Cytokine expression pattern in benign prostatic hyperplasia infiltrating T cells and impact of lymphocytic infiltration on cytokine mRNA profile in prostatic tissue

The aim of the study is to characterize the type of immune response in benign prostatic hyperplasia (BPH) tissue. BPH tissue-derived T cells (n = 10) were isolated, activated (PMA + ionomycin), and analyzed for intracellular reactivity with anti-IFN-γ and IL-2, -4, -5, -6, -10, and -13, as well as TNF-α and -β by four-color flow cytometry. Lymphokine release was tested using Th1/Th2 cytokine bead arrays. The amount of IFN-γ and IL-2, -4, -13, and TGF-β mRNA expressed in normal prostate (n = 5) was compared with that in BPH tissue separated into segments with normal histology (n = 5), BPH histology with (n = 10) and without (n = 10) lymphocytic infiltration, and BPH nodules (n = 10). Expression of lymphokine receptors was analyzed by immunohistology, flow cytometry, and RT-PCR. We found that 28 ± 18% of BPH T helper cells were IFN-γ⁺/IL-4^- Th1 cells, 10 ± 2% were IFN-γ^-/IL-4⁺ Th2, and 12 ± 6% were IFN-γ+/IL-4⁺ Th0 cells. In relation, cytotoxic and double-negative BPH T lymphocytes showed a slight decrease in Th1 and Th0 in favor of Th2. In double-positive BPH T lymphocytes, the trend toward Th2 (35 ± 15%) was significant (Th1: 12 ± 7%; Th0: 5 ± 4%). Lymphokine release upon stimulation was found in the case of IL-2, IL-5, IFN-γ, and TNF-α > 4 μg; of IL-4 > 2 μg; and of IL-10 > 1 μg/ml. Expression of lymphokine mRNA in tissue was increased (2- to 10-fold) in infiltrated BPH specimens with and without BPH histology. The infiltrated BPH specimens with normal histology differed from those with BPH histology, most evident by the significant decrease in IFN-γ and the increase in TGF-β mRNA expression. Infiltrated BPH specimens with BPH histology expressed significantly more IFN-γ (5-fold), IL-2 (10-fold), and IL-13 (2.8-fold) when compared with noninfiltrated BPH specimens. BPH nodules, however, showed the highest level of expression of IL-4 and IL-13, with only intermediate levels of IFN-γ and very low levels of IL-2 mRNA. Immune response in histologically less transformed BPH specimens is primarily of type 1, whereas in chronically infiltrated nodular BPH and especially within BPH nodules, it is predominantly of type 0 or type 2.