This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
[{'content': 'Acute GVHD is caused by- \nSelect and explain. \nA. B lymphocyte, B. T lymphocyte, C. Macrophage, D. NKcell', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Graft\xa0versus host (gvh) diseases\n\nGraft\xa0versus host disease occurs in any situation\xa0in which immunologically competent cells or their\xa0precursors are transplanted into immunologically crippled patients\xa0and the transferred cells recognize\xa0alloantigens\xa0in the host.\nGraft\xa0versus host disease occurs most commonly in the setting of allogeneic bone marrow transplantation but may also follow transplantation\xa0of solid organs rich in lymphoid cells (e.g. the liver) or transfusion of\xa0unirradiated blood.\nRecipients of bone marrow transplants are immunodeficient because of either their primary\xa0disease or\xa0prior treatment of the disease with drugs or irradiation.\nWhen such recipients receive normal bone marrow cells from allogeneic donors, the immunocompetent, T cells present in the donor marrow recognize the recipient’s HLA antigen as a foreign antigen\xa0and react\xa0against them. Both CD4+ and CD8+\xa0T cells recognize and attack host tissues.\nIn clinical practice,\xa0GVH can be so severe that bone marrow transplants are done only between HLA\xa0matched donor and recipient.\n\nPathological changes in GVH diseases\n\nThere are three principal target tissues\xa0affected in GVHD: Skin, liver, and gut. GVHD may be acute or\xa0chronic:-\n\nA) Acute GVHD\n\nAcute GVHD occurs within 100 days (usually 10-50 days) of bone marrow transplantation. The\xa0manifestations\xa0of acute GVHD are\n\n1. Skin\n\nIt is the most commonly affected tissue\xa0in acute GVHD. There is generalized rash\xa0(maculopapular).\n\nHistological findings are\ni. Perivascular mononuclear infiltrates.\nii. Vacuolar degradation of dermo-epidermal junction\niii. Dyskeratotic\xa0or eosinophilic bodies in the epidermis.\niv. Epidermolysis & bullae.\nv. Denudation\xa0of epidermis (separation\xa0of epidermis from dermis),\n2. Gut\n\nThe primary clinical manifestation\xa0of gut GVHD is diarrhoea and abdominal pain. There is\xa0lymphocytic\xa0infiltrate at the crypts with accompanied necrosis and drop out of crypt cells.\n\n3. Liver\n\nLymphocytic\xa0infiltrates in the interlobular and marginal bile ducts are characteristic\xa0histopathologic findings. This results in hepatitis\xa0with necrosis of hepatocytes and bites duct\xa0epithelial cells. There is inflammation\xa0of the parenchyma and portal tracts. These findings\xa0lead to a clinically identifiable cholestatic\xa0picture.\n\nB) Chronic GVHD\n\nIt occurs after 100 days of bone marrow transplantation. Manifestations\xa0are:-\n\n1. Skin\n\nExtensive cutaneous injury, with the destruction of skin appendages and fibrosis of the dermis.\n\n2. Gut\n\nDamage to GIT may result in necrosis, ulceration\xa0fibrosis and strictures.\n\n3. Liver\n\nThe findings of liver damage are i) Portal tract inflammation ii)\xa0Selective bile duct destruction\n\niii. Endothelitis of the portal vein and hepatitis vein radicles, in which a subendothelial\xa0lymphocytic\xa0infiltrate lifts the endothelium from its basement membrane.\niv. Intrahepatic\xa0cholestasis', 'role': 'assistant'}]