Evidence of enhanced iron excretion during systemic phosphorothioate oligodeoxynucleotide treatment.

BACKGROUND: Phosphorothioate oligonucleotides, in general, possess properties that could be utilized in the development of therapeutic heavy metal chelators. METHODS: Iron excretion was measured in 16 patients participating in studies to test the safety of OL(1)p53, a 20-mer phosphorothioate oligonucleotide complementary to p53 mRNA. Patients were given OL(1)p53 at doses of 0.05 to 0.25 mg/kg/h for 10 days by continuous intravenous infusion. Urine was collected during the study and analyzed for iron, copper, cadmium, and zinc. RESULTS: We found that phosphorothioate oligonucleotides have a high affinity for iron as well as several other clinically relevant toxic metals. Analysis of patient urine following administration of OL(1)p53 reveals a 7.5-fold increase in iron excretion at low doses (0.05 mg/kg/h). CONCLUSIONS: Phosphorothioate oligonucleotides may have therapeutic potential as heavy metal chelators. Low doses of phosphorothioate oligonucleotide facilitated the excretion of iron. Renal clearance of iron-phosphorothioate oligonucleotide complexes most likely involves secretion into proximal tubules.

Human herpesvirus 8 (KSHV) contamination of peripheral blood and autograft products from multiple myeloma patients.

Human herpesvirus 8 (HHV-8), also known as Kaposi's sarcoma-associated herpesvirus (KSHV), has recently been identified within the bone marrow dendritic cells of multiple myeloma (MM) patients. This virus contains homologues to human cytokines such as IL-6 that could potentially stimulate myeloma cell growth and contribute to disease pathogenesis. Since mobilization chemotherapy may increase circulating dendritic cell numbers, we searched for HHV-8 in peripheral blood mononuclear cells (PBMCs) before and after mobilization chemotherapy given to MM patients. Furthermore, we determined if autograft purging using the CEPRATE SC device would reduce the percentage of HHV-8 infected stem cell products. Only two of the 39 PBMC samples collected prior to mobilization chemotherapy contained PCR detectable virus, yet nine of 37 PBMCs collected on the first day of leukapheresis had detectable HHV-8 (P = 0.016). HHV-8 was more frequently identified in autograft products before vs after Ceprate SC selection (40% vs 15%, P = 0.016). Although the role HHV-8 plays in myeloma pathogenesis remains unclear, these results imply that mobilization chemotherapy increases the numbers of circulating HHV-8-infected dendritic cells within the peripheral blood. In addition, CD34 selection of autograft products in MM patients may reduce the reintroduction of virally infected cells following high-dose chemotherapy. Bone Marrow Transplantation (2000) 25, 153-160.

IL-2 expansion of T and NK cells from growth factor-mobilized peripheral blood stem cell products: monocyte inhibition.

The expansion of T and natural killer (NK) cells in growth factor-mobilized peripheral blood stem cell (PSC) products with interleukin-2 (IL-2) requires a reduction in monocyte frequency. Monocytes are enriched with stem cells during apheresis and, in this series of growth factor-mobilized PSC products from breast cancer patients, represented 36 +/- 6% of the cells in the product. Immunophenotyping studies revealed that monocytes inhibited the proliferation of NK cells (CD56+ and CD3- CD8+ CD56+ cells) and T cells (CD3+, CD4+, and CD8+ cells) during IL-2 co-culture for 7, 14, or 21 days. A reduction in monocytes resulted in 61-fold expansion of CD3- CD8+ CD56+ cells compared with a 3.7-fold increase of CD3+ cells by day 21. In addition, following IL-2 co-culture, cells from PSC products with a reduced frequency of monocytes had a significantly increased T cell mitogenic response and NK cell activity in PSC products compared with intact products. We suggest that monocytes inhibit the IL-2-dependent proliferation and augmented function of NK and T cells from growth factor-mobilized PSC products.