C3 and infection: Both C3 and C5 mRNA levels were significantly upregulated after influenza infection in CD103+ DCs; C3 levels were upregulated by approximately 3-fold on day 1 post infection and 50-fold on day 3 after infection (Fig. 6B), while C5 levels were upregulated 2-fold on day 1 post infection and 5-fold on day 3 (Fig. 6C).