Opsonic requirements of Helicobacter pylori

The opsonic requirements of Helicobacter pylori were investigated in a series of experiments with human polymorphonuclear leucocytes (PMNL). Pre-incubation of H. pylori with pooled normal human serum (NHS) in concentrations of 5–20% significantly increased the uptake of radiolabelled bacteria by PMNL. Treatment of the bacteria with NHS 30% caused the release of radiolabel and this effect was abolished by heating serum to 56°C, suggesting that H. pylori is serum-sensitive and that complement is involved. Opsonisation of H. pylori with NHS concentrations of 10–30% significantly increased PMNL chemi-luminescence. Removal of specific antibody had no effect. Removal of either the classical or alternative complement pathways produced no significant change in PMNL chemilum-inescence, indicating that either pathway is sufficient for opsonisation on its own. The results confirm that complement is the most efficient opsonin for H. pylori.