Suppressive effect of a mouse testicular extract on lymphocyte activation

Ipsilateral right testicular metastasis from renal cell carcinoma in a responder patient to interleukine-2 treatment

We present a case of metastatic spreading to the testicle in a 46-year-old patient with renal cell carcinoma, "clear-cell" type, during interleukin-2 combined subcutaneous plus aerosol treatment. Testicular metastasis occurred while the patient showed a response to the treatment with disappearance of lung lesions and reduction of lymph-nodes lesions. After orchiectomy with spermatic cord resection and disease re-evaluation confirming the previous response, the patient re-started immunotherapy. The contrast between systemic disease response to treatment and disease testicular progression might be explained by a relative insensitivity of the testicle to interleukin-2 immunotherapy as a result of a possible establishment of an immunosuppressive microenvironment. We believe that the rarity of this metastatic site and the intriguing possible mechanisms at its base, makes an interesting case for clinicians.

Immunotolerance induced by intratesticular antigen priming: expression of TGF-beta, Fas and Fas ligand

The authors have previously reported that an injection of S-antigen (S-Ag) into rat testes prior to immunization induces systemic tolerance (designated orchidic tolerance) and protects the animals from experimental autoimmune uveoretinitis (EAU) and that the signal for orchidic tolerance induction emigrates from the testis within a few hours after antigen priming of the testis. In order to understand the mechanism by which the signal or signal carrier is generated, they determined in this study changes in immunoreactivity for transforming growth factor-beta (TGF-beta), IFN-gamma, IL-2, Fas and Fas ligand in the testis following an injection of S-Ag. Immunoreactivity for TGF-beta increased with time, reaching a maximum in six hours and declining thereafter. The time required for the maximum expression of TGF-beta coincided well with the time-dependent profile of orchidic tolerance signal generation within the testis. Little or no immunoreactivity was observed for IFN-gamma and IL-2 in normal (control) and S-Ag-injected testes. Immunoreactivity for Fas and Fas ligand was detected both in control and experimental testes and did not change appreciably with time following Ag-priming of the testis. Fas immunoreactivity was found in spermatids and virtually absent in the interstitial tissue, while Fas ligand immunoreactivity was primarily associated with the interstitial cells such as Leydig cells. Fas ligand immunoreactivity was very weak, if any, in the germ cells and Sertoli cells. These results suggest that TGF-beta and Fas ligand expressed in MHC-positive interstitial cells may play an important role in the generation of orchidic tolerance induction signal. A preliminary study showed that splenocytes preincubated with testis extracts and S-Ag, when transferred to naive rats, induced systemic tolerance in recipient animals. Inclusion of anti-TGF-beta or a carboxyl terminal peptide of Fas in the testis extract reduced the potency of incubated splenocytes to induce systemic tolerance in recipient rats. These results indicate that generation of the orchidic tolerance signal does not require the anatomical structure of the testis but is mediated by molecular entities such as TGF-beta and Fas ligand.

Immunology of the testicular excurrent ducts

The sperm autoantigen concentration in the epididymis equals or exceeds that in the testis. This makes the epididymis a probable site of initiation of an antisperm autoimmune response. The mechanisms regulating antisperm antibody formation in the testicular excurrent ducts and some related aspects with clinical interest are reviewed.