Acute graft versus host disease reaction occurs in all except –
**Core Concept**
Acute graft-versus-host disease (GVHD) is a major complication of allogeneic hematopoietic stem cell transplantation, where donor immune cells attack the recipient's tissues. It occurs due to the recognition of recipient antigens as foreign by the donor T cells, leading to an immune response.
**Why the Correct Answer is Right**
Acute GVHD primarily affects the skin, liver, and gastrointestinal tract. The pathogenesis involves the activation of donor T cells, which then release cytokines and chemokines, causing inflammation and tissue damage. The recipient's immune system is unable to control the donor T cells, leading to a severe immune response.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because acute GVHD is indeed a well-known complication of allogeneic hematopoietic stem cell transplantation.
**Option B:** This option is incorrect because chronic GVHD is a separate entity, characterized by a more indolent course and different clinical manifestations.
**Option C:** This option is incorrect because graft-versus-leukemia (GVL) is a beneficial effect of GVHD, where the donor immune cells attack and eliminate the recipient's malignant cells.
**Clinical Pearl / High-Yield Fact**
A key factor in the development of acute GVHD is the degree of human leukocyte antigen (HLA) mismatch between the donor and recipient. A higher degree of HLA mismatch increases the risk of acute GVHD.
**Correct Answer:** D. Chronic graft-versus-host disease reaction is not an acute reaction.