Immunological studies on the rat thymectomized in adult life

Abstract

Rats thymectomized in adult life showed no decrease in ability to produce circulating antibodies to sheep erythrocytes and tetanus toxoid even when tested 270 days after thymectomy. From 120 days after thymectomy onwards allogeneic skin-graft rejection times were increased to about twice that found in control animals.

Rabbit anti-rat lymphocyte serum (ALS) was given to non-thymectomized rats and, at varying intervals after thymectomy, to rats which had been thymectomized in adult life. Non-thymectomized rats so treated showed no decrease in their ability to reject allogeneic skin grafts or to produce antibodies to sheep erythrocytes. In contrast there was a significant depression of the immune response of all thymectomized rats given ALS. Allogeneic skin graft rejection times were longer in animals given ALS 180 and 240 days after thymectomy than in any of the other groups of animals.

There was a significant depression in the ability of animals given ALS 240 days after thymectomy to produce antibody in response to the second of two doses of tetanus toxoid injected 7 weeks after the administration of ALS. All other animals behaved normally when immunized in this way.