Phenotypic characterization of the infiltrating immune cells in normal prostate, benign nodular prostatic hyperplasia and prostatic adenocarcinoma.

BACKGROUND

Immune cell infiltrate is a constant feature in normal prostate, benign nodular prostatic hyperplasia and prostatic adenocarcinoma. This study elaborates on the cells of the immune system present in normal prostate, benign nodular prostatic hyperplasia and prostatic adenocarcinoma.

HYPOTHESIS

Here, we hypothesized that "the development of benign nodular prostatic hyperplasia and prostatic adenocarcinoma is associated with numeric alterations of the immune cell infiltrate".

MATERIALS AND METHODS

A total of 50 transurethral prostatic resection specimens, each entailing normal prostate, benign nodular prostatic hyperplasia and high grade prostatic adenocarcinoma were evaluated for the density and phenotype of the immune cells using immunohistological methods and mouse monoclonal antibodies decorating T cells (CD3), histiocytes (CD68) and B lymphocytes (CD20).

RESULTS

Immune cell infiltrate was composed of T cells, histiocytes and B-lymphocytes. CD(+)3 T lymphocytes and CD68(+) cells were the predominant cell populations. We observed variations in the density of the immune cells among the normal prostate, benign nodular prostatic hyperplasia and high grade prostatic adenocarcinoma. Compared with normal prostate, benign nodular prostatic hyperplasia had a statistically significant high density of immune cells (3.4+/-0.4versus 13.5+/-1.0, P<0.00). In contrast, a significant decrease in the counts of these cells was observed in high-grade prostatic adenocarcinoma compared to benign nodular prostatic hyperplasia (13.5+/-1.0 versus 5.2+/-0.3, P<0.01).

CONCLUSIONS

The increased density of immune cells (predominantly CD(+)3 T cells) in benign nodular prostatic hyperplasia suggests that the initial response to cellular damage is mediated by cell-mediated immunity. The decreased density of immune cells in high-grade prostatic adenocarcinoma may reflect immunosuppression. The underlying mechanisms of these numeric variations are open for further investigations.