Lymphocyte response to transitional cell carcinoma: peripheral cytotoxicity and local tumor infiltration

Relación entre la exposición a pesticidas y el desarrollo de carcinoma urotelial vesical superficial de bajo grado

BACKGROUND AND OBJECTIVE

Few studies have been published analyzing the association between pesticides use and the increased risk of developing urothelial cancer of the bladder (UCB). The aim of this work was to investigate, in a geographical area with a high prevalence of UCB (Axarquia, Malaga province, southern Spain) if a) subjects with occupational exposure to pesticides have greater risk of developing UCB and b) there are histopathological differences with regard to UCB in patients without any exposure.

PATIENTS AND METHOD

Case control study. During two years (1994-1996) 96 cases of UCB were included. The histologic grade and the depth of the invasion as well as the associated inflammatory infiltrate were analyzed. A questionnaire was answered by the patients.

RESULTS

58.3% of the case group were working with or had history of exposure to pesticides, compared to 40.6% in the control group (OR = 2.04; 95% CI, 1.1-3.6). The risk increased with a greater time of exposure. In exposed subjects, low grade tumors (OR = 2.6; 95% CI, 1.3-5.2) as well as superficial tumors (OR = 2.3; 95% CI, 1.2-4.4) were more frequent. They were more frequently accompanied by a chronic inflammatory infiltrate (OR = 4.5; 95% CI, 1.8-11.1).

CONCLUSIONS

The subjects with occupational exposure to pesticide have greater risk of developing UCB, which is directly proportional to the exposure time. In comparison with the population in the zone without exposure, patients who use pesticides present low grade UCB and less invasive tumors more frequently. These facts were not modified when they were adjusted for tobacco consumption. Exposed patients have UCB with chronic (moderate) inflammatory reaction more frequently than the tumors in non-exposed subjects.

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.

Immunoresponse of tissue infiltrating lymphocytes in bladder tumors

Local immunocompetence was evaluated immunohistochemically in patients with bladder tumors before and after local injections of an immunomodulator. The subpopulations of tissue infiltrating lymphocytes (TIL) were examined by staining six serial sections with Leu4, Leu7, Leu10, LeuM3, OKT4, and OKT8 antibodies. T cells predominated over B cells in 19 of 25 bladder tumors. T cell infiltration was prominent around tumor cells, and it was marked in non-invasive tumors. B cells were rare in the stroma. In patients with low-stage tumors, OKT8 cells were more prominent than OKT4 cells. NK cells accumulated within cancer nests but their infiltration was scanty in invasive bladder tumors. Before surgery, immunomodulators (OK-432, IL-2) were injected intratumorally. Their administration resulted in marked increase of T and NK cells, irrespective of the stage of disease; there was a slight increase in B cells. These findings suggest that local immunosurveillance plays a role against bladder tumors. Further studies are required to elucidate host immune responses in the microenvironment of the cancer site, as well as the systemic immune reaction.