The role of blood group antigens in infectious diseases

The medical literature contains a large number of publications attempting to correlate blood groups with disease. Many of these reports are poorly documented and have limited scientific validity. Only a few agents, such as malaria parasites and parvovirus B19, infect red blood cells (RBCs) and precursors. Most other agents use RBCs as carriers to the target tissue. There is an excess of blood group A individuals among cancer patients compared with normal individuals; malignancy has also been associated with the Lewis antigen. Plasmodium vivax only enters RBCs when the Fy6 Duffy protein is present. Certain Escherichia coli organisms will only attach to epithelial cells carrying P or Dr blood group antigens. The P antigen Is also the receptor for parvovirus B19. Le(b) appears to be the receptor for Helicobacter pylori in gastric tissue. The high frequency blood group antigen AnWJ is the receptor for Haemophilus influenzae. Knowledge of the functions of RBC surface molecules Is expanding and the ability to generate experimental animals devoid of certain molecules will clarify their physiological role.