Haemolytic activity of Helicobacter pylori against human and animal erythrocytes

Clinical isolates and reference strains of H. pylori (n = 28) were investigated for lytic activity against red blood cells (RBC) of man, sheep, horse, rabbit, hamster and guinea pig. The test medium (HTA) consisted of agar base supplemented with newborn calf serum and washed RBC. In contrast to previous reports, haemolysis of human RBC was detected. Blood group A RBC supported the haemolytic growth of all strains studied. On HTA with blood group 0 RBC, one strain failed to grow and five strains grew nonhaemolytically. The diversity of growth and haemolysis on HTA containing the human and several animal RBC species allowed a differentiation of the strains into eight groups. Using a liquid RBC assay for quantitative measurement of haemolysis, extracts of broth-grown cells of strain ATCC 43504 showed an average haemolysis rate of 75% against sheep RBC and of 83% against human A RBC. Cell-free culture supernatants, however, showed an average haemolysis rate of 57% against sheep RBC and no activity against human A RBC. The data indicate that H. pylori expresses an intracellular haemolytic factor and a cell surface-associated or secreted haemolytic factor which have different RBC specificities. The demonstration of the sensitivity of human RBC supports the hypothesis that the haemolytic property of H. pylori is involved in the pathogenesis of human infection.