Similarities and differences in lectin cytochemistry of laryngeal and tracheal epithelium and subepithelial seromucous glands in cases of sudden infant death and controls

Background-It has been speculated that non-specific defence mechanisms of the epithelium and subepithelial seromucous glands play a role in the larynx and lungs in cases of sudden infant death. Methods-The larynx and trachea from five children who had died of sudden infant death (SID) syndrome and five control cases of comparable age were compared for the presence of lectin binding sites (12 different lectins tested). Results-The secretory product of mucin producing cells contained carbohydrates including galactose and sialic acids. Binding sites for fucose and N-acetylgalactosamine were only present in some of the specimens and distribution revealed no correlation between cases of SID and controls. Epithelial cells and serous cells of seromucous glands contained binding sites for sialic acid in cases of SID and controls. Moreover, binding sites for mannose were detected in these cells but were only present in SID cases. The difference between the SID and control groups as to the presence/expression of concanavalin A was highly significant. Conclusions-It is suggested that mucus hypersecretion in SID occurs in response to bacterial toxins or viral infection and is not specific. The different binding sites for mannose in cases of SID and controls could indicate differences in the production of antimicrobial peptides. A disturbed expression pattern of antimicrobial peptides in children who later succumb to SID could be responsible for an imbalance of the local microflora with a higher density of microorganisms on the mucosa. Further studies are required to elucidate the pattern of expression of antimicrobial peptides in subsequent SID victims.