The secretory immunoglobulin system in urothelial neoplasia.

The role of the secretory immunoglobulin system in urinary tract neoplasia has been investigated by staining formalin-fixed, paraffin-wax embedded sections of normal and abnormal urinary tract epithelium for secretory component (SC), IgA and J (joining) chain. Normal mucosa contains IgA with J chain and SC as a thin superficial layer on surface umbrella cells and in small amounts in the cytoplasm of intermediate cells. Inflamed mucosa is infiltrated by many IgA and J chain positive plasma cells in the lamina propria and there is IgA, SC and J chain in the cytoplasm of the second layer of the epithelium as much as in surface umbrella cells. Epithelium with moderate to severe dysplasia and invasive transitional cell carcinoma is almost always negative, containing only occasional cells with cytoplasmic IgA, J chain and SC, whilst surface staining is entirely absent.