Innate immune lectins kill bacteria expressing blood group antigen

Innate immune lectins kill bacteria expressing blood group antigen
A century ago Landsteiner demonstrated that blood group antigen ABO(H)
expression differs between individuals. The expression of ABO(H) causes deletion of
cells that generate self anti-blood group antibodies, which permits transfer of blood
products between immunologically compatible individuals. However, this cellular
deletion results in a gap in the adaptive immune response toward pathogens bearing
cognate blood group antigens. The mechanism of overcoming these gaps in adaptive
immunity is unknown. Here we report that two innate immune galectins specifically
recognize and kill human blood group B antigen-expressing E. coli, while failing to
alter viability of other E. coli strains or other gram-negative or gram-positive
organisms. Killing by both galectin-4 and galectin-8 resides entirely within their Cterminal domains and occurs independent of complement, providing specific innate
immunity against blood group B positive pathogens regardless of an individual’s
blood group status. These results demonstrate that specific innate defense lectins
exist that can provide immunity against pathogens that display blood group selfantigens on their surface.