Soluble and membrane-bound interleukin (IL)-15 Rα/IL-15 complexes mediate proliferation of high-avidity central memory CD8+ T cells for adoptive immunotherapy of cancer and infections.

The lack of persistence of infused T cells is a principal limitation of adoptive immunotherapy in man. Interleukin (IL)-15 can sustain memory T cell expansion when presented in complex with IL-15Rα (15Rα/15). We developed a novel in-vitro system for generation of stable 15Rα/15 complexes. Immunologically quantifiable amounts of IL-15 were obtained when both IL-15Rα and IL-15 genes were co-transduced in NIH 3T3 fibroblast-based artificial antigen-presenting cells expressing human leucocyte antigen (HLA) A:0201, ß2 microglobulin, CD80, CD58 and CD54 [A2-artificial antigen presenting cell (AAPC)] and a murine pro-B cell line (Baf-3) (A2-AAPC15Rα/15 and Baf-315Rα/15 ). Transduction of cells with IL-15 alone resulted in only transient expression of IL-15, with minimal amounts of immunologically detectable IL-15. In comparison, cells transduced with IL-15Rα alone (A2-AAPCRα ) demonstrated stable expression of IL-15Rα; however, when loaded with soluble IL-15 (sIL-15), these cells sequestered 15Rα/15 intracellularly and also demonstrated minimal amounts of IL-15. Human T cells stimulated in vitro against a viral antigen (CMVpp65) in the presence of 15Rα/15 generated superior yields of high-avidity CMVpp65 epitope-specific T cells [cytomegalovirus-cytotoxic T lymphocytes (CMV-CTLs)] responding to ≤ 10- 13 M peptide concentrations, and lysing targets cells at lower effector : target ratios (1 : 10 and 1 : 100), where sIL-15, sIL-2 or sIL-7 CMV-CTLs demonstrated minimal or no activity. Both soluble and surface presented 15Rα/15, but not sIL-15, sustained in-vitro expansion of CD62L+ and CCR7+ central memory phenotype CMV-CTLs (TCM ). 15Rα/15 complexes represent a potent adjuvant for augmenting the efficacy of adoptive immunotherapy. Such cell-bound or soluble 15Rα/15 complexes could be developed for use in combination immunotherapy approaches.

Virus-specific T-cell banks for 'off the shelf' adoptive therapy of refractory infections.

Adoptive immunotherapy with transplant donor-derived virus-specific T cells has emerged as a potentially curative approach for the treatment of drug-refractory EBV+lymphomas as well as CMV and adenovirus infections complicating allogeneic hematopoietic cell transplants. Adoptive transfer of HLA partially matched virus-specific T cells from healthy third party donors has also shown promise in the treatment of these conditions, with disease response rates of 50-76% and strikingly low incidences of toxicity or GVHD recorded in initial trials. In this review, we examine the reported experience with transplant donor and third party donor-derived virus-specific T cells, identifying characteristics of the viral pathogen, the T cells administered and the diseased host that contribute to treatment response or failure. We also describe the characteristics of virus-specific T-cell lines in our center's bank and the frequency with which in vitro culture promotes expansion of immunodominant T cells specific for epitopes that are presented by a limited array of prevalent HLA alleles, which facilitates their broad applicability for treatment.

Artificial Antigen Presenting Cells: An Off the Shelf Approach for Generation of Desirable T-Cell Populations for Broad Application of Adoptive Immunotherapy.

Adoptive transfer of antigen specific T-cells can lead to eradication of cancer and viral infections. The broad application of this approach has further been hampered by the limited availability of adequate numbers of T-cells for treatment in a timely manner. This has led to efforts for the development of efficient methods to generate large numbers of T-cells with specificity for tumor or viral antigens that can be harnessed for use in cancer therapy. Recent studies have demonstrated that during encounter with tumor antigen, the signals delivered to T-cells by professional antigen-presenting cells can affect T-cell programming and their subsequent therapeutic efficacy. This has stimulated efforts to develop artificial antigen-presenting cells that allow optimal control over the signals provided to T-cells. In this review, we will discuss the cellular artificial antigen-presenting cell systems and their use in T-cell adoptive immunotherapy for cancer and infections.

T-cell depleted allogeneic hematopoietic cell transplants as a platform for adoptive therapy with leukemia selective or virus-specific T-cells.

Allogeneic hematopoietic cell transplants adequately depleted of T-cells can reduce or prevent acute and chronic GVHD in both HLA-matched and haplotype-disparate hosts, without post-transplant prophylaxis with immunosuppressive drugs. Recent trials indicate that high doses of CD34+ progenitors from G-CSF mobilized peripheral blood leukocytes isolated and T-cell depleted by immunoadsorption to paramagnetic beads, when administered after myeloablative conditioning with TBI and chemotherapy or chemotherapy alone can secure consistent engraftment and abrogate GVHD in patients with acute leukemia without incurring an increased risk of a recurrent leukemia. Early clinical trials also indicate that high doses of in vitro generated leukemia-reactive donor T-cells can be adoptively transferred and can induce remissions of leukemia relapse without GVHD. Similarly, virus-specific T-cells generated from the transplant donor or an HLA partially matched third party, have induced remissions of Rituxan-refractory EBV lymphomas and can clear CMV disease or viremia persisting despite antiviral therapy in a high proportion of cases. Analyses of treatment responses and failures illustrate both the advantages and limitations of donor or banked, third party-derived T-cells, but underscore the potential of adoptive T-cell therapy in the absence of ongoing immunosuppression.

Bone mineral density of the spine and femur in healthy Saudis.

The reference values of bone mineral density (BMD) were determined in healthy Saudis of both sexes and compared with US / northern European and other reference data. BMD was determined by dual-energy X-ray absorptiometry (DXA) at the lumbar spine and femur including subregions: trochanter, Ward's triangle, and neck, in 1,980 randomly selected Saudis (age range 20-79 years; 915 males and 1,065 females) living in the Jeddah area. Age-related changes in BMD were similar to those described in US / northern European and Lebanese reference data. Decreases in BMD of males were evident (% per year): 0.3-0.8 (lumbar spine), 0.2-0.4 (femoral trochanter), 0.2-1.4 (Ward's triangle), and 0.2-0.7 (femoral neck). Also, decreases in BMD of females were observed (% per year): 0.8-0.9 (lumbar spine), 0.7-0.9 (Ward's triangle), and 0.3-0.7 (femoral neck). Using stepwise multiple regressions that included both body weight and height, the former had 2-4 times greater effect on BMD than the latter. Using the mean BMD of the <35-year-old group the T-score values were calculated for Saudis. The prevalence of osteoporosis in Saudis (50-79 years) at the lumbar spine using the manufacturer's vs Saudi reference data was 38.3-47.7% vs 30.5-49.6 (P<0.000), respectively. Similarly, based on BMD of total femur, the prevalence of osteoporosis using the manufacturer's vs Saudi reference data was 6.3-7.8% vs 1.2-4.7% (P<0.000), respectively. Saudis (> or =50 years) in the lowest quartile of body weight exhibited higher prevalence of osteoporosis (25.6% in females and 15.5% in males) as compared to that of the highest quartiles (0.0% in females and 0.8% in males). The present study underscores the importance of using population-specific reference values for BMD measurements to avoid overdiagnosis and/or underdiagnosis of osteoporosis.