Experimental allergic aspermatogenic orchitis. 1. Isolation of a spermatozoal protein (AP1) which induces allergic aspermatogenic orchitis

Molecular cloning of an acrosomal sperm antigen gene and the production of its recombinant protein for immunocontraceptive vaccine

A monoclonal antibody, HS-63, which reacts specifically with a highly conserved sperm acrosome antigen, was shown to inhibit in vitro fertilization of mouse and human. The corresponding sperm antigen designated as MSA-63 was purified to homogeneity from mouse testes and used as an immunogen to generate polyclonal antisera in rabbits. The cDNA fragments of MSA-63 gene were cloned from mouse testis cDNA library by an immunoscreening method using polyclonal antisera specific for MSA-63. Using the established cDNA clone as a probe, the gene encoding for MSA-63 protein was found to be conserved among different mammalian species. Only one specific mRNA 1.5 kb in size was identified from the adult mouse testis among different mouse tissues. The recombinant fusion protein containing MSA-63 protein fragment was produced in Escherichia coli and used to immunize female mice. Similar to the original HS-63 monoclonal antibody, the antisera thus produced reacted only with the sperm acrosome and revealed significant inhibition to the in vitro fertilization of mouse oocytes. The results of this preliminary study suggest that it is feasible to mass produce sperm-specific antigens or their antigenic fragments by recombinant DNA technology for the development of sperm antigen-based immunocontraceptive vaccines.

Reversibility of azoospermia induced by bacillus Calmette-Guerin

A single intratesticular injection of bacillus Calmette-Guerin induces azoospermia within 3 to 6 weeks in a variety of animals without loss of androgens. After a period of azoospermia, the return of spermatogenesis was observed in dogs and monkeys. Seven dogs that showed aspermatogenesis after a local instillation of bacillus Calmette-Guerin (20-110 units per testis) again demonstrated spermatogenesis after a period of 153 to 325 days of azoospermia. Sperm counts and motility were restored to preimmunization levels within 6 weeks after initiation of spermatogenesis. In one dog, systemic treatment with antimycobacterial drugs helped to clear the bacillus Calmette-Guerin from the testis, thus hastening the reinitiation of spermatogenesis. In two monkeys injected with 110 and 160 units of bacillus Calmette-Guerin, azoospermia lasted up to 150 days. Subsequently, fertility was restored and the treated animals sired healthy offspring. A second injection of bacillus Calmette-Guerin of a lesser dose (5-20 units per testis) in these fertile dogs and monkeys again produced azoospermia. Histologically, the monkeys having a second period of azoospermia demonstrated aspermatogenic orchitis in the testis and leukocyte infiltration in the interstitium. A majority of the tubules had intact basement membranes, with a block of spermatogenesis at the spermatocyte stage. In dogs, the second azoospermia lasted for 113 to 277 days with a subsequent restoration of sperm counts and sperm motility to preimmunization levels. There were no circulating antisperm antibodies detected in sera of these animals during the azoospermic period or during its reversal. These observations suggest that the bacillus Calmette-Guerin-induced azoospermia is reversible, both in terms of sperm count and fertility.

Immunological response of guinea pigs sensitized with homologous antigens

The chemical composition of some "immunologically" pure antigens isolated from guinea pig testis and spermatozoa was correlated with their antigenic behavior. Their immunological responses were compared to select the best materials for a further isolation of chemically pure antigens. The glycoprotein extracted from the spermatozoa (T Gly) has the highest immunological potency and seems to be a T and B, depending antigen, able to induce high humoral and cell responses producing germinal cell damage, testicular lesions, and aspermatogenesis.

Analysis of mouse sperm isoantigens using specific monoclonal antibodies

Female mice were isoimmunized with homologous spermatozoa of the same strain. Hybrid cells that secrete monoclonal antibodies to mouse sperm isoantigens were generated by modified hybridoma techniques using a semi-solid Iscove's modified Dulbecco's medium containing methylcellulose for the initial cloning. Out of more than 1,000 colonies that were initially recovered for subculture, 246 were shown to produce antibodies reacting with various cytological regions of mouse spermatozoa, when methanol-fixed sperm were employed in an indirect immunofluorescent assay. More than 75% of the generated monoclonal isoantibodies were shown to bind the acrosomal regions of mouse spermatozoa. Some were found to cross-react with spermatozoa from other mammalian species including those of human, rabbit, rat, and guinea pig. However, none were shown to cross-react with mouse lymphocytes. Two-thirds of the generated monoclonal antibodies can also bind live mouse spermatozoa. By an immunohistochemical technique using testicular sections, some of these monoclonal antibodies were shown to react with specific antigens expressed during different stages of spermatogenesis. It is concluded that these mouse sperm isoantigens are sperm-specific and appear uniquely during spermatogenesis. Monoclonal isoantibodies produced in the present study may have potential applications regarding the investigations of sperm iso- or autoimmunity, spermatogenesis, and fertility control.

