Colloid body formation in bullous pemphigoid

Area of Science:

• Dermatology
• Immunopathology
• Cell Biology

Background:

• Bullous pemphigoid (BP) is an autoimmune blistering disease.
• Characteristic immune deposits are found at the basement membrane zone in BP.
• The origin and nature of certain histological findings in BP require further elucidation.

Purpose of the Study:

• To characterize the nature of homogeneous and globular fluorescent bodies observed in bullous pemphigoid skin biopsies.
• To investigate the potential origin of these bodies from degenerated keratinocytes.
• To compare these findings with colloid bodies in other dermatoses.

Main Methods:

• Direct immunofluorescence (IF) using FITC-labelled antisera.
• Immunoperoxidase staining.
• Haematoxylin/eosin (HE) and Periodic Acid-Schiff (PAS) staining.
• Electron microscopy.

Main Results:

• Immunoglobulin and complement deposits were observed at the basement-membrane zone (BMZ).
• Homogeneous and globular fluorescent bodies were detected in the uppermost dermis and/or blisters in a subset of BP specimens.
• These bodies were PAS positive, slightly eosinophilic, and composed of microfilaments (7-8 nm diameter) under electron microscopy.
• Histological, immunohistological, and ultrastructural features were consistent with colloid bodies.

Conclusions:

• Degenerated keratinocytes in the blister roof may transform into these fibrillar bodies.
• These bodies are histologically similar to colloid bodies found in other inflammatory skin conditions.
• The findings provide insights into the cellular changes and potential pathogenetic mechanisms in bullous pemphigoid.