Antithymocyte globulin (Atgam) is purified immune
globulin obtained from hyperimmune serum of horses
immunized with human thymus lymphocytes. It has
been used successfully alone and in combination with
azathioprine and corticosteroids to prevent renal allograft
rejection. Although it has benefits when administered
prophylactically, its use during rejection episodes
may be its greatest value.
Antithymocyte globulin binds to circulating T lymphocytes
in the blood, which are subsequently removed
from the circulation by the reticuloendothelial system.
This globulin also reduces the number of T lymphocytes
in the thymus-dependent areas of the spleen and lymph
nodes.
Since the preparations are raised in heterologous
species, reactions against the foreign proteins may lead
to serum sickness and nephritis.The concomitant use of
corticosteroids may alleviate this response.
