[Mechanism of immune response inhibition during parabiosis of animals of different ages].

Experiments were made of CBA mice aged 4-5 and 24-27 months under 2-months heterochronic parabiosis to determine the primary immune response to administration of sheep red blood cells. One and three months after parabionts separation the magnitude of the immune response did not significantly differ from that of non-separated parabionts and approximated the immune response in old mice. Splenectomy in old partners did not remove the inhibitory effect on young parabionts. X-Ray irradiation of old parabionts 3-5 days after coupling with young ones caused an appreciable recovery of immune function both in old and young partners.