A marked lymphocyte depletion and a striking impairment of their capacity to form antibodies against sheep erythrocytes was shown by outbred Swiss albino mice thymectomized or sham-thymectomized at birth and later treated with anti-lymphocyte serum.
Ninety-four per cent of allogeneic and 53% of heterogeneic skin grafts applied to the former, and 63% and 0% of those applied to the latter, survived up to the time of killing, i.e. 41 days after transplantation.
The remaining allogeneic and heterogeneic skin grafts were rejected by mice belonging to both experimental groups in a minimum of 18 days and a maximum of 35 days, which is much longer than is usually required by normal recipients (allogeneic grafts = about 10–11 days; heterogeneic grafts = about 7–8 days).
Despite the severe immunological depression caused by anti-lymphocyte serum treatment, either associated or not with neonaial thymectomy, all the mice chronically exposed to casein developed amyloidosis.
The present results are in accordance with previous findings indicating that mechanisms other than immunity may be involved in the pathogenesis of amyloidosis.