Aliquots of digests were also used in the IL-2 functional assay

described below. Functional IL-2 was measured using CTLL-2 cells (ATCC) as described elsewhere28 with minor modifications. In brief, digested samples were serially diluted 1 : 2, then 50 μl of test supernatant was added to 3·5 × 104 to 5·0 × 104 CTLL-2 cells per well in 100 μl medium in a 96-well plate and incubated at 37° in 5% CO2 for 18–22 hr. At the end of this period, 75 μg/well Thiazolyl Blue Tetrazolium Bromide (MTT) (Sigma-Aldrich) was added and the plate was incubated for 8 hr at 37° in 5% CO2. Cells were lysed with 100 μl/well 10% SDS (Gibco®; Invitrogen) acidified with HCl, incubated at 37° in 5% CO2 overnight, and absorbance 570 nm was read.29 Recombinant human IL-2 standard (Peprotech) was serially diluted with 0·5 ng delivered to CTLL-2 cells in the first well. All animal experiments were performed in accordance with guidelines established by Dabrafenib purchase Deforolimus mw the National Institutes of Health and the University Committee on Animal Resources at the University of Rochester. C57BL/6J mice were purchased from The Jackson Laboratory (Bar Harbor, ME). Human PSA transgenic mice were backcrossed onto the C57BL/6J background

and were used as a source of PSA-expressing prostate tissue.30 Ventral prostates from wild-type C57BL/6J (Jackson) (non-transgenic; NTG) and PSA transgenic C57BL/6J (TG) mice were surgically removed and placed in 600 μl Dulbecco’s modified Eagle’s medium (Gibco®; Tolmetin Invitrogen) supplemented with 0·005 mg/ml bovine insulin (Sigma-Aldrich), 10 nmtrans-dehydroandrosterone (Sigma-Aldrich), 5% fetal calf serum (Hyclone, Logan, UT), 5% Nu-serum IV (BD Biosciences), and 0·05% penicillin/streptomycin (Sigma-Aldrich). Fusion protein was added to explant culture and incubated at 37° in 5% CO2 and 100 μl aliquots were removed at 1, 12, 24 and 48 hr and stored at −20° until use. Prostate extracts were made using ventral prostates homogenized in a Dounce homogenizer in 100 μl of 50 mm Tris–HCl, 100 mm NaCl pH 7·8. Extracts were centrifuged to remove debris and the supernatants were stored at −20°. Total protein concentration

was determined using the Bio Rad Protein Assay (Bio Rad) according to the manufacturer’s recommendation and equal amounts of protein extracts were used for fusion protein digestions described earlier. The PSA levels in culture supernatants or in the prostate extracts were measured using a capture ELISA as described previously31 with minor modifications. Human IL-2 was detected by standard Western blot technique using a rabbit anti-human IL-2 antibody (Leinco, St Louis, MO; 1·0 μg/ml) in TBS-M-Tw followed by a goat anti-rabbit HRP-conjugated antibody (Leinco; 0·2 μg/ml) in TBS-M-Tw. The blot was developed using the Amersham ECL Plus Western blotting detection system (GE Healthcare) according to the manufacturer’s recommendations.