LARYNX-ASSOCIATED LYMPHOID-TISSUE (LALT) IN YOUNG-CHILDREN

Background: Mucosa-associated lymphoid tissue (MALT) plays a central r ole in mucosal immunity, Whereas the characteristics and function of M ALT in the intestine are well established, almost nothing is known abo ut MALT in the larynx. Methods: In this study we examined the morpholo gy and the lymphocyte subset composition of MALT in the larynges of ch ildren who had died of sudden infant death or various defined traumati c or nontraumatic causes. Results: Organized lymphoid tissue was found in the supraglottic parts of the larynx in nearly 80% of the children in both groups, This lymphoid tissue showed all morphological signs o f MALT, such as typical lymphoid follicles with germinal centers, infi ltration of the overlying epithelium by lymphocytes, and high endothel ial venules (HEV), Thus we will use the term LALT (larynx-associated l ymphoid tissue) to refer to this tissue, The lymphoid follicles of LAL T contained mainly B lymphocytes with some CD4(+) lymphocytes in the g erminal centers. Remarkably, T lymphocytes of both subset types and B lymphocytes were observed in comparable numbers in the parafollicular area, Conclusions: We assume that LALT is a physiological structure of the larynx in young children, The morphology and the distribution of lymphocyte subsets are similar to those of MALT in the human gut. LALT may be a regular part of the mucosal immune system in young children with the role of respiratory inductive site for mucosal immunity. (C) 1997 Wiley-Liss, Inc.