RESUMEN
Using the Elisa-Test of Dakopatts, Hamburg, described by Ishiguro et al and modified by us (Mikrotitration plates instead of tubes, blocking up free bonding capacities in the plates with 1% gel fluid, altered incubation periods) we determined secretory IgA (SIgA) in saliva samples of 376 infants and children. The probands could be divided in three groups: Group 1, serving as controls, consisted of 163 healthy children. Group 2 comprised 111 children suffering from acute infection of the respiratory tract. Group 3 consisted of 102 children with chronic airways diseases, in particular, asthma. In the healthy infants and children we found age dependent increases of SIgA until the age of 4 years. The median values amounted 16.7 (newborns), 59.2 (1st year), 118.2 (2nd year), 149.2 (3rd year), 185.5 (4th year), 159 (5th year) and 175.8 mg/l (5th-13th year). A similar age dependent increase of SIgA was evident in the saliva samples of children suffering from acute infections of the respiratory tract. In the children with chronic airways diseases there was only a slight increase of SIgA during the first 4 years (mean = 78.0-113.5 mg/l) and an abrupt (statistically significant) rise in the fifth year. The median value of SIgA was 216 mg/l in the children aged 5-13 years. Serum IgA along with salivary IgA were measured in 128 children (r = 0.40, p less than 0.001). 6 children had a complete IgA deficiency and 4 children an incomplete IgA deficiency, i.e. low secretory IgA levels in saliva (36.8-50.0 mg/l) and lacking IgA in serum (less than 14 mg/dl).(ABSTRACT TRUNCATED AT 250 WORDS)