John was given ATG in addition to steroids to control acute

John was given ATG (in addition to steroids) to control acute GVHD. Describe two different strategies to achieve in vivo depletion of T lymphocytes (in humans or mice).

Solution

Antithymocyte globulin (ATG) targets many antigens which are present in diversified classes of immune system cells. These antigens of immune cells are mainly involved cell adhesion,cell traafficking, immune responses and many pathways. ATG binds to these antigens present on immune cells and causes complement mediated lysis of cells. In peripheral lymphoid tissue, these ATG antibodies act as opsonin therby enhancing phagocytosis by phagocytes.

Steroids exert their immunosuppressive effect by modulating transcription of many genes of leakocytes and the genes they regulate are wide in nature.

However, it is in practice that steriods are given primarly as an immunosupressor after bone marrow transplantation (BMT). If it does not solve the problem, then ATGs are given as a secendary treatment.