Secretory TgA, free secretory component and IgD in saliva of newborn infants

Aim. To determine levels of secretory IgA (sIgA), free secretory component (FSC) and IgD in saliva of newborn infants at the age of 1 day and to evalu ate the detection patterns, the influence of saliva flow and the relation t o serum derived proteins. Methods. Seventy-three healthy newborn infants were studied. Saliva was obt ained from the bottom of the mouth and buccal sulci using a sterile polyeth ylene tube connected to a syringe. SIgA, FSC, IgD and albumin were measured by radial immunodiffusion. Results. SIgA was detected in 74.0% of all saliva samples, whereas detectio n rates for FSC and IgD were 94.5% and 75.3%, respectively, Investigation o f detection patterns and their relation to saliva flow indicated that secre tion of sIgA and FSC into the oral cavity is under similar regulation. Leve ls of IgD were found to be independent from saliva flow, as well as from co ncentrations of serum-derived proteins suggesting different regulative mech anisms compared to sIgA and FSC. The flow rate of unstimulated whole saliva in newborn infants was found to be 15 times lower compared to adolescents, emphasizing the role of saliva flow as a limiting factor for secretion of sIgA and FSC. Conclusion. SIgA, FSC and IgD can be determined in saliva of newborn infant s even in the first day of life. The saliva flow rate has to be considered when evaluating the function and biological relevance of the oral mucosal i mmune system of newborn infants shortly after birth. (C) 2001 Elsevier Scie nce Ireland Ltd. All rights reserved.