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Adoptive transfer of autoimmune diabetes mellitus in biobreeding/Worcester (BB/W) inbred and hybrid rats.

Adoptive transfer of diabetes was accomplished by the injection of Con A-activated acutely diabetic BB/W rat spleen cells into immunosuppressed diabetes-resistant BB/W control rats and F1 hybrid offspring produced by BB/W X Lewis, BN, Yashida, and NEDH matings. Immune suppression methods that facilitated adoptive transfer of diabetes included neonatal thymectomy, cyclophosphamide, and splenectomy plus rabbit anti-rat lymphocyte serum injections. The successful transfer of BB/W diabetes to otherwise normal (BB/W X inbred)F1 rats and to diabetes-resistant BB/W animals suggests that antigenically normal pancreatic beta cells were destroyed by the injected effector cells. Diabetes-resistant BB/W control rats also evidenced diabetes after the injection of cyclophosphamide alone. The requirement for immunosuppression suggests that an intact immune system protects against adoptive transfer and diabetes in diabetes-resistant BB/W rats.

Animals↗

Manipulation of Th1/Th2 balance in vivo by adoptive transfer of antigen-specific Th1 or Th2 cells.

We have investigated the possibility that the Th1/Th2 balance in vivo may be modulated by adoptive transfer of Th1 or Th2 cells induced in vitro. Thl cells were induced from I-Ad-binding OVA323-339-specific T-cell receptor-transgenic (TCR-Tg) mouse spleen cells by culturing with OVA323-339 peptide and antigen presenting cells (APC) in the presence of IL-2, IL-12 and anti-IL-4 mAb. Th2 cells were induced from TCR-Tg mouse spleen cells by culturing with IL-2, IL-4 and anti-IL-12 mAb in addition to OVA323-339 plus APC. Immunomodulating activities of both Th1 and Th2 cells were determined by their effect on delayed type hypersensitivity (DTH) responses or cytokine production. No significant DTH responses (footpad swelling) were observed in untreated BALB/c mice following a single injection of OVA323-339-pulsed syngeneic spleen cells. However, adoptive transfer of Th1 cells into BALB/c mice induced strong dose dependent DTH responses in response to I-Ad-bound OVA323-339 but not unrelated peptide. In contrast, only slight DTH responses were detected in BALB/c mice transferred with Th2 cells. In parallel with the DTH responses, increased levels of serum IFN-gamma were demonstrated in mice adoptively transferred with Th1, while no significant increase was observed in Th2-transferred mice. In vitro analysis also demonstrated that both spleen cells and popliteal lymph node cells prepared from Th1-transferred mice showed Th1-type cytokine production, while cells obtained from Th2-transferred mice revealed Th2-dominant cytokine production. Such immune deviation induced by antigen-specific Th1 cells was demonstrated up to three months after cell transfer. Therefore, it may be possible to manipulate the Th1/Th2 balance in vivo by adoptive transfer of antigen-specific Th1 or Th2 cells.

Adoptive Transfer↗

S-antigen. Adoptive transfer of experimental autoimmune uveitis following immunization with a small synthetic peptide.

Experimental autoimmune uveitis was observed following the adoptive transfer of T cell lymphocytes (T cells) from Lewis rats previously immunized with a small synthetic peptide, peptide M, which corresponds to the amino acid sequence of a well-defined region of S-antigen. Prior to adoptive transfer, the T cells were restimulated in tissue culture with peptide M. Approximately five days following the intravenous administration of restimulated T cells, a severe uveitis was documented both clinically and histopathologically. Clinically, the disease was characterized by iris hyperemia followed by anterior chamber exudates and posterior iris synechiae. Histopathologically, the photoreceptor cell layer of the retina was completely destroyed. A subretinal exudate containing mononuclear cells and polymorphonuclear leukocytes was also present. In addition, the pineal glands of animals with experimental autoimmune uveitis showed inflammatory changes characterized by a lymphocytic infiltration of the subcapsular and central region of the gland. The clinical and histopathologic features of the experimental autoimmune uveitis were similar to those that develop following the adoptive transfer of T cells from Lewis rats previously immunized with S-antigen. Our results indicate that the amino acid sequence of the region of S-antigen corresponding to peptide M represents a distinct pathogenic site with the ability to adoptively transfer disease. We comment on the significance of this finding with regard to T cell-mediated immune mechanisms in certain forms of human uveitis.

Amino Acid Sequence↗

Effects of polyinosinic-polycytidylic acid and adoptive transfer of immune cells in the Lew.1AR1-iddm rat and in its coisogenic LEW.1AR1 background strain.

