Differential expression of the complement regulatory proteins in the human eye

Area of Science:

• Ophthalmology
• Immunology
• Cell Biology

Background:

• Complement activation products are present in the human eye during infection/inflammation.
• Host protection against self-tissue attack during complement activation is mediated by three membrane-bound complement regulatory proteins: membrane cofactor protein (MCP, CD46), decay accelerating factor (DAF, CD55), and membrane attack complex inhibiting protein (CD59).

Purpose of the Study:

• To analyze the expression of MCP, DAF, and CD59 in the normal human eye.

Main Methods:

• Human eye tissues were sectioned using a cryostat.
• Polyclonal and monoclonal antibodies against MCP, DAF, and CD59 were utilized for staining.
• Control stains included nonrelevant antibodies, normal rabbit serum, and omission of primary/secondary antibodies.

Main Results:

• All three complement regulatory proteins (MCP, DAF, CD59) showed differential expression in the human eye.
• MCP was strongly expressed in the corneal epithelium and weakly in corneal keratocytes and photoreceptor cells.
• DAF was highly expressed in the corneal epithelium and ciliary body, with moderate expression in corneal stroma and iris.
• CD59 demonstrated strong expression across the corneal epithelium, corneal stroma, iris, choroid, and all retinal layers, with moderate expression in the ciliary body.

Conclusions:

• The presence of MCP, DAF, and CD59 in the human eye indicates a regulatory system protecting ocular cells from complement-mediated destruction.
• Further research is needed to determine specialized functions of these proteins, particularly CD59 due to its widespread retinal expression.