Human leukocyte antigen (HLA) which plays an impoant role in graft rejection is present on chromosome:
**Core Concept**
The Human Leukocyte Antigen (HLA) system is a group of genes that play a crucial role in the immune system by coding for proteins responsible for the recognition of self and non-self cells. The HLA system is located on the short arm of chromosome 6 and is essential for the proper functioning of the immune response.
**Why the Correct Answer is Right**
The HLA genes are located in a region of chromosome 6 known as the Major Histocompatibility Complex (MHC). The MHC region contains multiple genes that code for different HLA proteins, which are expressed on the surface of white blood cells and are involved in the presentation of peptide fragments to T-cells. This process is critical for the recognition of foreign substances and the activation of an immune response. The HLA system is responsible for graft rejection because it recognizes the HLA proteins on foreign cells as non-self and mounts an immune response against them.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the HLA system is not located on chromosome 1.
* **Option B:** This option is incorrect because the HLA system is not located on chromosome 9.
* **Option C:** This option is incorrect because the HLA system is not located on chromosome 10.
**Clinical Pearl / High-Yield Fact**
The HLA system is a critical component of the immune response, and its proper functioning is essential for preventing graft rejection. Understanding the HLA system is crucial for transplant medicine, and genetic matching between donor and recipient is essential to minimize the risk of rejection.
**Correct Answer:** C. 6 (the correct answer is missing, assuming it's the complete answer)