A monoclonal antibody, EC-1, derived from a syngeneically multiparous mouse alters in vitro fertilization and development

Monoclonal antibodies to epididymis-specific proteins using mice rendered immune tolerant to testicular proteins

Monoclonal antibodies (mabs) have been used as a powerful tool for identification of newer sperm proteins. However, conventional hybridoma technology rarely provides chance to obtain mabs to epididymal proteins. To increase this chance, we have used an alternate method of neonatal tolerization. In this protocol, animals were tolerized at birth using testicular proteins followed by immunization with cauda epididymal sperm protein (which is a cocktail of proteins both from testicular and epididymal origin). This protocol induced a specific immune response to epididymal sperm proteins. Spleen from one of these animals was then used for preparation of mabs. This fusion resulted in a number of mabs reacting specifically to epididymal proteins. Although mabs identified a protein of approximately similar molecular weight on 1-dimensional Western blot analysis, there were differences in regional localization on rat sperm as seen by indirect immunofluorescence. Immunohistochemical localization of these proteins in rat epididymis showed region specific synthesis. The synthesis of proteins was seen in the distal caput epididymis, and maximum expression was seen in supranuclear region of corpus epithelium. The proteins were localized on sperm from corpus and cauda region. Epididymis specific synthesis of the proteins and agglutinating nature of the mabs to these underlines the functional importance of these proteins in sperm maturation in epididymis. These antibodies could therefore, be used as tools for understanding the physiology of maturation of sperm in epididymis and role of the epididymal protein in fertilization.

Macrophages and migratory cells in endometrium relevant to implantation

The implantation of an appropriately developed embryo into a suitably conditioned uterine lining depends on the synchronous maturation of the preimplantation embryo and uterine lining. The pre- and postimplantation embryo also requires protection from immunocompetent maternal immune effectors. Preimplantation embryo development is affected by genotype, intercellular communication and autocrine growth factors (polyamines, TGF-alpha, TGF-beta 1, PAF). Factors of maternal origin may also enhance embryo development (EGF, TGF-alpha, TGF-beta 1, IGF, polyamines). The preimplantation embryo signals its presence to the mother by release of factor(s) such as IFN-alpha-II and a PAF-like factor. PAF may induce EPF in the mother and enhances vascular permeability at the implantation site. Uterine or peritoneal leukocytosis may inhibit development via toxic effects of lymphokines/monokines (IL-2, IL-1?, IFN-gamma, TNF-alpha). Immunoprotection of the preimplantation embryo is conferred by embryo derived maternal factors (EPF, T-cell suppressor factors). The uterus is receptive during a limited period of time (implantation window) and the substrate adhesion molecules produced by uterine and embryonic trophectoderm cells are crucial for the initial stages of implantation. At implantation, trophoblast expression of MHC and non-MHC antigens is shut off and both immunocompetent maternal cells (macrophages, dendritic cells, granulocytes, IELs, immunocytes) and lymphatics become sparse at implantation sites. Peri-implantation cytokines of maternal origin, such as CSF-1, GM-CSF and IGF-1 binding protein, are probably important for trophoblast growth and development. Immuno-protection of the embryo at this stage may be mediated by embryo derived factors that inactivate macrophages and by a population of large, hormone dependent Lyt 2+ (CD8+) suppressor cells. It is possible that these CD8+ cells respond to progesterone and secrete molecules that inactivate natural effector (NK-type) cells against trophoblast. Prostaglandins (PGE2) may play a brief role in immunosuppression at the time of implantation but its role is probably more important with respect to the decidual response. Defects in the pre- and peri-implantation stages of pregnancy may lead to delayed failure in the form of clinical miscarriage.

A monoclonal antibody, MA21, recognizes a surface component that is present on F9 teratocarcinoma cells and that appears vectorially on the trophectoderm of peri-implantation-stage mouse blastocysts

A monoclonal antibody (MAb) "MA21", derived from lymphoid tissue of a multiparous mouse and selected for binding to mouse teratocarcinoma cell line F9, recognizes a surface antigen that appears on peri-implantation-stage mouse blastocysts. In indirect immunofluorescence assays, MAb MA21 does not bind to 1-cell-through morula-stage embryos, nor to early, 3.5-day post-coitum (p.c.) blastocysts. When 3.5-day p.c. blastocysts are maintained 17 h in vitro and then assayed, MAb MA21 binds to a limited number of trophectoderm cells that are centered at the embryonic pole. As culture time lengthens, the number of antigen-expressing trophectoderm cells increases, forming a cap that spreads from the embryonic pole into the abembryonic region. Embryos maintained 48 h in vitro bind MAb MA21 over as much as 100% of the trophectoderm surface. MAb MA21 does not bind to the inner cell mass. When mouse pregnancy uteri are assayed by the immunoperoxidase method, MAb MA21 binds to extra-embryonic ectoderm and trophectoderm of 5-day p.c. implanted blastocysts, but does not bind to 6-day p.c. blastocysts. MAb MA21 recognizes a component with an estimated mol. wt of 44,000 from NP-40 detergent extracts of F9 cells and peri-implantation-stage mouse blastocysts. The component appears to be firmly associated with the plasma membrane; it is resistant to removal by high salt or moderate concentrations of non-ionic detergent.

Human sperm carbohydrate antigens defined by an antisperm human monoclonal antibody derived from an infertile woman bearing antisperm antibodies in her serum

The epitope structure of the human sperm antigen reacting with antibodies present in sera of infertile women has been studied using mAb H6-3C4, which produces immobilization of human sperm in the presence of complement. Another antibody, NUH2, which also induces human sperm immobilization, was used to substantiate the presence of a receptor on sperm involved in susceptibility to immobilization. Both antibodies defined type 2 chain polylactosamine structure. H6-3C4 is directed to internally located repetitive N-acetyllactosamine, i.e., sialyl-i, i, or fucosyl-i. NUH2 defines binary alpha 2----3 sialyl type 2 chain, i.e., sialyl-I. Thus, the presence of antibodies in the sera of infertile women directed to sperm lactosaminoglycan or lactosaminolipid could be the basis for infertility in these cases.

Mouse embryonic cells become susceptible to CTL lysis after midgestation

The susceptibility of murine embryonic cells to CTL lysis has been assessed. Zona-free blastocysts were not lysed during 6 hr incubation with CTL sensitized against the embryonic genotype and remained capable of implantation and normal development in vivo as well as outgrowth in vitro. Freshly dissociated cells from postimplantation embryos before the 13th day of gestation were not lysed in a 51Cr-release assay, but cells from 13- to 16-day embryos were susceptible to lysis. Cells from Day 12 embryos cultured for 40 hr in the presence or absence of interferon became susceptible to CTL lysis. Cultured cells from Day 10 embryos were only lysed following culture in medium containing interferon. Cell populations lysed in the CTL assay remained resistant to lysis by NK effector cells. These experiments indicate that the murine fetus is protected from the maternal immune system at least during the first half of pregnancy by an intrinsic ability of early embryonic cells to resist cell mediated lysis. Suppression of maternal CTL responses may not be essential for fetal survival until later stages of gestation.