Studies on the prostate and testis as immunologically privileged sites

The immunology of the prostate and testis was studied by observing allograft survival in rats and by measuring humoral antibody and delayed hypersensitivity responses to tissue antigens in the rabbit. The delayed hypersensitivity response to tissue antigen(s) was definitely diminished in those organs without demonstrable afferent lymphatics (ie, prostate, anterior eye chamber) while the humoral response was unaffected. Allograft survival in the rat showed prolonged survival in the testis and anterior eye chamber with intermediate survival in the prostate and muscle and abbreviated survival of orthotopic grafts. The extraordinary incidence of prostatic carcinoma with increasing age is discussed in light of these data. The apparent paradox of the testis as an immunologically privileged site remains unexplained.