Conformation of bovine nerve root P2 protein: characteristics of the molecule from circular dichroism spectra

Circular dichroism (CD) was used to study the conformations of bovine nerve root P2 basic protein, its reduced and carboxymethylated derivative (RCM-P2), and its large cyanogen bromide fragment (CN1). Data in the far UV show that both the parent protein and RCM-P2 have conformations dominated by a large amount of beta structure. However, the CN1 peptide appears to exist in a largely unordered conformation. Since CN1 lacks short (20 residue) amino- and carboxy-terminal segments of the P2 protein, the spectral data suggest that these regions are important for determining and/or maintaining folding of the P2 protein in aqueous solutions. The P2 protein was found to have a distinctive CD spectrum in the near UV. The characteristics of molar ellipticities indicate that the spectrum contains significant contributions from tyrosine residues, and that these contributions suggest different environments for the two tyrosines in P2 protein. Both environments depend on protein conformation, since CD side chain absorptions are lost when P2 protein is denatured with 5 M urea.

Immunological control of male fertility

A notable feature of the male gametes is the presence in them of proteins that are "foreign" to the immune system of both male and the female. It is there that are considered responsible for the elicitation of auto- and iso-antibodies in certain natural infertility cases. By virtue of their dual application in both sexes the sperm antigens have interesting potential for exploration as possible agents for control of fertility.

Bovine peripheral nervous system myelin P2 protein: chemical and immunological characterization of the cyanogen bromide peptides

Cleavage of bovine P2 protein by cyanogen bromide (CNBr) produced peptide fractions CN1, CN2, and CN3 which were isolated by gel filtration chromatography. CN2 was found to contain two NH2-terminals (lysine and valine) and accounted for both of the cysteine residues of P2. When reduced carboxymethylated P2 (RCM-P2) was digested with CNBr, peptides CN1 and CN3 were obtained as were (1) a peptide with NH2-terminal lysine (Lys) that contained no homoserine and only one cysteine residue and (2) a peptide with NH2-terminal valine (Val) that was co-eluted with CN3. These data and the chemical characterization of all the CNBr peptides obtained from P2 and RCM-P2 suggest that isolated P2 protein has a structure composed of the CNBr peptides in the order CN3-CN1-CN2(Val)-CN2(Lys) with an intrachain disulfide bond between the cysteine residues located in the two constituent peptides of CN2, CN2(Lys) and CN2(Val). To locate the neuritogenic region(s) within the P2 protein structure, CN1, CN2, and CN3 were tested for the ability to induced experimental allergic neuritis (EAN) in Lewis rats. The disease-inducing sites of P2 protein were found only in CN1; neither CN2 nor CN3 produced disease. EAN induced by CN1 was comparable to that induced with P2 protein as determined by disease onset, clinical symptoms, and histologic lesions.

Effects of antigenic competition between sperm autoantigens and ovalbumin upon humoral and cell-mediated immunity and the development of autoimmune aspermatogenic orchitis (AIAO) in guinea pigs

The effects of antigenic competition between ovalbumin and sperm autoantigens have been studied in guinea pigs. There was an inhibition of antiovalbumin antibody production up to 60 days after immunization. The cell-mediated immunity against ovalbumin was also depressed at day 30. The simultaneous immunization with both antigens has no effect upon the humoral and cell-mediated immunity against spermatozoa. During the period of inhibition of the humoral and cell-mediated antiovalbumin response, the number of animals developing autoimmune aspermatogenic orchitis was diminished compared to those immunized with spermatozoa alone. Later on, there was no difference between the two groups. The transient inhibition of the immune response against ovalbumin can be explained by the particulate nature of the autoantigens. The sperm cells may be easily trapped by the dendritic reticular cells of the draining lymph nodes. This in turn could affect T cell recognition at early stages, orienting it predominantly toward the sperm autoantigens. At day 90 the situation returned to that present in animals immunized with ovalbumin alone.

