HLA – B5 is associated with
**Core Concept**
HLA-B5 is a specific type of human leukocyte antigen, which is a protein on the surface of white blood cells that plays a crucial role in the immune system. HLA-B5 is associated with several diseases and conditions due to its involvement in the presentation of peptides to T-cells, which can trigger an immune response.
**Why the Correct Answer is Right**
HLA-B5 is particularly associated with an increased risk of developing certain infections and autoimmune diseases, such as leprosy and rheumatoid arthritis. This is because the specific peptide-binding groove of HLA-B5 can present certain antigens to T-cells in a way that triggers an excessive or inappropriate immune response. The association between HLA-B5 and these diseases is thought to be due to the unique structure of the HLA-B5 protein, which allows it to bind to specific peptides that are presented to T-cells.
**Why Each Wrong Option is Incorrect**
**Option A:** HLA-A2 is associated with an increased risk of developing certain viral infections, such as HIV and HLA-A2 is not associated with HLA-B5.
**Option B:** HLA-DRB1 is associated with an increased risk of developing rheumatoid arthritis, but it is not the specific HLA type associated with the condition in question.
**Option C:** HLA-C is associated with an increased risk of developing certain autoimmune diseases, but it is not specifically linked to HLA-B5.
**Clinical Pearl / High-Yield Fact**
It's essential for clinicians to be aware of the specific HLA associations with various diseases to provide targeted treatment and preventive measures for patients at increased risk.
**Correct Answer:** D.