Dear Editor,

The study of Groenland et al contributes remarkably to the understanding of the role of intenstinal colonisation and the maturation of the mucosal immune system.

However, with reference to reports of MacDonald,[1] Savilahti,[2] and Burgio et al,[3] they suggest that the mucosal immune system with its predominant secretory IgA is quantitatively and functionally defective for a variable period after birth.

Within the last 10 years growing evidence could be found that the mucosal immune system is well established and we have recently shown that high levels of secretory IgA can be found in saliva of newborn infants shorty after birth.[4] Additionally we could not analyse any significant differences in secretory IgA levels comparing preterm and term infants in their first 9 months of life.[5]

We therefore believe that the mucosal immune in infancy is well developed as early as in the first days after birth and should be considered when evaluating the protective potential as well as the potential for developing allergic diseases.

BM Seidel
S Schubert
Children's Hospital, University of Leipzig
Division of Paediatric Immunology
Oststrasse 21-25
04317 Leipzig, Germany

References
(1) MacDonald TT. Development of mucosal immune function in man: potential for GI disease states. Acta Paediatr Jpn 1994;36:532-6.

(2) Savilahti E. Immunoglobulin-containing cells in thew intestinal mucosa and immunoglobilins in the intestinal juice in children. Clin Exp Immunol 1972;11:415-25.

(3) Burgio GR, Lanzavecchia A, Plebani A, Jayakar S, Ugazio AG. Ontogeny of secretory immunity: levels of secretory IgA and natural antibodies in saliva. Pediatr Res 1980;14:1111-14.

(4) Seidel BM, Schulze B, Kiess W, Vogtmann C, Borte M. Determination of secretory IgA and albumin in saliva of newborn infants. Biol Neonate 2000;78:186-90.

(5) Seidel BM, Schulze B, Schubert S, Borte M. Oral mucosal immunocompetence in preterm infants in the first 9 months. Eur J Pediatr 2000;159:789.