Focal prostate basal cell layer disruptions and leukocyte infiltration are correlated events: A potential mechanism for basal cell layer disruptions and tumor invasion

To assess the potential correlation between basal cell layer disruptions and leukocyte infiltration, consecutive sections of normal (n = 5) and tumor (n = 50) prostate tissues were double immunostained for cytokeratin 34βE12 (CK 34βE12) plus leukocyte common antigen, Ki-67, or proliferating cell nuclear antigen (PCNA). Of 2047 acini and ducts examined, 201 contained focal basal cell layer disruptions. Of those, 183 (91%) showed leukocyte infiltration, compared to 67 (33.3%) in 201 morphologically comparable structures with an intact basal cell layer (P < 0.01). Basal cell layers adjacent to or surrounded by leukocytes were often attenuated or fragmented, and leukocytes were generally located at or near disruptions. Disrupted basal cell layers showed a markedly reduced proliferation rate, compared to their non-disrupted counterparts. Cells overlying focal basal cell layer disruptions often displayed distinct changes in the size, nuclear shape, density, and polarity, compared to those away from disruptions. A vast majority of proliferating tumor cells were located at or near basal cell layer disruptions. These findings suggest that focal basal cell layer disruptions and leukocyte infiltration are correlated events, representing a potential trigger factor for prostate tumor invasion.