Immortalized Human Conjunctival Epithelial Cells Produce Functional Complement C3 and C4 Proteins

Area of Science:

• Immunology
• Ocular Surface Biology

Background:

• The ocular surface is protected by the innate immune system.
• The complement system plays a crucial role in innate immunity.

Purpose of the Study:

• To determine if human conjunctival epithelial (HCjE) cells produce complement proteins C3 and C4.
• To assess the functional capacity of HCjE cells in complement activation.

Main Methods:

• Enzyme-linked immunosorbent assay (ELISA) was used to quantify C3 and C4 levels in HCjE cell supernatants and lysates.
• Complement activation was assessed by measuring soluble C5b-9 formation after stimulation with heat-aggregated IgG.

Main Results:

• Differentiated HCjE cells showed significantly higher C3 production in supernatants and lysates compared to undifferentiated cells.
• C4 levels increased in supernatants but remained relatively unchanged in lysates.
• Soluble C5b-9 was detected in HCjE cell lysates, indicating complement-generating capacity.

Conclusions:

• HCjE cells produce C3 and C4, contributing to the ocular complement system.
• The production of C3 and C4 by HCjE cells supports the formation of C5b-9, confirming their biological activity.
• These findings suggest HCjE cells may produce the entire complement cascade (C1-C9).