Genetic control of H-Y synthesis. A hypothesis

Two new ELISAs using monoclonal H-Y antibody

Biotin-conjugated monoclonal H-Y antibody was used to detect soluble H-Y antigen, directly, in two novel enzyme-based systems: a sandwich or 'capture' ELISA and an inhibition ELISA. In each case, soluble H-Y was readily detected in samples known to contain the antigen, provided that positive and negative samples were compared on an equivalent protein basis. By adding increasing concentrations of inhibitor (antigen) we define the useful range of the assays to be between 0.6 and 20.0 micrograms of added protein. Both sandwich and inhibition ELISAs gave similar results with antigens tested. The methods can accordingly be applied as direct diagnostics in the study of sex determination and in the assignment of gender.

Enzyme immunoassay of H-Y antigen: experimental and clinical applications

A newly developed enzyme-linked immunosorbent assay (ELISA) was applied for studying H-Y antigen in buffaloes, cattle, horses and humans. A monoclonal H-Y antibody was absorbed with cells from males or females and was then tested against fluid samples known to contain soluble H-Y antigen. In this system, positive absorption manifested itself by a fall in optical density relative to the optical density scored using unabsorbed antibody; this finding signified the presence of H-Y in the absorbing cells. In each of the four species, the fall in optical density was pronounced after absorption with male cells, but some decrease was also evident after absorption with female cells, indicating a degree of nonspecific attachment of the antibody.

H-Y typing by ELISA in a 46,X,dic(Y)(q11.2101) male: effects of a nonmosaic Yp duplication

A new ELISA was used to measure H-Y antigen in cultured fibroblasts from a male with 46,X,dic(Y)(q11.2101) involving duplication of Yp. Aliquots of monoclonal H-Y antibody were absorbed with 1, 2, 4, or 8 X 10(6) cells from the 46,X,dic(Y) male, or with corresponding numbers of cells from a normal XY male and a normal XX female, and then were tested for residual activity against a soluble antigen source. Portions of the antibody absorbed with cells of the 46,X,dic(Y) male were found to be less reactive than portions absorbed with cells of the normal XY male, for all numbers of cells and both dilutions of plated antigen. The results, quantified in an electronic optical density reader, imply presence of excessive H-Y in cells of the 46,X,dic(Y) male, and suggest presence of a genetic determinant of H-Y on Yp or proximal Yq near the centromere.

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.

Detection at amniocentesis of a maternally inherited X;Y translocation

G banded chromosomal analysis of cells from a routine amniocentesis revealed a Y to X translocation in the fetus. The same unbalanced translocation was found in the mother who was disproportionately short. H-Y antigen titers in the mother were intermediate and steroid sulfatase activity was in the normal female range. At birth the baby exhibited few dysmorphic features but appeared to have short limbs.

Study of H-Y antigen in abnormal sex determination with monoclonal antibody and an ELISA

A newly developed enzyme-linked immunosorbent assay (ELISA) has been applied to the study of H-Y antigen in cases of XY, XYY, and X,dicY gonadal dysgenesis, testicular feminization syndrome, XXXXY syndrome, and XX true hermaphroditism. Monoclonal H-Y antibody was absorbed with cells from each of eight patients and from normal male and female controls, and then reacted with a plated antigen source in a system subsuming the addition of biotinylated secondary antibody, avidin-biotin-enzyme complex and substrate, and thereby the generation of a color. Positive absorption decreased the reaction, and this allowed sensitive measurement of H-Y phenotype in an electronic optical density reader. The ELISA obviates many of the technical difficulties encountered in complement-mediated cytotoxicity systems and can be used in the study of clinical cases of aberrant sex determination and in the evaluation of current models of the genetics of sex determination.

Serologically H-Y antigen-negative XO mice

In a series of six independent experiments organ homogenates of 35 mice of the XX, XO or XY sex chromosome constitutions were absorbed using three different anti-H-Y antisera raised in inbred female LEW rats. Residual activities of absorbed antisera were tested in the Raji cell, complement-dependent, cytotoxicity test. Homogenates of various tissues, including the gonads, of XX and XO females were equally unable to absorb H-Y antibodies, indicating that tissues of these mice do not carry the H-Y antigen. In contrast, XY male homogenates fully absorbed H-Y antibodies of antisera at concentrations of 1/2 to 1/4. We discuss our findings with special attention to the problem of the existence of one or more H-Y antigens and, to the genetic regulation of the expression of this antigen.

46,XY gonadal dysgenesis: is oncogenesis related to H-Y phenotype or breast development?

Among women with 46,XY gonadal dysgenesis, there is a high incidence of gonadal tumors. Because of evidence of a connection between occurrence of those tumors, H-Y phenotype, and breast development, we surveyed 55 cases of 46,XY gonadal dysgenesis and 12 related cases involving chromosomal and/or skeletal abnormalities. Our survey, including three new cases presented here, indicates that H-Y phenotype but not breast development may be related to the development of the gonadoblastoma-dysgerminoma. Thus among women with 46,XY gonadal dysgenesis, there are H-Y- and H-Y+ classes, but gonadal tumors are found almost exclusively in the H-Y+ class. Yet one of our patients may represent an exception to the association of H-Y+ phenotype and gonadal tumors in this syndrome.

H-Y typing in the ELISA

In a series of quantitative absorptions, biotin-conjugated monoclonal H-Y antibody was reacted with a plated source of H-Y antigen in the ELISA. H-Y was demonstrated in testis supernatant fluid of the mouse in this system, and in cells from males of the mouse, bovine and human and females of the chicken, thereby confirming its evolutionary persistence, and underscoring its presumptive role in the primary determination of vertebrate sex.

