C3 tickover activation (mechanism)

https://cyberleninka.ru/article/n/osobennosti-etiologii-i-pa...
СЗ-кнвертаза представлена комплексом C3bBbP, фиксированном на липополисахариде (ЛПС). При этом белок С3 постоянно самопроизвольно расщепляется на С3а и С3Ь - «холостая активация». В результате этого в плазме все время поддерживается невысокая концентрация С3Ь, который связывает ЛПС клеточной стенки.

https://www.frontiersin.org/articles/10.3389/fimmu.2022.9842...
Activation of the plasma complement system occurs via three main mechanisms—the lectin pathway, initiated by mannose-binding lectin; the classical pathway, initiated by the antibody; and the alternative pathway initiated by C3b binding. Additionally, autoactivation can occur via the so-called C3-tickover mechanism.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3820029/
Although the classical and lectin pathways generally are activated upon recognition of exogenous materials, the alternative pathway (AP) is constitutively active at low levels in the normal host. >b>This often is referred to as the tickover mechanism and allows the system to stay primed for rapid and robust activation.

https://books.google.ru/books?id=2AaJqNl1QIYC&printsec=front...
p. 562
C3 AND FACTOR B
The alternative complement activation pathway starts with the freely circulating inactive serum protein C3. A spontaneous low level of hydrolysis (called C3 tickover activation)...