IL-15 but not IL-2 rapidly induces lethal xenogeneic graft-versus-host disease

Abstract

IntroductionXenogeneic graft-versus-host disease (X-GVHD) is the only experimental model of human allogeneic GVHD that incorporates human T cells and recapitulates the T-cell expansion and tissue destruction seen in patients. Severe combined immunodeficient (SCID) mice reconstituted with human peripheral-blood lymphocytes (hu-PBL-SCID) demonstrate, albeit infrequently, lethal X-GVHD associated with high levels of human T-cell engraftment and inflammation of the liver, kidneys, spleen, and lung. 1 We have previously demonstrated that administration of continuous, lowdose recombinant human IL-2 (rhIL-2) to hu-PBL-SCID mice does not increase X-GVHD mortality. 2 IL-15 is structurally similar to IL-2 and uses identical ␤ and ␥ receptor subunits for signaling, but is produced by antigen-presenting cells and demonstrates in vivo activities distinct from IL-2. Recently, data from our laboratory and others have shown that endogenous or exogenous administration of IL-15 increases mortality in murine models of acute allogeneic GVHD. 3,4 Therefore, we have hypothesized that exogenous rhIL-15 would enhance X-GVHD mortality in hu-PBL-SCID mice in contrast to the effects of rhIL-2. Study design Hu-PBL-SCID mouse modelHuman PBLs (5 ϫ 10 7 ) were obtained from healthy donors under an institutional review board (IRB)-approved protocol and injected (intraperitoneal) into 8-to 12-week-old female CB17 SCID mice (Taconic Farms, Germantown, NY) pretreated with murine IL-2R␤ antibodies. 2,5 This regimen eliminates host natural killer cells 6 and increases human T-cell chimerism. 7 Mice were killed as described. 3 All animal research was approved by The Ohio State University. Approval for the use of human subjects was obtained from The Ohio State University IRB. Informed consent was provided according to the Declaration of Helsinki. CytokinesAnimals were dosed with 10 g/d rhIL-15 (Amgen, Thousand Oaks, CA), rhIL-2 (Proleukin; Chiron, Emeryville, CA), or phosphate-buffered saline (PBS) containing 0.05% human albumin via subcutaneous Alzet miniosmotic pumps (Model 1007D; DURECT, Cupertino, CA) beginning 1 day after injection of human PBLs. In vivo antibody treatmentAnimals were treated with anti-human CD3 (50 g/mouse, Orthoclone-OKT3; Ortho Biotech Products, Raritan, NJ) or control mouse immunoglobulin G (IgG; Sigma, St Louis, MO) via intraperitoneal injection on days 1 to 5 after injection of human PBLs. 8 HistopathologyBlinded histologic samples were prepared as described, 3 reviewed by a board-certified veterinary pathologist (D.K.), and scored for lymphocytic infiltration and tissue damage characteristic of X-GVHD. 9 Cytokine bead arrayThe Human Th1/Th2 Cytokine Bead Array (BD Pharmingen, San Diego, CA) was used to measure IL-4, IL-5, IL-10, interferon-␥ (IFN-␥), and tumor necrosis factor-␣ (TNF-␣) in plasma samples as described. 3 StatisticsMedian survival times were compared using the log-rank test. Student t test and the exact Wilcoxon rank sum test were used for the remaining comparisons. Results and discussionAdministration of r...

Factors affecting human T cell engraftment, trafficking, and associated xenogeneic graft-vs-host disease in NOD/SCID β2mnull mice

“…Although we did not evaluate the development of X-GVHD in the absence of pre-transplant irradiation, others have reported no [31] or little [30] lethal X-GVHD following injection of huT into unconditioned NOD/SCID-β2m null mice. In contrast, lethal X-GVHD is observed following administration of huT and human IL-15 to nonirradiated SCID recipients pre-treated with a monoclonal antibody to murine CD122 (to deplete residual host NK cells) [38]. In this study, we found that 20 of 34 (59%) NOD/SCIDβ2m null recipients developed lethal X-GVHD following pre-transplant conditioning with 250 cGy of TBI and r.o.…”

“…pretransplant conditioning with sublethal irradiation [19,23,26,[32][33][34][35][36][37][38][39][40], (ii.) targeted reduction of murine natural killer (NK) cell activity with antibodies directed towards specific cell membrane markers (anti-asialo-GM1 [19,[33][34][35] or anti-CD122 [23,36,39]), (iii.)…”

“…targeted reduction of murine macrophages with clodronate-containing liposomes [37], (iv.) using newborn mice which lack a fully developed innate immune system [32], (v.) administration of interleukin-15 (IL-15) [38,40], and/or (vi.) generating new mouse strains with additional defects in the innate immune system [37].…”

Dendritic cell-derived interleukin-15 is crucial for therapeutic cancer vaccine potency

“…Regulated provision of transgene IL-15 in this manner may also obviate, or at least reduce, potential adverse events associated with nonspecific overexpression of transgene IL-15 in vivo. [14][15][16][17] We observed that DCIL-15 was superior to rIL-15 in promoting both murine and human DC functionality and therapeutic cancer vaccine efficacy in multiple distinct and clinically-relevant murine tumor models ( 10 , Figs. 1-6 (Fig.…”

“…[6][7][8][9][10][11][12] Unfortunately, high-doses of IL-15 (necessary for its bioactivity in vivo) via systemic administration of recombinant IL-15 protein (rIL-15) or overexpression of transgene IL-15 have untoward side-effects [e.g., stimulating tumor cell growth, activating negative regulators (e.g., programmed death-1) in CD8 C T cells, exacerbating xenogeneic graft-vs.-host-disease or autoimmunity, and functioning as an "oncogene" resulting in progressive CD8 C T or NK leukemia], [13][14][15][16][17] which have served to limit its benefit-to-risk ratio in the clinic, despite pre-clinical findings supporting the safety of rIL-15 in rhesus macaques. 18 IL-15 agonists (e.g., IL-15/IL15Ra-Fc complex and IL-15/IL-15Ra fusion protein) reduce the dose of delivered IL-15 required to reach biologicallymeaningful levels in vivo.…”