Differential cell surface distribution of adhesion molecules demonstrated by immuno-scanning electron microscopy

Area of Science:

• Dermatopathology
• Immunohistochemistry
• Cellular Biology

Background:

• Mycosis fungoides (MF) and lichenoid reaction (LR) are distinct inflammatory skin conditions with overlapping clinical and histological features.
• Understanding the molecular mechanisms underlying their pathogenesis is crucial for accurate diagnosis and treatment.

Purpose of the Study:

• To investigate the differential expression of intercellular adhesion molecule-1 (ICAM-1), leukocyte function-associated antigen-1 (LFA-1), and human leukocyte antigen-DR (HLA-DR) in MF and LR.
• To correlate these molecular findings with the characteristic histological patterns of epidermotropism and band-like infiltrate.

Main Methods:

• Scanning electron microscopy (SEM) combined with immuno-gold labeling was employed.
• Expression patterns of ICAM-1, LFA-1, and HLA-DR were analyzed on epidermal keratinocytes and dermal infiltrates in MF and LR lesions.

Main Results:

• In MF, ICAM-1 was clustered at keratinocyte junctions, and HLA-DR was continuously expressed along keratinocyte borders. LFA-1 was found on infiltrates, many co-expressing ICAM-1.
• In LR, ICAM-1 and HLA-DR were sparsely expressed on the epidermal undersurface, while infiltrates expressed LFA-1.
• Distinct ICAM-1 distribution in MF correlates with LFA-1-bearing cell migration into keratinocyte interspaces (epidermotropism) and aggregation (microabscess formation).

Conclusions:

• Differential expression of ICAM-1 and HLA-DR molecules contributes to the distinct histological features observed in MF and LR.
• The findings provide a molecular basis for understanding epidermotropism in MF and the band-like infiltrate in LR.
• Targeting these adhesion molecules may offer therapeutic potential in managing these skin conditions.