Experimental testicular teratoma promotes formation of humoral immune responses in the host testis

The testis is an immunologically privileged site. Very little is known abou t the factors regulating formation of immune responses elicited by a neopla sm in the testis. We have studied the immune response of the host testis ag ainst experimental testicular teratoma in mouse by localizing adhesion mole cules (CD106, CD54, CD49d/CD29, CD44, CD18, CD8 and CD4), cytokines (IL-2, IL-4, IL-6, IL-10 and IL-12), T-cell costimulators (CD80, CD86) and the lip id antigen presenting molecule CD1d in the testis of 129/SvJ mice with and without experimental testicular teratoma. The testicular teratomas were ind uced by grafting male gonadal ridges from 12-day-old 129/SvJ mouse Fetuses into testes of adult mice from the same strain. The tumors cultured intrate sticularly for 2, 3, 4 and 8 weeks (three animals per time point) were used for immunocytochemistry. CD1d was detected in Sertoli cells and in some de generated tubules of the host testis surrounding the graft. In the tumor, C D1d was detected in glandular epithelia, smooth muscle and in thin fibers o f neural origin. IL-2 was observed in some blood vessels of the host testis and of the tumor and in occasional cell infiltrates around these vessels. Some tubular structures of the tumor were also positive for IL-2. IL-6 was detected in Sertoli cells of the normal testis and in Sertoli cells and in solitary interstitial cells as well as in the walls of some blood vessels o f the host testis. The reaction for IL-6 was more prominent in the tubules apparently damaged by the growing tumor. in the tumor IL-6 a as detected in epithelial structures, muscle cells, in thin fibers of neural origin and i n some blood vessels. IL-10 was detected in individual cells in the interst itium and in degenerating tubules of the host testis. In the tumor the epit helial structures were positive for IL-10. The interstitium of the host tes tis was positive for CD106 and the embryonic testicular cords in the graft were also positive. but the tumor was negative. CDW and CD18 were observed in some blood vessels and in degenerated tubules of the host testis. In the tumor CD44 and CD18 were occasionally observed in cartilage and in epithel ial structures. The results of the present study suggest that cytokine micr oenvironment in the testis containing neoplastic tissue promotes activation of humoral immune responses. In addition, as the damaged seminiferous tubu les expressed increased amounts of two cytokines promoting humoral immune r esponses. IL-6 and IL-10, it is possible that also in other conditions with damage to the tubules, humoral immune responses predominate. (C) 1999 Else vier Science Ireland Ltd. All rights reserved.