[Synthesis of natural allohemagglutinins of the ABO system in healthy children aged 3 months to 3 years].

The work was carried out to establish the titre and score of haemagglutination of natural anti-A and anti-B antibodies in healthy children during the first three years of life. The material studied included 900 healthy children aged between 3 months and 3 years and 100 adults serving as controls. The method of test tube haemagglutination was used for determining the titre and score of alloagglutinins in relation to standard erythrocytes always obtained from the same donors. In addition, in 72 children and 10 adults the levels of IgG, IgA and IgM were determined quantitatively. A statistical analysis of the results showed that the levels of anti-A and anti-B alloagglutinins were relatively high at the age of 3 months / about 25% of the adult levels / and increased very rapidly in the first years of life reaching about 90% of the adult level at the end of the 3rd year of life. Besides that, it was demonstrated that it is useful in clinical practice to use the titre and score of natural alloagglutinins as indicators of humoral immunity, especially in children in the first years of life. Acceleration was demonstrated in the intensity of haemagglutination of natural antibodies in the last 40 years since their titre in the contemporary infantile population / up to the age of 1 year / is about 50% higher than that found in 1929. These findings suggest that increased immune reactivity of children observed presently may be due to prophylactic vaccinations.