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Immunoglobulin G independent activation of the classical complement pathway by monosodium urate crystals

P C Giclas, M H Ginsberg, N R Cooper

    The Journal of Clinical Investigation
    |April 1, 1979
    PubMed

    Insights

    Monosodium urate crystals activate the complement system

    Area of Science:

    • Immunology
    • Biochemistry

    Background:

    • The complement system is a crucial part of innate immunity.
    • Complement activation can be triggered through various pathways, including the classical pathway.

    Purpose of the Study:

    • To investigate the effect of monosodium urate crystals on the human complement system.
    • To determine the specific complement pathway activated by monosodium urate crystals.

    Main Methods:

    • Human serum was incubated with monosodium urate crystals.
    • Complement component levels (CH50, C1, C4, C3) were measured.
    • The binding and activation of complement component C1 by urate crystals were assessed.

    Main Results:

    • Monosodium urate crystals significantly reduced CH50 activity.
    • Depletion of C1, C4, and C3 indicated classical pathway activation.
    • Urate crystals bound to and activated isolated C1 complex (C1qrs).

    Conclusions:

    • Monosodium urate crystals activate the classical pathway of the complement system.
    • This activation is independent of Fc-mediated binding, suggesting a direct interaction.

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