Ontogeny of the third component of complement of Japanese quails

Ontogeny of quail complement was examined in terms of serum C3 level, cytolytic activity of total complement, functional activity of C3 via the classical pathway (CCP) and an alternative route (ACP), and the distribution of C3-bearing cells. In serum, C3 was detected from 7-day-old embryos by rocket immunoelectrophoresis. Thereafter, its concentration increased rapidly and reached the adult level at 4-5 weeks of age. Total activities of serum complement via CCP and ACP, both of which were assayed by cell lysis, were detected first in 10-day-old embryos, and increased sharply after hatching, reaching the maximum level at 5 weeks of age. Deposition of C3 on the cell surface via CCP and ACP was also clearly demonstrated from 10-day-old embryos by haemagglutination and immunofluorescence techniques, respectively. By an immunofluorescence technique using anti-quail C3 monospecific serum, cells belonging to the reticuloendothelial system were indicated to serve major sites for the synthesis of C3 during ontogenesis.