**Core Concept**
Dermatitis herpetiformis is a chronic skin condition characterized by blisters and intense itching, often associated with celiac disease. The exact pathogenesis of dermatitis herpetiformis involves an immune-mediated reaction to gluten, leading to the deposition of immune complexes in the dermal papillae. A strong association exists between this condition and specific human leukocyte antigen (HLA) alleles.

**Why the Correct Answer is Right**
HLA-B8 is a class I HLA allele that has been strongly associated with dermatitis herpetiformis. This association is thought to be due to the role of HLA-B8 in presenting gluten peptides to T-cells, which triggers an immune response against gluten. The presence of HLA-B8 increases the risk of developing dermatitis herpetiformis, especially in individuals with celiac disease. The genetic predisposition to this condition is complex, involving multiple genetic and environmental factors.

**Why Each Wrong Option is Incorrect**
**Option A:** HLA-A5 is not associated with dermatitis herpetiformis. While HLA-A alleles are involved in various autoimmune diseases, HLA-A5 is not specifically linked to this condition.
**Option B:** HLA-B27 is primarily associated with ankylosing spondylitis and other spondyloarthropathies, not dermatitis herpetiformis.
**Option D:** HLA-A28 is not associated with dermatitis herpetiformis. HLA-A28 is linked to several other conditions, including Graves' disease and type 1 diabetes, but not dermatitis herpetiformis.

**Clinical Pearl / High-Yield Fact**
Dermatitis herpetiformis is often treated with a strict gluten-free diet, which can lead to significant improvement in symptoms. However, the condition can be challenging to diagnose, and a skin biopsy may be necessary to confirm the diagnosis.

**✓ Correct Answer: C. HLA B8**