Secretory immunoglobulin A (SIgA) anti-casein and SIgA anti-β-lactoglobulin (BLG) were determined in the saliva of 158 healthy mature infants at birth and in breast milk samples using a direct Elisa technique. IgG anti-casein and anti-BLG were measured in serum samples from mothers and newborns (cord blood). A high risk of allergy was defined in 66 infants who had cord blood (CB)-IgE levels ≥0.9 IU/ml and/or parents with atopic diseases. Thirty infants had CB levels <0.9 IU/ml and parents without clinical symptoms of atopy but with elevated serum IgE concentrations or type I skin reactions to common allergens (low risk). Sixty-two infants had CB-IgE levels <0.9 IU/ml and healthy parents (no risk). The groups were matched for social status, smoking and dietary habits. SIgA anti-casein and anti-BLG were detected in all newborns. SIgA anti-casein was significantly higher (p <0.05) in high risk infants (median 157; 50% confidence limits 45–270) than in no risk (48; 25–150) or low risk infants (43; 21–130). SIgA anti-casein values correlated with maternal allergy, maternal allergy plus CB-IgE, but not with paternal allergy. Breast milk SIgA anti-BLG was depressed (p <0.05) in mothers with manifest allergy compared to healthy mothers. Determination of salivary SIgA anti-casein may represent an additional screening method for early detection of infants with atopic disposition.

One hundred and fifty-eight healthy mature newborns were divided into 3 groups according to their risk of allergy: Group A, no risk (n = 62), group B, low risk (n = 30) and Group C, high risk (n = 66). Saliva was collected at birth and after 3 and 6 months. SIgA anti-casein and anti-beta-lactoglobulin were determined by a direct ELISA technique. The highest concentrations of secretory antibodies were measured after birth. After 3 months, breast fed infants had lower salivary SIgA anti-casein concentrations than the group receiving cow's milk (p less than 0.01). The effect of breast-feeding was seen even after a nursing period of only 3 weeks. Infants without risk of allergy fed cow's milk exclusively had higher SIgA anti-casein (p less than 0.03) and anti-beta-lactoglobulin concentrations than low risk infants at the age of 6 months. These data show a modifying effect of breast feeding on salivary SIgA production against cow's milk protein.

Normal newborns regularly form circulating antibodies to milk proteins by LOto 14 days of life. Concentrations of these antibodies are influenced by gestational age but not by passive maternal antibody. Secretory antibodies of the 19A and 19M-isotype directed against casein and (3-lactoglobulin are present in the saliva of normal neonates. SlgA-anti-casein is higher in saliva of newborns at risk to develop atopic disease. (Allergy Proc 12, 5: 309-312, 1991.)

Elevation of salivary SIgA-anti-casein has been shown to occur in newborn infants at risk of allergy. The present study was designed to follow 158 infants over 3 years to relate the onset of clinical disease to SIgA levels at birth. Newborn infants were divided into 3 groups according to their risk of allergy: Group I, (n = 62; no allergy risk); Group 11, (n = 30; low allergy risk); Group 111 ( n = 66; high risk group). The groups were matched for smoking, social background, sex, and dietary habits of the patients. SIgA-anti-casein was determined by a direct ELISA. During the first year 59 infants developed atopic diseases (n = 37 of Groups I and 11; II = 22 of Group 111). After 3 years 37/61 infants of the high risk group had developed allergic symptoms. The frequency of atopic disease correlated with increased salivary antibody titers at birth (p < 0.05). 54% of infants with antibody titers > 250 EU/ml developed