Dendritic and lymphocytic cell infiltration in prostate carcinoma

Abstract

We examined the distribution of CD1a+ cells and CD8+ and CD4+ T lymphocytes in prostate cancer (PCa) and correlated these with clinicopathological parameters. We also investigated whether the distribution of these cells was related to the expression of the cell membrane protein B7-H3, a putative negative regulator of the immune response expressed on PCa cells. A cohort of 151 PCa patients treated with radical prostatectomy (RP) was followed prospectively from 1985 until 2006 with a median follow-up of 9 years. Whole-mount sections of PCa specimens were immunostained to identify immune cells. A low number of CD1a+ cells was significantly associated with a high Gleason score and high pathological stage of pT3. The number of CD1a+ cells correlated significantly with the number of intratumoral and stromal CD8+ and stromal CD4+ lymphocytes. Kaplan-Meier analysis showed a tendency toward impaired biochemical progression-free survival in patients with few CD1a+ cells within their RP specimens. The expression of B7-H3 correlated inversely with the number of CD1a+ cells and intratumoral CD4+ lymphocytes; there was a trend for a similar inverse relationship between B7-H3 expression and the number of CD8+ lymphocytes. Our findings suggest that high-grade prostate carcinoma cells manipulate the immune system and that these changes contribute to the mechanism underlying tumor escape from immune surveillance.