The importance of the cellular immune system for the development of T1DM in the LEW.1AR1-iddm rat was investigated by use of polyinosinic-polycytidylic acid (Poly I:C) and by adoptive transfer of concanavalin A (Con A) activated lymphocytes from diabetic LEW.1AR1-iddm rats and the coisogenic LEW.AR1 background strain. Poly I:C treatment induced diabetes, characterized morphologically by a diffuse infiltration of the pancreas, in up to 20% of the animals of the coisogenic LEW.1AR1 background strain. It did not increase the diabetes incidence of 30% of the LEW.1AR1-iddm strain. In contrast Poly I:C treatment induced diabetes in up to 80% of the animals of the Mhc congenic LEW.1WR1 strain. Adoptive transfer of lymphocytes activated by the T-cell mitogen Con A from diabetic donors doubled the incidence of diabetes, characterized morphologically by a focal insulitis, in diabetes prone LEW.1AR1-iddm recipients. In contrast, animals of the LEW.1AR1 background strain did not develop diabetes after adoptive transfer. Moreover, adoptive transfer of Con A activated lymphocytes from LEW.1AR1 rats to LEW.1AR1-iddm rats with 30 or 60% diabetes incidence, significantly decreased the incidence of diabetes in LEW.1AR1-iddm rats with 60% diabetes incidence. The results show that autoreactive lymphocytes induce beta cell destruction in the LEW.1AR1-iddm rat, while the LEW.AR1 background strain apparently contains regulatory potential, which is able to counteract the autoimmune response.

Adoptive Transfer↗

Pathogenesis of experimental allergic orchitis. III. T lymphocyte requirement in local adoptive transfer by peritoneal exudate cells.

In experimental allergic orchitis (EAO), a lesion characterized by mononuclear invasion of seminiferous tubules can be adoptively transferred within 1 to 4 days by testicular injection of peritoneal exudate cells (PEC) from syngeneic strain 13 guinea pigs (GP) immunized with homologous testicular antigens in complete Freund's adjuvant (CFA). This study examined the role of T lymphocytes, macrophages, and polymorphonuclear neutrophils (PMN) in the adoptive transfer. Guinea pig PEC contained 7% T lymphocytes, rare B lymphocytes, and over 90% of macrophages and PMN. After T lymphocytes were depleted by rabbit erythrocyte (E) rosette and Hypaque-Ficoll gradient centrifugation, cell preparations that contained 73% of original macrophages and 15% original T lymphocytes were obtained, and these cells did not transfer EAO (0 of 18 testes). In contrast, cell preparations enriched in T lymphocytes by nylon wool column or E rosette contained 1.5% of the original macrophages and 59% of the original T lymphocytes transferred EAO to 70% of the testes, starting at 1.5 x 10(6) T lymphocytes per testis. The number of T lymphocytes correlated with the incidence of adoptive transfer; the correlation existed regardless of the number of macrophages or PMN present. Finally, EAO was adoptively transferred to recipients that had total-body irradiation. The results indicate that (a) T lymphocytes are capable of transferring lesions of EAO, (b) in the transfer, the T lymphocytes did not function as helper T cells, since the transfer need not involve participation of host lymphoid cells, and (c) by inference, testis antigen-reactive T lymphocytes exist.

Animals↗

Adoptive transfer of in vitro-stimulated CD4+CD25+ regulatory T cells increases bacterial clearance and improves survival in polymicrobial sepsis.

Regulatory CD4(+)CD25(+) T cells (Tregs) suppress autoimmune and inflammatory diseases through mechanisms that are only partly understood. Previous studies suggest that Tregs can suppress bacterially triggered intestinal inflammation and respond to LPS through TLRs with enhanced suppressive activity. In this study, we have used murine cecal ligation and puncture as a model of polymicrobial sepsis to explore the effects of adoptive transfer of Tregs on septic outcome. Adoptive transfer of in vitro-stimulated Tregs in both prevention and therapeutic modes significantly improved survival of cecal ligation and puncture mice. Furthermore, the effect was dependent on both the number of Tregs adoptively transferred and the presence of host T cells. Animals that received stimulated Tregs had significantly increased peritoneal mast cells and peritoneal TNF-alpha production. More importantly, adoptive transfer of in vitro-stimulated Tregs significantly improved bacterial clearance, which resulted in improved survival. Our results suggest a novel role for Tregs in sepsis.

