Cole agglutinins are directed against which antigen?

Cole agglutinins are specific antibodies that react against the I antigen, which is present on the red blood cells of individuals. These antibodies are typically found in certain types of autoimmune hemolytic anemia, particularly in children with certain infections, such as Mycoplasma pneumoniae. In the context of blood typing and transfusions, these antibodies can cause agglutination of red blood cells if not properly accounted for, which can lead to transfusion reactions.

Understanding the relevance of Cole agglutinins is important in clinical settings where accurate blood typing is crucial, particularly in transfusion medicine and in diagnosing related conditions. The presence of these antibodies and their specificity for the I antigen can significantly impact the selection of compatible blood products.

The other options, such as type O, A, and B antigens, refer to the ABO blood group system, which is entirely different from what Cole agglutinins target. The ABO system is based on the presence of A and B antigens on the surface of red blood cells, which determines an individual's blood type. Since Cole agglutinins do not react with these antigens, they are not relevant in this context.