Isoagglutinin

noun

1. An isoantibody normally present in the serum of an individual that causes the agglutination of the red blood cells of another individual of the same species.
2. An agglutinin directed against cells of animals of the same species, as the one furnishing the agglutinin.
3. an antibody produced by one individual that causes agglutination of red blood cells in other individuals of the same species