AUTOAGGLUTINATION is defined as the agglutination of a person's red cells by his own serum, because of the presence of an absorbable agglutinin in the serum and a corresponding agglutinogen in the cells (Wiener1).
Although reports concerning clumping or sticking together of red cells, observed when counting red cells, go back as far as 1890 (Reitman,2 Klein,3 Ascoli4 and others), it is not certain whether these authors dealt with true autoagglutination or with pseudoagglutination (rouleaux formation). The first comprehensive description of true autoagglutination was given by Landsteiner5 (1903). He described the cold (auto) agglutinin as present in many normal serums, active at a temperature of 0 to 5 C. only and effective not only against the cells of the same person but also against each group of human erythrocytes and some groups of animal erythrocytes. The agglutination is reversible by warming and reappears in the