Presence of dendritic cells, T lymphocytes, macrophages, B lymphocytes and glandular tissue in the human fetal larynx

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Abstract
Objective The laryngeal mucosa starts to be exposed to infectious agents immediately after birth. The course of laryngeal infections in young children differs significantly from that in adults. The first line of defense encountered by an inhaled infectious agent is the mucosa-associated immune system, which includes immunocompetent cells and secretory components. The cellular elements are partially organized in a typical morphological pattern known as mucosa-associated lymphoid tissue (MALT). Differences in the ability of young children and adults to react to a laryngeal infection raise the questions of whether and to what extent immunocompetent cells are already present in the larynx at birth. These questions were investigated in this study. Material and methods Dendritic cells, T lymphocytes, B lymphocytes, macrophages and glands were examined and detected in an (immuno-)histological study of 8 fetal larynges (14th–22nd week of gestation). Results Immunocompetent cells and glands were present mainly in the epi- and subglottic regions and ventricular folds, whereas the glottis was largely spared. The pattern of distribution was scattered and no organized MALT was seen. Conclusion Essential cell populations of a mucosa-associated immune system for the initiation of an immune response may exist in the human larynx at birth.