Appendix 04. ABH(O) substances

 

A and B antigens were initially identified on RBCs. However, antigens with similar specificities were later identified in secretions such as saliva, seminal fluid, and ovarian cyst fluid. In addition to RBCs, they were also found on the other types of cells (endothelial cells and epithelial cells). It also became clear that the expression of these antigens is not restricted to humans, but also exists in other species of living organisms.