Studies of sperm antigenicity. 6. In vivo and in vitro cellular reactivity in guinea pigs sensitized with fractions of guinea pig spermatozoa

Normal guinea pig spermatozoa cells were homogenized by a French pressure cell. Three soluble and three insoluble fractions were obtained by ultrascentrifugation and (emulsified in CFA) were used for guinea pig sensitization. The following were observed: 1) all fractions were immunogenic except one; 2) in vivo and in vitro delayed hypersensitivity was elicited in animals immunized with these fractions; 3) two distinctive histopathologic lesions were observed in the testes of sensitized animals: lesions of orchitis type developed in animals injected with some fractions. Other fractions induced lesions of aspermatogenic type. These results correlated well with delayed hypersensitivity results obtained by in vivo and in vitro tests. Although some other spermatozoal fractions did not cause severe changes in the testes. The lack of sperm accumulation in the epididymis was obvious.

Experimental allergic aspermatogenic orchitis. IV. Chemical properties of sperm glycoproteins isolated from guinea pig testes

Of four glycoproteins isolated from guinea pig testes, two were aspermatogenic (types I and IV) and two (types II and III) were inactive. The glycoproteins were rich in carbohydrate, varying from 41.5% to 49.5% carbohydrate by weight. Each glycoprotein had a unique amino acid composition, but in general low levels of tyrosine, tryptophan, and basic amino acids were found along with relatively high contents of serine, threonine, glutamic acid, and proline. Types I and IV glycoproteins were remarkably stable; their aspermatogenic activity was not affected by urea, trypsin, or heating at 100 degrees C in water or in 1 M HCl for 15 min. Carbohydrate analysis revealed little difference in the monosaccharide compositions of types I and IV glycoproteins, except that only the type I contained sialic acid. In contrast, types II and III glycoproteins lacked sialicacid and fucose and contained much less mannose. Both N-acetylglucosamine and N-acetylgalactosamine were present in all four glycoproteins, and they dominated in the types II and III. Fucose and at least 20-25% of the galactose appeared to occupy terminal positions in type IV glycoprotein as shown by their release after 15 min hydrolysis in 1 M HCl. All of the glycoproteins contained a relatively high percentage of galactose by weight, from 12.6 to 19.3%. The molecular weights of the glycoproteins were estimated by sodium dodecyl sulfate gel electrophoresis to be 47000, 105000 and 18000 respectively for the types I, II, and IV; type III glycoprotein showed two major bands, with molecular weights of 41500 and 22800. All the above molecular weight values are probably overestimated because of high carbohydrate content. The molecular weight of type IV glycoprotein was found to be 13000 by ultracentrifugation; a corrected value of 29000 was calculated for type I glycoprotein.

Experimental allergic aspermatogenic orchitis. II. Some chemical properties of the AP1 protein of the sperm acrosome

The AP1 protein, a unique aspermatogenic protein localized in the sperm acrosome, exists as a single polypeptide chain of 136 amino acids, as shown by a single band on gel electrophoresis in sodium dodecyl sulfate and the recovery of the expected 21 to 22 tryptic peptides on peptide mapping. The AP1 protein appears to exist in a compact, highly stable conformation, as shown by its resistance to trypsin hydrolysis. Its aspermatogenic acitivity is not affected by trypsin treatment, by heating at 99 degrees C for 1 h, by 8 M urea, or by acid conditions. After reduction and alkylation, however, the molecule appears to open up, since it becomes hydrolyzable by trypsin and migrates more slowly on gel electrophoresis at pH 2.7 and 8.6. After alkylation, the AP1 protein still migrates as a single band at pH 2.7. The AP1 protein shows microheterogeneity near its isolectric point at pH 8.6; each of five bands shows the same amino acid analysis. Aggregation was not observed following treatment with dimethylsuberimidate. The molecular weight of 15 000, obtained from gel electrophoresis consists of 136 amino acids with a relatively high content of proline, half cystine, glycine, histidine and tryptophan. No galactose, mannose, fucose, glucose, or hexosamines were found; the AP1 protein is thus not a glycoprotein.