CD59 (homologous restriction factor 20), a plasma membrane protein that protects against complement C5b-9 attack, in...

Area of Science:

• Immunology
• Pathology
• Cardiovascular Research

Background:

• Blood cells express CD59 (homologous restriction factor 20), inhibiting complement C5b-9 membrane insertion.
• Membranous C5b-9 has been detected in human atherosclerotic lesions.
• The cellular distribution of CD59 in these lesions was previously unknown.

Purpose of the Study:

• To investigate the presence and cellular localization of CD59 in human atherosclerotic lesions using immunohistochemistry.
• To determine if CD59 expression correlates with complement deposition in lesions.

Main Methods:

• Immunohistochemistry was performed on human atherosclerotic lesion specimens.
• A monoclonal anti-CD59 antibody was used for staining.
• Co-localization studies were conducted with markers for macrophages (CD14), T lymphocytes (CD7), endothelial cells (factor VIII related antigen), and smooth muscle cells (alpha actin, muscle myosin).

Main Results:

• CD59 staining was observed in nearly all lesion specimens, co-localizing with macrophages, T lymphocytes, endothelial cells, and smooth muscle cells.
• Endothelial cells showed more intense CD59 staining than other cell types.
• CD59 expression was variable, with some smooth muscle cells negative and some areas exhibiting C5b-9 deposits despite CD59 presence.

Conclusions:

• CD59 (HRF20) is constitutively expressed on endothelium and its expression is regulated in smooth muscle cells within atherosclerotic lesions.
• The findings suggest that complement C5b-9 attack in atherosclerotic lesions is most likely to occur on smooth muscle cells.
• CD59 distribution indicates a complex interplay between complement regulation and cellular components in atherogenesis.