein related to A4 amyloid protein

A rat testis lambda gt11 cDNA library was screened with a monoclonal antibody raised against a human sperm membrane protein designated YWK-II. A clone was found with a cDNA insert composed of 1837 base pairs that contained an open reading frame coding for 191 amino acid residues. The deduced polypeptide contained a segment with high homology to the transmembrane-cytoplasmic domains of the A4 amyloid protein found in brain plaques of Alzheimer disease patients. A sequence of basic amino acid residues, Arg-Lys-Arg, was found instead of Lys-Lys-Lys at the probable membrane-cytoplasmic junction that may be a unique property of sperm membrane proteins.

Immunocytochemistry of male reproductive organs

Immunological techniques have enabled us to see that mammalian sperm undergo complex surface changes during maturation in the male reproductive tract. Binding affinity and sperm surface binding domains have been demonstrated using immunocytochemical technique. Recent studies using monoclonal antibodies suggest that these highly specific probes are useful for detecting changes in the sperm surface during epididymal transit and in defining the role of these complex changes in sperm maturation and the process of fertilization. Studies involving immunological mapping of the sperm surface, in parallel with immunohistological and functional inhibition test, have provided important information concerning the role of individual sperm antigens in fertility. A better understanding of local antibody production and cell-mediated immune responses in the male reproductive tract has also led to the understanding of immunological infertility. Sperm membrane is comprised of multiple domains each of which is sharply demarcated, with a unique composition and physiological role.

Monoclonal antibodies to human trophoblast and sperm antigens: report of two WHO-sponsored workshops, June 30, 1986--Toronto, Canada

Two WHO-sponsored workshops were recently held to obtain a consensus view from researchers active in the field of reproductive immunology on the current status of the application of monoclonal antibodies to studies of molecular events underlying reproduction and to determine the feasibility of using this approach to identify trophoblast- or sperm-specific antigens that might represent suitable candidates for the development of antifertility vaccines. A total of 66 mouse monoclonal antibodies reacting with human sperm and 45 monoclonal antibodies reacting with human trophoblast membrane components were submitted by 29 laboratories. These were evaluated in coded form by 42 laboratories with the appropriate expertise in biochemistry, immunohistology and tests of reproductive cell function. The majority of both anti-sperm and anti-trophoblast monoclonal antibodies cross-reacted with cellular elements in non-reproductive tissues. However, at least five monoclonal antibodies (two anti-trophoblast and three anti-sperm) appeared to demonstrate sufficient specificity to warrant further investigation as reagents for the identification of antifertility vaccine candidates.

Isolation and characterization of a rabbit sperm tail protein

Rabbit sperm tails were obtained by a nitrogen cavitation procedure and separated by discontinuous sucrose gradient centrifugation. Proteins were extracted from sperm tails with 3[(3-cholamidopropyl)-dimethylammonio]-1-propane sulfonate (CHAPS) and separative disk electrophoresis and DEAE-trisacryl column chromatography. A protein with an estimated mol wt of 20.1 +/- 1.1 kD was isolated and found to be homogeneous by SDS-PAGE and designated as rSMP-B. The isoelectric point of rSMP-B was in the range of pH 4.4-4.7. The amino acid composition was determined, and glycine was identified as the N-terminal residue. Antisera were raised against purified rSMP-B. Using a peroxidase-antiperoxidase method, the rSMP-B antigen was located on the surface of the midpiece and tail of the sperm. Testis sections showed intense staining of late spermatids located within the seminiferous tubules. Adult male rabbits were inoculated with rSMP-B protein and Freund's adjuvant. The testis and epididymis of the immunized animals showed absence of sperm. The immunolocalization findings and the immunization data suggest that rSMP-B is formed in late spermatid and that it is an essential structural component of sperm.

Immunodissection of sperm surface modifications during epididymal maturation

Mammalian spermatozoa undergo changes in morphology, composition, and function during transit through the epididymis. These changes correlate with acquisition by sperm of the ability to fertilize ova. It has been found that sperm from the cauda epididymidis, but not those from the caput epididymidis, are able to bind to the zona pellucida. This would imply a modification in sperm surface characteristics. Biochemical and immunological studies have demonstrated changes in sperm surface composition during epididymal maturation. These changes involve addition of epididymal secretory products to the sperm surface, loss or alteration of existing sperm surface molecules, and possibly the unmasking of preexisting molecules or epitopes. Several laboratories have studied the epididymal secretory proteins in the rat, but a consensus has not been reached on the identification, characterization, source, and sperm surface association of these proteins. Monoclonal antibodies are beginning to be used to characterize sperm surface components and sperm maturation antigens. They are proving to be valuable tools for the dissection of epididymal maturation when used in conjunction with biochemical and physiological approaches.

Immunolocalization of a sperm membrane protein in human male reproductive organs

A monoclonal antibody that induces agglutination of human sperm was used to localize the interacting antigen in various tissues by indirect immunofluorescence. The antibody localized to the immature sperm and Sertoli cells of the seminiferous tubules, simple cuboidal epithelial cells of the rete testis, and the columnar epithelial cells of the ductuli efferentes. The present results show that the interacting protein is found associated with germ cells undergoing spermatogenesis.