Adoptive Transfer↗

IL-4, IL-10, IL-13, and TGF-beta from an altered peptide ligand-specific Th2 cell clone down-regulate adoptive transfer of experimental autoimmune encephalomyelitis.

Experimental autoimmune encephalomyelitis (EAE) is induced in the SJL/J mouse by adoptive transfer of activated proteolipid protein peptide (PLP) 139-151-specific Th1 cells. T cells responding to altered peptide ligands (APL) of PLP, previously shown to induce Th2 differentiation and regulate disease in PLP-immunized mice, do not transfer EAE. However, the exact mechanism of disease regulation by APL-specific T cells has not been elucidated. In this report, we show that 1F1, a Th2 clone specific for an APL of PLP139-151 can prevent adoptive transfer of EAE when cocultured with PLP-encephalitogenic spleen cells (PLP-spleen). Cytokines from activated 1F1 cells were detected by hybridization of mRNA to oligonucleotide arrays (DNA chip) and by ELISA. The Th2 cytokines found to be present at the highest protein and mRNA levels were evaluated for their role in suppression of adoptive transfer of EAE from PLP-activated spleen cell cultures. Abs to individual cytokines in 1F1 PLP-spleen cocultures suggested that IL-4, IL-13, and TGF-beta played a significant role in suppressing EAE. Abs to the combination of IL-4, IL-10, IL-13, and TGF-beta completely neutralized the protective effect of 1F1. Addition of Th2 cytokines to PLP-spleen cultures showed that IL-13 and TGF-beta were each individually effective and low levels of IL-4 synergized with IL-13 to inhibit disease transfer. IL-5, IL-9, and IL-10 had little or no effect whereas GM-CSF slightly enhanced EAE. Our results demonstrate that Th2 cytokines derived from APL-specific Th2 cells can effectively down-regulate the encephalitogenic potential of PLP-spleen cells if present during their reactivation in culture.

Adoptive Transfer↗

Activation of "eclipsed" lymphoid cells from advanced tumor-bearing mice through adoptive transfer to sublethally irradiated syngeneic hosts.

Immunologically inactive or "eclipsed" lymphoid cells from advanced tumor-bearing mice were investigated following their adoptive transfer to irradiated syngeneic hosts. Experiments were performed with two syngeneic tumor-host system: the T5-BALB/c tumor line chronically infected with a low-leukemogenic Rauscher virus variant and the TM1-C3H tumor line developed from a spontaneous C3H/He mouse mammary tumor. In confirmation of our previous data, peritoneal cells (PC) from advanced tumor-bearing mice (EPC) appeared to have lost any capacity to inhibit specifically the growth of corresponding tumor target cells in vitro colony inhibition (CI) tests, whereas PC from immunized mice (IPC) were perfectly active. When these EPC were adoptively transferred by intraperitoneal inoculation into sublethally irradiated (450 R) syngeneic mice in association with respective tumor extracts (TE), the PC from such recipient mice, taken 5 to 13 days later, were nearly as active in in vitro CI tests as were PC from parallel IPC-recipient mice. For this recovery of specific immunological activity following the adoptive transfer of EPC the adjunction of the TE and irradiation of the recipient animals seem important and may be necessary. On the other hand, no specific immunological activity was seen in PC from irradiated mice to which PC from normal mice had been transferred with TE. In addition to the in vitro results, an effect of adoptive transfer of EPC (retardation of tumor growth) was also observed in vivo. It is concluded that the "eclipsed" immunologically inactive state of the EPC in mice bearing advanced tumor is not irreversible and that activation of these cells can occur in vivo under certain conditions helped by the presence of tumor-specific antigenic stimulus.

Animals↗

Adoptive transfer of gut intraepithelial lymphocytes protects against murine infection with Toxoplasma gondii.

Intraepithelial lymphocytes (IEL) of the gut represent a primary immune barrier against infection by orally acquired pathogens. Naturally acquired infection with Toxoplasma gondii induces the proliferation of CD8+ T cells in both the gut and spleen. Gut-derived CD8alpha/beta+ IEL exhibit MHC-restricted cytotoxicity against parasite-infected enterocytes and macrophages. In a murine model, we demonstrate that the adoptive transfer of IEL obtained from inbred mice at day 11 postinfection is able to protect against a virulent challenge in syngenic recipients. In CBA mice, the parasite cyst load within the brain of the recipients receiving primed IEL was reduced by 90%. In BALB/c and C57BL/6 mice, a 50% decrease in mortality was observed following adoptive transfer of primed IEL. To determine the T cell subset responsible for protective immunity, a purified CD8alpha/beta+ IEL population was isolated from infected mice at day 11 postinfection. These cells were able to protect naive mice by adoptive transfer against a lethal parasite challenge. RNA analysis by reverse-transcriptase PCR revealed that primed CD8alpha/beta+ IEL produce significant message for IFN-gamma, an essential cytokine for host protection against toxoplasmosis. Administration of anti-IFN-gamma at the time of adoptive transfer of primed IEL abrogated protection. The adoptive transfer of these protective IEL was not restricted to the Ld class I locus. These data demonstrate that IFN-gamma-producing IEL may be an important primary barrier against acute and perhaps recurrent infection with T. gondii.

