Variability in serologically detected male antigen titer and some resulting problems: a critical review

The production of anti-H-Y monoclonal antibodies: their potential use in a sex test for bovine embryos

In an attempt to improve the accuracy of sexing bovine embryos, new anti-H-Y monoclonal antibodies were produced and selected, using an extended screening procedure. In addition to the commonly used screening of soluble H-Y antigen sources, such as testis supernatant and Daudi supernatant, the binding specificity to cell surface H-Y antigen was tested also. A radioimmunoassay (RIA) employing male and, as a control, female bovine lymphocytes, and enzyme-linked immunosorbent assays (ELISAs) on solubilized membrane fractions resulted in the selection of a number of clones producing monoclonal antibody (mAb) with male-enhanced binding. Four of the anti-H-Y mAb were assessed for binding to Day 7 or 8 bovine embryos. The accuracy of sexing bovine embryos ranged from 58% to 71%. Two of the four antibodies did not react with presumed soluble H-Y antigen-containing sources in an ELISA. These results raise doubts about the suitability of the presumed soluble H-Y antigen sources, Daudi, TM4 and testis supernatant, to be used in screening tests for anti-H-Y antibodies.

Production and characterization of monoclonal antibodies against the H-Y antigen

Monoclonal antibodies against the H-Y antigen were produced using spleen cells from female C57BL/6 mice hyperimmunized with cells from syngeneic males. Anti-H-Y positive clones were detected by enzyme immunoassays. Supernatant fluids from Daudi cell cultures and testicular cell preparations taken from mice, rabbits or calves served as presumptive sources of H-Y antigen. In addition, testis supernatant from genetically sterile mice was used. Male specificity was ascertained by the fact that the antibodies could be absorbed with spleen cells from male but not from female mice. Binding of the antibodies to H-Y antigen on the surface of male and female cells, obtained from a number of tissues and species, was confirmed by an indirect immunofluorescence assay. Several monoclonal antibodies appeared to be positive in all assays tested, suggesting that the molecule conferring the H-Y antigenicity lacks species-specificity and appears to be identical for soluble and membrane-bound H-Y antigen.

Reduced level of sex-specific antigen (H-Y antigen) on lymphocytes in some patients with bilateral cryptorchidism

Sex-specific (Sxs) antigen on the surface of nucleated cells from normal human males seems to be essential for the formation of testes. The relative quantity of the antigen on lymphocytes was evaluated by absorption experiments in a complement-dependent cytotoxicity test or in an ELISA technique using antisera against Sxs antigen produced by immunization of female rats. Lymphocytes from 13 normal males were Sxs-antigen positive, and cells from 12 normal females were characterized as Sxs-antigen negative. However, in the testing of lymphocytes from nine boys with bilateral cryptorchidism, only six revealed a normal male absorption pattern, whereas the antigen level on cells from three boys, all of them with normal karyotype, was reduced compared with the normal male level. No correlation between Sxs-antigen level and testosterone response after treatment with hCG could be demonstrated.

H-Y antigen and sex determination

The primary development of a male rather than a female gonad in mammals is determined by the presence of a Y chromosome. The other property unique to the Y chromosome is the occurrence of a cell-surface antigen (designated H-Y) which distinguishes male from female. Thus it was determined that male grafts were rejected by otherwise histocompatible females of the same inbred strain and later that H-Y-specific cytolytic T cells were produced by these grafted mice. When it was determined that females grafted with male skin produced antibody defining a serologically detectable male antigen (which may or may not be the same as H-Y), further immunogenetic analysis of this antigenic system became possible in terms of humoral and cellular factors. By using this assay it was demonstrated that the antigen was phylogenetically conserved and that it was expressed in the male mouse embryo as early as the 8-cell stage of development. The notion that H-Y was a single molecular species responsible for triggering the indifferent gonad to differentiate into the testis became a widely accepted hypothesis. In this report the H-Y antigenic system is traced historically from its original description to the role played in testis development. Data are presented which suggest that although H-Y is a male-specific factor and may play a role in male sex determination, it is unlikely that it is the primary inducer of testis differentiation.

H-Y intermediate phenotype in male pseudohermaphroditism

A child with ambiguous genitalia was born after an uncomplicated pregnancy. Laparotomy revealed intraabdominal hypoplastic testes containing normal appearing Leydig cells; germ cells were present in the left gonad, not in the right. The karyotype was 46,XY in blood leukocytes and in fibroblasts cultured from the gonads; there was no evidence of mosaicism. Endocrinologic study revealed no disorder of steroidogenesis. Androgen receptors were not studied. Serologic evaluation of blood leukocytes revealed the presence of H-Y antigen, but there are reasons to believe that less H-Y antigen was present in the cells of the patient than was present in corresponding cells from normal males. Gonadectomy and clitoral recession were performed at 3 weeks of age, and the patient was reared as a girl. We speculate that reduced expression of H-Y may have induced aberrant development of the gonads.

Diagnostic applications of H-Y serology: H-Y negative phenotype in cells from 45,X/46,XY fetus with testes

Sexual dysmorphism should be considered likely in cases in which H-Y- phenotype and XY complement are found together. In the case described here, a pregnancy was terminated at nineteen weeks of gestation after 45,X and 46,XY cell lines were detected among cultured amniocytes. The fetus was a male with hypospadias and intraabdominal testes containing irregular tubules and hyperplastic interstitium. Cultured skin fibroblasts, containing 45,X and 46,XY lines in ratio of 18:2, were typed H-Y antigen negative. This underscores the danger of predicting gonadal type on the basis of somatic H-Y phenotype.

Gonadal tumor and H-Y antigen in 46,XY pure gonadal dysgenesis

Six cases of Swyer's syndrome (46,XY pure gonadal dysgenesis) are reported. Three patients, without gonadal tumor, had female H-Y antigen. Three patients, after gonadal tumor ablation, had intermediate H-Y antigen levels. Repeated blood samples were obtained from two siblings. H-Y antigen level in the first sibling, who presented with a gonadoblastoma and underwent a gonadectomy before the H-Y assays, was intermediate, and did not show any significant variation for 21 months. H-Y antigen level in the second sibling showed an increase in the male range, presumably due to the presence of gonadoblastomas. After resection of the tumors, H-Y antigen level became intermediate. These findings suggest a relation between the tumorization potentiality of the gonadal remnants and the H-Y antigen levels in 46,XY pure gonadal dysgenesis.