Enzyme-linked immunosorbent assay (ELISA) for detecting antisperm antibodies in mice with testicular autoimmunity

Tissue microcircumstances for leukocytic infiltration into the testis and epididymis in mice

Spermatozoa do not appear in the seminiferous epithelium until puberty, when immune tolerance has already been established. Therefore, they contain various autoimmunogenic materials which are recognized as foreign by the self immune system. However, the testis and epididymis are known as immunologically privileged organs. In particular, the blood-testis barrier (BTB) formed by Sertoli cells and the blood-epididymal barrier formed by epididymal epithelial cells protect autoimmunogeneic spermatozoa from attack by the self immune system. The immune privileged circumstances in the testis and epididymis have been demonstrated by many studies to involve a local transplantation system. We review here the immune privileged status of these organs from the viewpoint of induction of inflammatory cell responses in mice. The testicular interstitium in mice is resistant to vasculitis, lymphangitis, spermatic granuloma and polymorphonuclear cell infiltration: however, the epididymal interstitium is vulnerable to them. Therefore, the testicular tissue outside BTB is also protected from inflammatory cell infiltration, although many resident macrophages are normally present in the testis. In sharp contrast, subcutaneous injection of viable syngeneic testicular germ cells (TGC) alone induces autoimmune orchitis with no involvement of the epididymitis in mice. In the testes of TGC-immunized animals, severe lymphocytic infiltration with aspermatogenesis was seen in spite of no use of adjuvants. Unexpectedly, injections of viable epididymal spermatozoa (ES) did not evoke any autoimmune inflammation in the epididymides. Therefore, the testis rather than the epididymis may easily become an unprivileged organ as to autoimmunity under some special conditions.

An increase of B cells in the tumor-bearing state has the potential to induce anti-tumor immunity

We investigated the role of an increased amount of B cells in the tumor-bearing state. The proportion of B cells increased concomitantly with tumor development in the regional lymph nodes (LN) of BALB/c mice bearing Meth A fibrosarcoma (Meth A). Tumor development was accompanied by an increased level of IgG antibodies against Meth A. CD4+ T cells of the regional LN in the early tumor-bearing stage produced significant levels of interferon-gamma and interleukin-4 in response to in vitro stimulation with coated anti-CD3 monoclonal antibody, whereas such capacities decreased in the late tumor-bearing stage. In a tumor-neutralizing assay, the growth of Meth A was significantly suppressed by a co-inoculation with splenic B cells from BALB/c mice in the late tumor-bearing state. This suppression of Meth A growth was tumor-specific and was abolished by the in vivo depletion of either CD4+ or CD8+ T cells. These findings thus suggest that tumor development was accompanied by an increase of B cells and tumor-specific IgG production, but such kinetic changes were not the result of a preferential activation of Th2 type CD4+ T cells. Furthermore, our results indicate that the increase of B cells in the tumor-bearing state has the potential to induce anti-tumor-specific T cell immunity.

Generation and characterization of a continuous line of CD8+ suppressively regulatory T lymphocytes which down-regulates experimental autoimmune orchitis (EAO) in mice

We have previously shown that two injections with viable syngeneic testicular germ cells (TC) alone developed experimental autoimmune orchitis (EAO) in C3H/He mice, and that the induction of antigen-specific tolerance in this EAO model is associated with the generation of antigen-specific suppressively regulatory T (Ts) cells. For the elucidation of the nature of these Ts cells, a murine Ts cell line (designated Ts-A) was established. This line was generated from the spleen cells of C3H/He mice which had received three i.v. injections of a soluble (deaggregated) form of murine testicular antigen (mTA), followed by the repeated selection of these spleen lymphocytes in vitro by stimulation with mTA. Adoptive transfer of Ts-A cells into naive syngeneic mice immediately before the first TC injection was found to downgrade EAO in actively immunized recipients. The transferred Ts-A cells significantly inhibited the cellular immune response to TC in the recipients in an antigen-specific manner, but these cells had no inhibitory effect on the humoral immune response to TC. This line could also inhibit in vitro syngeneic TC-driven proliferation of orchitogenic lymphocytes. Surface phenotype of this line was CD8+, CD4-, Thy-1.2+, CD3+, and TCR alpha beta+. These findings may suggest an in vivo role for suppressively regulatory lymphocytes, capable of inhibiting helper T cells, in the regulation of EAO.

