IgA transport mechanism through the human nasal mucosa: an immunoenzymatic ultrastrutural study.
The role of secretory IgA antibodies in the antiviral and antibacterial defense of the higher respiratory tract has been widely demonstrated, and the IgA determination in the nasal secretion has become of the highest value in the clinical study. The mechanism by which IgA reaches nasal secretion through the mucosa is still a matter of discussion and neither hypothesis put forward by Tomasi (i.e. free filtration through the epithelic-connectival interstitium or transcellular transport plus active secretion) has so far been fully demonstrated. By using a horseradish peroxidase labeled IgG directed against human IgA we have performed, with suitable controls, a semi-quantitative study on semi-thin and thin section of the IgA behaviour at the level of human nasal mucosa. We have shown that IgA, made up and secreted in the connectival interstitium by specific plasma cells, would be taken up by endocytosis by epithelial cells, where it can be seen especially in the Golgi apparatus and in the large secretion granules. Since in the intracellular transport of pinocytic vesicles actin microfilaments and microtubules undoubtedly play a major role, with ATP utilisation, further studies using either physical factors (e.g. exposure to cold) effecting ATP utilisation or chemical ones (e.g. cytochalasin B and colchicine) depolymering respectively microfilaments and microtubules, should be performed in order to bring further proofs in favor of the active transport IgA mechanism suggested by our present investigations.
D000255:Adenosine Triphosphate / Q000502:physiology; D001693:Biological Transport, Active; D003080:Cold Temperature; D004848:Epithelium / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D006735:Horseradish Peroxidase; D006801:Humans; D007124:Immunoenzyme Techniques; D007070:Immunoglobulin A / Q000378:metabolism*; D007071:Immunoglobulin A, Secretory / Q000378:metabolism*; D008854:Microscopy, Electron; D009297:Nasal Mucosa / Q000378:metabolism* / Q000648:ultrastructure; D010873:Pinocytosis; D012270:Ribosomes / Q000378:metabolism
D007070:Immunoglobulin A; D007071:Immunoglobulin A, Secretory; D000255:Adenosine Triphosphate; D006735:Horseradish Peroxidase