Immunological effects of orchidectomy.

Orchidectomy caused a non-specific increase of immunological reactivity in mice evidenced by accelerated rejection of skin allografts, increased response to oxazolone and sheep erythrocytes. These changes were associated with an increase of thymic size. The response to pneumococcal polysaccharide, which depends upon B-cells, was not increased. Orchidectomised mice showed protection against induced methylcholanthrene sarcomas and transplantable tumours; tumours which are not obviously hormone dependent.