Detection of immune complexes in the sera of human newborns suspected of neonatal infection.

The special characteristics and relative immaturity of the immune system in human neonates favour the constitution and persistence of circulating immune complexes after any antigenic invasion so that their detection in serum during the first week of life could be of paticular interest for the early diagnosis of a neonatal infection. In this study, using a technique based on the inhibition of a latex agglutination, we detected circulating immune complexes in sixty-four neonates suspected of infection, at a significantly higher titre than in eleven newborns considered to be completely devoid of any clinical abnormalities. The level of those circulating immune complexes was related to the severity of a clinically considered as a high risk of infection. On the other hand, no significant correlation was found between the infection score and the level of fibrinogen in the blood or the percentage of nonsegmented neutrophils. Moreover, no correlation was demonstrated between each of these two classical biological tests and the level of circulating immune complexes.