Male sexual differentiation in mice lacking H–Y antigen

The sexual phenotype of an adult mammal depends on whether the fetal gonad has differentiated as a testis or as an ovary. Because individuals of XY or XXY sex chromosome constitution develop as males, while XX and XO individuals develop as females, the presence of a Y chromosome seems normally to be required for testis differentiation and its absence to be necessary for differentiation of an ovary. The nature of the hypothetical Y-dependent substance responsible for masculinization of the indifferent gonad has been a matter for debate. A male-specific transplantation antigen, H-Y, has been known for many years and more recently a serologically detected antigen, also male-specific, has been reported. Those who believe that the two are antigenically distinct refer to the latter as SDM (serologically detected male) antigen, but many refer to both as H-Y antigen. The hypothesis that H-Y is itself the Y-dependent testis inducer, although supported by little or no direct evidence, is economical and hence attractive. H-Y antigen is frequently stated to be the substance responsible for primary sex determination (for example, see ref. 11). We report here that H-Y is absent from certain mice that develop testes and are of indisputably male phenotype, hence this transplantation antigen is unlikely to be responsible for testis determination.

Gonadal tumors in patients with gonadal dysgenesis and sex chromosomal rings and fragments

Patients with female phenotypes and dysgenetic gonads harboring testicular tissue have a markedly increased risk of developing gonadal tumors. Cytogenetic demonstration of Y chromatin is the currently accepted criterion for performing prophylactic gonadectomies in these women. We studied four patients with dysgenetic gonads containing either testicular tissue or germ cell tumors. All had small sex chromosomal fragments which could not be characterized by conventional cytogenetic studies. Clinical features, DNA replication studies, and immunologic assays of Xga and H-Y antigens failed to correlate consistently with the gonadal histology. We recommend prophylactic gonadectomies and subsequent hormone replacement in all patients with female phenotypes, gonadal dysgenesis, and cytogenetically indeterminate sex chromosomal fragments.

Protein A radio-assay of H-Y antigen on human leukocytes using mouse and rat antisera and monoclonal antibodies

The presence of H-Y antigen on human leukocytes was investigated using a protein A radio-assay. H-Y antigen could be demonstrated on male cells using either conventional H-Y antisera produced in mice and rats, or monoclonal H-Y antibodies. With mouse antiserum and IgG-type monoclonal antibody the reaction was male-specific using a single antibody. The reaction obtained with rat antiserum was enhanced by the application of a second antibody (rabbit anti-mouse IgG). This technique provides a rapid, simple, objective, and semiquantitative method for the determination of cellular H-Y antigen, the results being expressed as radioactivity bound to the test cells and thus being independent of human observation. It requires only 10-20 ml of blood and small quantities of antiserum or antibody.

H-Y antigen negativity associated with a normal male phenotype

The 46, XY, 45, X mosaicism is a complement found only once among 39,557 males at birth [18]. The spectrum of phenotypes associated with this mosaicism is continuous ranging from female phenotype with or without Turner syndrome, to mixed gonadal dysgenesis, hermaphroditism, or occasionally almost normal males [24]. In such mosaicism the Y chromosome is usually rearranged: mainly i(Y) and dic(Y) but also del(Y) and r(Y). In a few cases the cell line with 46 chromosomes contains a minute marker which was assumed to be a Y-fragment (Y-f) or a del(Yq) because of the presence of testicular tissue in subjects with sexual ambiguity [20]. We now report the case of a normal but sterile man with a 45, X/46, X, Y-f caryotype who is HY antigen-negative.

Presence of H-Y antigen in female patients with sex-chromosome mosaics and absence of testicular tissue

H-Y antigen was tested in five women with sex chromosome mosaicism and gonadal streaks. Three patients had a 45,X/46,XY or 46,X,der(Y) and two a 45,X/46,X, der(X) chromosome constitution. All patients were H-Y antigen positive. Lack of testis differentiation in these women may be explained by subthreshold expression of H-Y antigen, different H-Y antigen molecules, and/or different tissue distribution of the chromosome mosaicism.

The H-Y antigen and its functions: a review and a hypothesis

Having reviewed the status of H-Y as the sex-determining antigen concerned with the differentiation of the dominant gonad, we consider some of the problems deriving from the tests for this antigen, and from their application to the study of natural experiments. To reconcile the results of these studies with the alleged influence of H-Y on gonadal development, we propose and discuss a hypothesis on the genetic control of the synthesis of this antigen. This states that an autosomally-coded, positively cross-reacting precursor is rendered biologically active by a Y-chromosomal gene, and transformed (in a dose-dependent manner) into a biologically inactive, antigenically negative substance under the influence of an X-chromosomal gene.

H-Y antigen in XO mice

We examined the expression of H-Y antigen in 14 XO female mice using three monoclonal H-Y-specific antibodies. We found that spleen and liver cells from XO mice removed the reactivity of these antibodies at the same efficacy as XY cells. However radiobinding assays on cultured XO cells suggested a qualitative or quantitative difference between XO and XY cells. In cell-mediated cytolysis (CMC), H-Y-specific reactivity was observed when XO fibroblasts were used as targets, but no reactivity was observed when XO concanavalin A (Con A) blasts were used as targets. We concluded from these studies that XO mice do express H-Y antigen, detected both by serologic assays and cell-mediated assays.