[Blood groups and disease]

The erythrocyte membrane was used as general model for the plasma membrane knowledge. Some of their structures are antigens from blood group systems being characterized at molecular and functional level as specific receptors, transporters or enzymes, even receptors for infectious agents. Plasmodium vivax malarial parasites require the Duffy blood group glycoprotein to penetrate into human red blood cells and the main antigen of P system (P1) is also the Parvovirus B19 receptor. Furthermore, these substances have an effect on several tissues, plasma and secretions involving pathogenic relationships. Certain aggressive Escherichia coli strains require the P1 antigen to attach to the urothelial cells, the Lewis(b) antigen is the gastric receptor for H. pylori, the anti-B from O or A individuals might protect them against the sepsis produced by E. coli, the Lewis group determines the CA-19.9 serum levels or the protective effect of breast milk. However, the most important effect could be the plasma hypocoagulability observed among the O blood group population (with lower factor VIII levels) in association with a reduced prevalence of thromboembolic diseases.