Secretory IgA (S IgA) is the predominant immunoglobulin in external secretionsand has distinctive antigenic and structural differences from serum IgA. Also, it is the assembledmolecule which consists of SC and IgA dimer. As regards the transport mechanism of this S IgA, in salivary glands, there have been only a few reports.
Therefore, the rabbit anti-human SC antibody was purified by the immunoadsorbent, and byuse of this, the present study was undertaken to clear the sites of synthesis of SC and the transportpathway of S IgA in human salivary glands by the immunofluorescent antibody technique.
The following results were obtained.
1) In salivary glands SC was synthesized in serous epithelial cells (serous acinar cells, smallduct cells), but was not in mucous epithelial cells (mucous acinar cells).
2) It seemed that the quantity of synthesized SC was larger in small duct cells than in serousacinar cells.
3) Since cytoplasms and margins of serous cells were entirely stained by anti-SC and anti-IgA, it appeared that SC and IgA were present in cytoplasms and cell membranes of serous cells as inintestinal crypts.
4) Results obtained by the double staining of salivary glands were not distinct so well as thatof intestinal crypts. But the whole of cytoplasms and margins of serous cells showed yellowfluorescence mixed with anti-SC and anti-IgA.
5) According to this mixed fluorescence that meant S IgA and the fact that IgA existed in cytoplasmsand margins of serous cells, it was suggested that IgA associated with SC in cell membranesor cytoplams of serous cells, and that subsequently S IgA was secreted into lumens via cellmembranes or cytoplasms. And it seemed that mucous cells did not take part in the secretionof S IgA.
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