Suppression of efferent limb of testicular autoimmune response by a regulatory CD4+ T cell line in mice

A murine T cell line (designated as C.Ts) as a mediator of suppression of experimental autoimmune orchitis (EAO) was established. The method of establishment of C.Ts cell line was preparing spleen cells from C3H/He mice hyperimmunized with testicular germ cells (TC) and the repeated selection of the lymphocytes in vitro by stimulation with mouse testicular antigens (mTA). The C.Ts cells were Thy1.2+, surface immunoglobulin-, CD3+, CD4+ and CD8-. The cells could suppress the induction of EAO when transferred into actively EAO-sensitized mice only at the pre-clinical stage of the disease (efferent limb of the autoimmune response). The transferred C.Ts cells significantly inhibited both cellular and humoral immune responses to TC in the recipients in an antigen-specific manner. The disease suppression by C.Ts cells was found to depend upon their cell number, and their suppressive activity was markedly augmented by in vitro stimulation with mTA.

Inhibition of a novel model of murine experimental autoimmune orchitis by intravenous administration with a soluble testicular antigen: participation of CD8+ regulatory T cells

Recently, we established a novel murine model of experimental autoimmune orchitis (EAO) in C3H/He mice by means of two sc injections of 1 x 10(7) viable syngeneic testicular germ cells (TC) without the use of any adjuvants. Using this model, an effective and reproducible system of immunoregulation in EAO was developed. The induction of this EAO was suppressed by pretreatment with five iv injections of a soluble (deaggregated) form of murine testicular antigen (mTA). The antigen, mTA, was prepared by acid extraction and ammonium sulfate precipitation of defatted testes and epididymides. The development of EAO and relevant delayed-type hypersensitivity was suppressed in an antigen-specific fashion, but anti-TC antibody formation was not affected. A single dose of cyclophosphamide at 2 days after the tolerogenic regime abrogated the unresponsiveness to EAO. Three doses of recombinant interleukin 2 at every other day starting on the next day of the last pretreatment did not overcome the unresponsiveness to EAO. CD8+ T cells isolated from the spleen of deaggregated mTA-pretreated animals could adoptively transfer suppression against EAO into naive recipients, whereas CD4+ T cells failed to transfer the suppression.

Testicular lesions and lymphocyte subpopulations in rats immunized with a soluble fraction of testicular homogenate

A soluble fraction obtained from a testicular homogenate by precipitation with ammonium sulphate (ASPM) was emulsified with Freund's complete adjuvant (CFA) and injected into Wistar rats. At 50 days after the first immunization (total of three injections) the animals had developed moderate and multifocal testicular damage, characterized mainly by sloughing of the seminiferous epithelium. A delayed-type hypersensitivity response and circulating antibodies to ASPM were detected at different times with maximum levels at 50 days. The addition of Bordetella pertussis to the immunization did not increase the severity of the lesion but augmented the cellular and humoral immune response to ASPM. The phenotypic characterization of cells present in the lymph nodes draining from the site of immunization in animals injected with CFA alone (control group) revealed an increase in CD8+ T-cells and a low CD4/CD8 ratio. Conversely, rats immunized with CFA plus ASPM (experimental group) exhibited testicular damage and showed a significant decrease in CD8+ cells with a normal CD4/CD8 ratio. In conclusion, rats immunized with a testicular antigen developed focal aspermatogenic lesions and a concomitant specific immune response as well as lymph-node cell variations focused apparently on the CD8+ T-cell subpopulation.

A new murine model of autoimmune orchitis induced by immunization with viable syngeneic testicular germ cells alone. I. Immunological and histological studies

Experimental autoimmune orchitis (EAO) was produced in C3H/He mice with as high as 100% incidence by two or three s.c. injections of 1 x 10(7) viable syngeneic testicular germ cells (TC) without resorting to adjuvants, Bordetella pertussis vaccine, or other immunological manipulations. On day 40 after the first injection of TC, the lesions induced were characterized by interstitial infiltration of inflammatory cells and severe hypospermatogenesis in the testis with resulting whole organ atrophy and, in contrast, by a complete lack of epididymitis. Immunological studies revealed that this form of immunization caused both delayed-type hypersensitivity and humoral antibody responses to syngeneic TC. We compared the susceptibilities to the induction of this type of EAO among six different strains of inbred mice comprising A/J, AKR, BALB/c, C3H/He, C57BL/6 and DBA/2 mice. All strains except for DBA/2 mice developed lesions of EAO to a greater or lesser extent, and severe disease was induced with high frequency in two strains, C3H/He and A/J. As this murine model of EAO can be induced without the use of Freund's complete adjuvant and B. pertussis vaccine, it is simply 'autoimmune' in nature and may provide new ways for further investigation into the immunological mechanisms which regulate deleterious autoimmune reactions to germ cell antigens leading to the male infertility.