[Primary immune response in parabionts of different ages]

Potential mechanisms of aging of the immune system were studied in experimental heterochronic parabiosis of CBA mice. Vascular anastomoses were formed between parabionts thus providing an exchange of the humoral and cell factors and repopulation of lymphoid organs by the partner cells. Investigation into the primary immune response to sheep red blood cells has shown the suppression of antibody production in young partners to be the result of the old body influence. The effect of stimulation of the old immune system by the young animal, however, was only slightly pronounced. It is suggested that the factors actively suppressing the immune response of the young animal may exist in the old body.