Adoptive Transfer↗

Rapid death of adoptively transferred T cells in acquired immunodeficiency syndrome.

Human immunodeficiency virus (HIV)-specific cytotoxic T lymphocytes (CTL) probably play the major role in controlling HIV replication. However, the value of adoptive transfer of HIV-specific CTL expanded in vitro to HIV+ patients has been limited: this contrasts with the success of CTL therapy in treating or preventing Epstein-Barr virus and cytomegalovirus disease after bone marrow transplantation (BMT). We investigated the fate of expanded HIV-specific CTL clones in vivo following adoptive transfer to a patient with acquired immunodeficiency syndrome (AIDS). Two autologous CTL clones specific for HIV Gag and Pol were expanded to large numbers (>10(9)) in vitro and infused into an HIV-infected patient whose viral load was rising despite antiretroviral therapy. The fate of one clone was monitored by staining peripheral blood mononuclear cells (PBMCs) with T-cell receptor-specific tetrameric major histocompatibility complex (MHC)-peptide complexes. Although the CTL transfer was well tolerated, there were no significant changes in CD4 and CD8 lymphocyte counts and virus load. By tracking an infused clone using soluble MHC-peptide complexes, we show that cells bearing the Gag-specific T-cell receptors were rapidly eliminated within hours of infusion through apoptosis. Thus, the failure of adoptively transferred HIV-specific CTL to reduce virus load in AIDS may be due to rapid apoptosis of the infused cells, triggered by a number of potential mechanisms. Further trials of adoptive transfer of CTL should take into account the susceptibility of infused cells to in vivo apoptosis.

Adoptive Transfer↗

Co-operative cellular interactions in the generation of adoptively-transferred murine IgA responses.

The adoptive transfer system was initially used to document the requirement for co-operation between hapten-primed and carrier-primed lymphocytes in generating secondary IgA antibody responses. Studies employing anti-theta antiserum and complement to deplete T cells showed that carrier-specific theta-bearing cells are required for IgA responses. Furthermore, non-specific T-cell help could be provided by transfer of normal allogeneic spleen cells into irradiated recipients. When limiting numbers of 'educated' thymus cells were added to a constant number of spleen cells, depleted of T cells, IgM responses were not affected while both IgG and IgA antibody responses were shown to be dependent on the numbers of thymus cells injected. These results provide direct evidence for the participation of theta-bearing T lymphocytes in IgA anti-TNP antibody responses and suggest that IgA lymphocyte precursors may be inherently more sensitive than IgM B cells to the regulatory effects of helper T lymphocytes.

Animals↗

Adoptive transfer of V beta 2-deleting activity with host cells from mice implanted with C4 preneoplastic hyperplastic alveolar nodules.

Selective deletion of mature peripheral V beta 2+ T-cells was observed in BALB/c mice implanted with the syngeneic C4 preneoplastic hyperplastic alveolar nodule (HAN) but not in mice with sham surgery (W. Z. Wei, R. Ficsor-Jacobs, S. J. Tsai, and R. Pauley, Cancer Res., 51:3331-3333, 1991). We now report the participation of host cells in that process. Peripheral V beta 2+ T-cells were reduced by 50% or more 4 weeks after an i.v. injection of 10 x 10(6) spleen cells from C4 HAN-bearing mice. Both T- and B-cell-enriched splenocytes mediated V beta 2 deletion. Secondary adoptive transfer of splenocytes from the recipients of the primary adoptive transfer also resulted in V beta 2+ T-cell deletion. The splenocytes lose V beta 2-deleting activity after 500 rad irradiation. V beta 2 deletion induced by either C4 HAN or splenocytes was more profound in CD4+ than in CD8+ T-cells. Loss of V beta 2+CD4+ T-cells was observed 5 days after the adoptive transfer of splenocytes, whereas V beta 2+ CD8+ cells were not reduced until day 9 or later. The differential rate of V beta 2+ CD4+ and CD8+ T-cell reduction continued for at least 7 weeks after the adoptive transfer. The pattern of V beta 2 deletion and the sequence of T-cell loss is similar in the recipients of C4 HAN or of adoptively transferred splenocytes. Southern blot analysis demonstrates non-germ line Mtv or MMTV proviral DNA in C4 HAN. Splenocytes of C4 HAN-bearing mice express a higher level of 1.7-kilobase long terminal repeat transcript than normal BALB/c splenocytes, suggesting a role for a unique Mtv/MMTV provirus in V beta 2 deletion.

