Immunohistochemical detection of tissue-infiltrating lymphocytes in mild urothelial dysplasia.

The presence and distribution of immunocompetent cells in normal and dysplastic urothelium of the bladder were investigated in 3 patients. Using an indirect immunoperoxidase staining procedure, monoclonal antibodies reacting with B (Leu12+) and T (Leu4+) cells, cells of the suppressor/cytotoxic (Leu2a+), helper/inducer (Leu3a+) and natural killer (Leu7+) phenotypes, monocyte-macrophages (LeuM3+), and cells expressing interleukin-2 receptor and HLA-DR antigen (HLA-DR+) were tested in all specimens. The results confirmed the presence of a well ordered and compartmentalised distribution of immunocompetent cells in the normal mucosa far from dysplasia. There was an increased number of lymphocytes in the hyperplastic/dysplastic urothelium with associated Von Brunn's nests. Leu2a+ cells, HLA-DR expressing cells and monocyte-macrophages were present inside the epithelium, particularly within dysplasia and von Brunn's nests, but the Leu3a+/Leu2a+ ratio was not inverted (0.48 + 0.1 to 0.74 + 0.2). These findings reveal that in mild urothelial dysplasia with von Brunn's nests there is a spatial modification of the immunological barrier associated with the mucosa.