Immune adherence in renal glomeruli. Complement receptor sites on glomerular capillary epithelial cells

Area of Science:

• Nephrology
• Immunology
• Cell Biology

Background:

• Recent reports suggest complement component C3 receptor sites in human renal glomeruli.
• The specific cell type bearing these receptors in the glomerulus remained unidentified.

Observation:

• Human glomerular capillary epithelial cells were examined using EAC complexes and fluoresceinated zymosan-C3 (ZC3b).
• Microscopy techniques including scanning electron microscopy confirmed immune adherence of EAC indicator cells to these epithelial cells.

Findings:

• Glomeruli and glomerular epithelial cells bind EAC1423b and ZC3b, but not earlier complement components, indicating C3b mediates the immune adherence.
• Diseased renal biopsies showed immune-adherence negative sclerotic glomeruli and proliferative lesions.
• An inverse relationship between C3 deposits and immune adherence was less evident than previously reported.

Implications:

• Glomerular C3b receptors may facilitate the binding of immune complexes to the subepithelial surface of glomerular capillaries.
• The identified C3 receptors in human glomeruli may not be universally present across all vertebrate species, warranting further investigation.