Animals↗

Regression of extensive pulmonary metastases in mice by adoptive transfer of antigen-specific CD8(+) CTL reactive against tumor cells expressing a naturally occurring rejection epitope.

In this study, we developed a mouse model of adoptive immunotherapy reflecting immune recognition of syngeneic tumor cells naturally expressing an endogenous rejection Ag. Specifically, in a pulmonary metastases model, we examined the potency and maintenance of an antitumor CD8(+) CTL response in vivo, as well as its effectiveness against an "extensive" tumor burden. The approach taken was to first generate tumor-specific CTL from mice challenged with the CMS4 sarcoma coadministered with anti-CTLA4 mAb, which has been shown to facilitate the induction of Ag-specific T cell responses in vivo. An H-2L(d)-restricted nonamer peptide, derived from an endogenous murine leukemia provirus was identified as a CMS4-reactive CTL epitope based upon the following: CTL cross-recognition of another syngeneic tumor cell line (CT26 colon carcinoma) previously characterized to express that gene product; sensitization of Ag-negative lymphoblasts or P815 targets with the peptide; and by cold target inhibition assays. In vivo, the adoptive transfer of CMS4-reactive CTL (> or =1 x 10(6)) resulted in nearly the complete regression of 3-day established lung metastases. Furthermore, mice that rejected CMS4 following a single adoptive transfer of CTL displayed antitumor activity to a rechallenge 45 days later, not only in the lung, but also at a s.c. distal site. Lastly, the adoptive transfer of CTL to mice harboring extensive pulmonary metastases (> 150 nodules) led to a substantial reduction in tumor burden. Overall, these data suggest that the adoptive transfer of tumor-specific CTL may have therapeutic potential for malignancies that proliferate in or metastasize to the lung.

Abatacept↗

Long-term survival of adoptively transferred tumor-infiltrating lymphocytes in mice.

We examined the long term survival of adoptively transferred, cultured tumor-infiltrating lymphocytes (TIL) in sublethally irradiated nontumor-bearing mice. TIL were produced by culturing Thy-1-enriched single cell suspensions from a variety of murine tumors in exogenous IL-2 along with irradiated tumor cells and splenocytes. TIL were adoptively transferred i.v. to mice and such animals demonstrated a statistically significant degree of protection from a subsequent i.v. tumor challenge. This protection lasted up to 6 wk and occurred in the absence of exogenous IL-2 administration in vivo. Using congenic B6.PL Thy-1 alpha/CY mice we demonstrated directly that TIL can survive in vivo for up to 6 wk and that the adoptively transferred TIL were the source of the relative immunity to subsequent tumor challenge. We conclude that TIL contain cells with substantial functional longevity in vivo even in the absence of exogenous IL-2. These studies are relevant to ongoing clinical trials of TIL as a therapy for patients with advanced cancer.

Animals↗

In vivo assessment of tumor-induced nonspecific suppression of contact sensitivity. II. Regulation by cytokines and T cells via adoptive transfer.

Normal BALB/c mice were assessed for 2,4-dinitrofluorobenzene (DNFB)-induced contact sensitivity following adoptive transfer of macrophages (Mo). T cells, or their derived products, from normal or tumor-bearing hosts (TBH). Contact sensitivity (CS) was measured by a quantitative radioisotopic ear assay, a total in vivo system based on localization of IP-injected iodinated human serum albumin [( 125I]HSA) in the DNFB-challenged ear. Adoptive transfer of low or high doses of TBH T cells or their derived supernatants into normal recipients suppressed their responsiveness, while Mo supernatants enhanced it. Moreover, in all cases adoptive transfer of TBH cells or supernatants resulted in a lower CS response than did their normal counterparts. These results further corroborate our previous in vitro data indicating that T cells, or Mo and T cell soluble products, possess immunoregulatory capabilities in vivo.

Animals↗

Adoptive transfer of immunity to Nocardia asteroides in nude mice.

