When the antigens on erythrocytes bind with antibodies in plasma?

When the antigens on erythrocytes bind with antibodies in plasma, it leads to agglutination, which is the clumping together of red blood cells. This process is also known as hemagglutination. Agglutination occurs when the antibodies bind to specific antigens on the surface of the red blood cells, causing them to cross-link and form clumps. This can lead to various health conditions, such as anemia and transfusion reactions, if the agglutination is severe or incompatible.