immunology today, October 1981


Relations between Waldeyer's ring and upper respiratory tract infections Recurrent upper respiratory tract infections ( U R T I ) are among the commonest a b n o r m a l conditions seen by pediatricians and otorhinolaryngologists. Because of the supposed improvement in infectious symptomatology after tonsillectomy a n d / o r adenoidectomy, these surgical procedures are still much in use in m a n y countries of the developed world. Yet there are outstanding questions about the immunological role of the adenoids and tonsils, their relationship to the local and general immune system and to recurrent URTI. Adenoids and tonsils are histologically similar except in the surface epithelium, which is squamous in the palatine tonsil and in the adenoids squamous and ciliated columnar j. Both tissues have four l y m p h o i d c o m p a r t m e n t s ( g e r m i n a l centres, m a n t l e zones, extrafollicular areas and reticular epithelium), which form a tissue unit 2. These lymphoid c o m p a r t m e n t s are disposed around the crypt lumen, which is an i m p o r t a n t area of contact between foreign antigens and immunocytes. T h e r e is a much higher proportion of B cells in the adenoids and tonsils than in peripheral blood but a lower proportion of T l y m p h o c y t e s , null cells and phagocytes. The proportion of Ig-secreting p l a s m a cells is also higher. In both adenoids and tonsils, the I g G - p r o d u c i n g immunocytes are the most frequent cell type, followed by cells producing IgA, I g M and IgD. Normally the largest lymphoid c o m p a r t m e n t in both tissues is represented by the extrafollicular area, while the most populated is the reticular epithelium. But in adenoid hypertrophy, and to a greater extent in recurrent tonsillitis, there is an increase in germinal centre activity, while the differentiation to extrafollicular plasma-cell seems to be decreased 2. In addition, mainly in recurrent tonsillitis, it is possible to observe a low n u m b e r of J - c h a i n positive IgA immunocytes, p r o b a b l y owing to a defect in the switchover from l g M and IgG to lgA 3. The relationship between serum lg a n d adenoid and tonsillar pathology is not clear. I)onovan and SoothilP found low levels of circulating IgA in children with recurrent U R T I u n d e r g o i n g tonsillectomy, while others have reported normal or raised serum Ig levels before tonsillectomy with a decrease of all Ig classes ~ or of IgA only (' after the operation. Two fundamental questions must be asked about the relationship between W a l d e y e r ' s ring lymphoid tissue and the recurrence of U R T I . Are there immunological defects within the adenoids a n d / o r tonsil which might be an underlying cause of recurrent U R T I (in which case the surgical procedure would be useful)? or do recurrent U R T I reflect a more general

immunological defect or even have non-immunological causes (in which case adenotonsillectomy would not be useful and might even be dangerous) ? T h e reported defects in the switchover from I g M and IgG to IgA could be interpreted as a local immunological defect which might predispose to the recurrence of U R T I . O n the other hand there is not yet any firm clinical evidence of the beneficial effects of adenotonsillectomy on recurrent U R T I symptomatology that might be expected: reported improvement 7 was observed only in children without an a p p a r e n t immunological defect before the operation. T h e difficulty in making a j u d g e m e n t is increased by the natural history of recurrent U R T I , which tend to decline in frequency and severity as children get older' 0. There is also some evidence that a generalized i m m u n e defect may be involved in the recurrence of U R T I . At an international meeting on clinical immunology in M a y (15th-17th) M. De M a r t i n o and A. Vierucci reported finding different immunological abnormalities, cellular and humoral, specific and nonspecific, in 22 children with more than 13 U R T I episodes in 1 year. We cannot be sure whether such abnormalities are fundamental to the development of the disease or not but it does not seem unlikely that U R T I may have different pathogenetic mechanisms. It is not possible, at the moment, to make any conclusive statements about the influence of W a l d e y e r ' s ring upon current U R T I in children. O n the other h a n d the available data, from different authors, should m a k e us c a u t i o u s a b o u t r e c o m m e n d i n g a d e n o tonsillectomy in children with recurrent U R T I . R. D'AMELIO

Division of lr~ecZbms Diseases 11, Policlinico Umberlo 1°, 001(51 Rome, Ilaly,

References 1 Korsrud, F. R. and Brandtzaeg, P. (t980) Clin. Exp. Immunol. 39, 361 2 Flrandtzaeg, P., Surjan, L. and Berdal, P. (1978) (2gin. Exp. Immnnol. 31,367 3 Korsrud, F. R. and Brandtzaeg, P. (1981) Scan& J. lmmunoL 13, 281 4 Donovan, R. and Soothill, J. F. (1973) Clin. Exp. lrnmunol. 14, 347 5 Gravina, E., Guarnieri, G. and Gravina-Sanvitale, G. (I980) Min. Pediatr. 32, 461 60stergaard, P. A. (1977) Acta Patho[. Microbiol. Stand. (C) 85, 178 7 Roydhouse, N. (1969) Lancet ii, 93l 8 Rynnel-Dagoo, B., Ahlbom, A. and Schiratzki, H. (1978) Ann. Otol. 87,272 9 Donovan, R. (I973) Proc. Roy. Soc. Med. 66, 413 10 Paradise, J. L., Bluestone, C. D. and Bachman, R. Z., el al. (1978) N. Engl. J. Meal. 298,409 e Elseviel/North-HollandBiomedicalPress1981


Relations between Waldeyer's ring and upper respiratory tract infections.

Relations between Waldeyer's ring and upper respiratory tract infections. - PDF Download Free
105KB Sizes 0 Downloads 18 Views