Nude mice on a BALB/c background were adoptively transferred with unprimed spleen cells, Nocardia-primed spleen cells, or Nocardia-primed splenic T lymphocytes from syngeneic, heterozygous (nu/+) littermates. Two days later, these recipient mice and unmanipulated (control) nude mice were infected intravenously with a 50% lethal dose of Nocardia asteroides GUH-2 from an early stationary-phase culture. Antibody titers, spleen weights, percent mortality, and organ clearance of the microorganisms were measured at 3 h to 28 days after infection. Adoptively transferred nude mice had larger spleens and greater titers of anti-nocardial antibody 7 to 28 days after infection as compared with control nude mice. Adoptive transfer with either primed spleen cells or primed splenic T lymphocytes enhanced both the survival of recipient nude mice and their ability to eliminate N. asteroides from the liver and spleen. These data indicate that adoptive immunity to infection with N. asteroides can be transferred with either specifically primed spleen cells or splenic T lymphocytes. Thus, it appears that cell-mediated immunity and T lymphocytes are of uppermost importance in host resistance to nocardial infection.

Animals↗

Retention of adoptively transferred interleukin-2-activated natural killer cells in tumor tissue.

BACKGROUND: Adoptively transferred interleukin-2 activated natural killer (A-NK) cells are capable of selectively infiltrating tumor, however, only at low efficiency. The aim of this study was to investigate the intratumoral A-NK cell retention using an ex-vivo tissue-isolated tumor preparation. METHODS: R3230AC mammary adenocarcinoma and CSE fibrosarcoma were implanted in the ovarian fat pad of Fisher 344 rats. The tumors were perfused ex vivo 14 to 15 days post-implant with a known number of fluorescent labelled A-NK cells, and the effluent collected serially over time. Non stimulated splenocytes (N-SS) were used as controls. RESULTS: In group 1, tumors were perfused with either A-NK (n = 16) or N-SS (n = 7) cells. The mean number of the cells which remained intratumorally at the completion of the perfusion was 48.37% +/- 14.94 for A-NK cells and 34.68% +/- 13.20 of N-SS (p = 0.048). In group 2, tumors were perfused with a suspension containing both A-NK and N-SS cell (n = 11). The difference in tumor retention between A-NK cells and N-SS was 22.5% (p = 0.0053) for R3230AC tumors (retention of intratumoral A-NK cells was 45.1% +/- 6.47 vs. 22.6% +/- 19.09 for N-SS) and 15.88% (p = 0.028) for the fibrosarcomas (34.01% +/- 15.96 vs. 18.12 +/- 17.78 for A-NK and N-SS, respectively). No difference with respect to retention of A-NK cells or N-SS cells was observed between tumor types (p = 0.23 and p = 0.71, respectively). CONCLUSIONS: The retention of A-NK cells in tumor tissues was significantly better than the retention of N-SS when administered directly. Since the retention of A-NK cells in tumor tissue was high (35-50%), this factor does not explain the low efficiency of adoptively transferred A-NK cells accumulating in tumors when administered systemically.

Adoptive Transfer↗

Antigen-specific cytotoxicity and cell number of adoptively transferred T cells are efficiently maintained in vivo by re-stimulation with an antigen/interleukin-2 fusion protein.

In order to maintain in vivo anti-tumor efficacy of antigen (Ag)-specific T cells in adoptive immunotherapy for a prolonged period, we constructed a fusion protein (OVA/IL-2) containing ovalbumin (OVA) as a model tumor Ag, co-valently linked to murine interleukin-2 (IL-2). The OVA/IL-2 protein produced in a baculovirus expression system displayed potent IL-2 bio-activity. Immunization with the OVA/IL-2 protein after adoptive transfer of OVA-specific T cells maintained the OVA-specific cytotoxicity and cell number of adoptively transferred T cells long term in vivo, while a simple mixture of recombinant OVA (rOVA) and rIL-2 did not. The response was dependent on the injection doses and times of the OVA/IL-2 protein. Furthermore, weekly re-stimulation of adoptively transferred OVA-specific T cells with the OVA/IL-2 protein cured 70% of tumor-bearing mice. In contrast, re-stimulation with a mixture of rOVA and rIL-2 could not significantly prolong the survival period of tumor-bearing mice. These studies suggest that the co-valent linkage between IL-2 and antigen confines the effect of IL-2 to antigen-specific T cells, leading to efficient maintenance of the anti-tumor activity of adoptively transferred T cells.

Animals↗