Biomedical subjects

S Ostrand-Rosenberg

Publications and source records attributed to S Ostrand-Rosenberg.

At least 37 records · Page 2Linked to original sources

PubMed1994

Tumor immunotherapy: the tumor cell as an antigen-presenting cell.

Increased knowledge in basic immunology has led to a variety of innovative and imaginative approaches for tumor-specific immunotherapy. One of these approaches is based on the premise that tumor cells do not normally stimulate an effective tumor-specific immune response, because they do not efficiently present tumor antigens to the relevant lymphocytes. To overcome inadequate antigen presentation, it has been hypothesized that tumor cells can be genetically engineered to present tumor peptides directly to T lymphocytes.

Animals↗

PubMed1993

Beta 2M-/- knockout mice contain low levels of CD8+ cytotoxic T lymphocyte that mediate specific tumor rejection.

C57BL/6 mice with a disrupted beta 2M gene (beta 2M-/- mice) express very low levels of MHC class I molecules and are deficient for CD8+ T lymphocytes. Because CD8+ T cells are thought to be a principle effector cell in tumor rejection, we have assessed the ability of beta 2M-/- mice to respond to tumors. beta 2M-/- knockout mice were challenged with seven independent MHC allogeneic and syngeneic tumors. The beta 2M-/- mice responded very similarly to their CD8+ beta 2M+/- littermates in that they rejected high dose challenges of 4/5 allogeneic tumors and were susceptible to 3/3 syngeneic tumors. In vivo depletion of CD4+ or CD8+ cells from the beta 2M-/- mice resulted in susceptibility to allogeneic tumor. The apparent requirement for CD8+ cells for tumor immunity was corroborated by in vitro assays in which depletion of CD8+ but not CD4+ T cells eliminated tumor-specific CTL activity. mAb blocking studies in which target tumor cells were incubated with MHC class I-specific mAb demonstrated that the tumor-specific CD8+ activity was MHC class I restricted. beta 2M-/- mice therefore contain very small quantities of potent, CD8+ T cells that are capable of rejecting large challenges of allogeneic tumor cells.

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PubMed1993

Constitutive expression of B7 restores immunogenicity of tumor cells expressing truncated major histocompatibility complex class II molecules.

The inability of the autologous host to reject resident tumor cells is frequently the result of inadequate generation of tumor-specific T cells. Specific activation of T cells occurs after delivery of two signals by the antigen-presenting cell. The first signal is antigen-specific and is the engagement of the T-cell antigen receptor by a specific major histocompatibility complex antigen-peptide complex. For some T cells, the second or costimulatory signal is the interaction of the T-cell CD28 receptor with the B7 activation molecule of the antigen-presenting cell. In the present study, we demonstrate that mouse sarcoma cells genetically engineered to provide both T-cell activation signals stimulate potent tumor-specific CD4+ T cells that cause rejection of both engineered and wild-type neoplastic cells. Two other recent studies have also demonstrated that costimulation via B7 can improve tumor immunity. However, our study differs from these reports by two important observations. (i) One of these studies utilized mouse tumor cells expressing xenogenic viral antigens, and hence, the results are not applicable to wild-type resident tumors. Our study, however, demonstrates that coexpression of B7 by major histocompatibility complex class II+ tumor cells induces immunity in the autologous host that is specific for naturally occurring tumor antigens of poorly immunogenic tumors. (ii) In both earlier studies, only CD8+ T cells were activated after coexpression of B7, whereas in the present report, tumor-specific CD4+ T cells are generated. This report therefore illustrates the role of B7 activation molecule in stimulating potent tumor-specific CD4+ T cells that mediate rejection of wild-type tumors and provides a theoretical basis for immunotherapy of established tumors.

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PubMed1993

Tumor cells expressing major histocompatibility complex class II and B7 activation molecules stimulate potent tumor-specific immunity.

In previous studies we have shown that the highly malignant mouse SaI sarcoma can be converted into an immunogenic tumor that is immunologically rejected by the autologous host if the tumor cells are transfected with and express syngeneic major histocompatibility complex (MHC) class II genes. Tumor cells expressing class II heterodimers truncated for the cytoplasmic regions of the alpha and beta chains, however, are as malignant as wild-type class II- tumors. These studies have contributed to the hypothesis that T-cell activation requires two signals: the engagement of the MHC class II/peptide complex of the antigen-presenting cell (APC) by the T cell receptor for antigen of the responding T cell and the transmittal of a second, or costimulatory, signal by the APC to the responding T cell. In this report we show that induction of tumor-specific immunity is facilitated by delivery of a costimulatory signal provided by the B7 activation molecule. Mice challenged with SaI cells bearing truncated class II molecules and transfected with B7 cDNA are immune to the transfectants and are protected against a challenge of wild-type class II-B7- ascites or solid SaI tumor. The induced immunity requires CD4+ T cells and is specific for the immunizing sarcoma cells. These results highlight the critical role of the B7 costimulatory pathway in stimulating long-term, tumor-specific immunity that is effective against high doses of challenging wild-type tumor and suggest a strategy for enhancing tumor rejection.

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PubMed1992

Invariant chain alters the malignant phenotype of MHC class II+ tumor cells.

T lymphocytes usually recognize endogenously encoded Ag in the context of MHC class I molecules, whereas exogenous Ag is usually presented by MHC class II molecules. In vitro studies in model systems suggest that presentation of endogenous Ag by class II molecules is inhibited by the association of class II with its invariant chain (Ii). In the present study we test this hypothesis in an in vivo system in which endogenously encoded tumor peptides are presented by tumor cell MHC class II molecules. In this system, transfection of syngeneic MHC class II genes (Aak and Abk) into a highly malignant, Ii negative, mouse tumor (SaI sarcoma) produces an immunogenic tumor (SaI/Ak) that is rejected by the autologous host. The class II+ transfectants also effectively immunize autologous A/J mice against a subsequent challenge of wild-type class II- tumor cells. We have hypothesized that the SaI/Ak transfectants induce protective immunity because they function as APC for endogenously synthesized tumor peptides, and thereby stimulate tumor-specific Th cells, by-passing the need for professional APC. To test the role of Ii as an inhibitor of presentation of endogenous peptides, SaI/Ak tumor cells were supertransfected with Ii gene (SaI/Ak/Ii cells), and the tumorigenicity of the resulting cells determined. Nine SaI/Ak/Ii clones were tested, and their malignancy compared with that of SaI/Ak and SaI cells. Seven of the nine class II+/Ii+ tumor cells are more malignant than class II+/Ii- tumor cells in autologous A/J mice. Expression of Ii therefore restores the malignant phenotype, presumably by preventing presentation of endogenously synthesized tumor peptides. Ii therefore regulates Ag presentation and can be a critical parameter for in vivo tumor immunity.

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PubMed1991

Abrogation of tumorigenicity by MHC class II antigen expression requires the cytoplasmic domain of the class II molecule.

Transfection of syngeneic MHC class II genes into the lethal mouse SaI tumor abrogates the malignancy of the tumor in the autologous host, and protects the host against subsequent challenges with the wild type class II- tumor. We have hypothesized that the transfectants induce protective immunity by functioning as APC for tumor peptides, and stimulating tumor-specific Th cells. Recent in vitro studies suggest that Ag presentation by class II-restricted APC requires the cytoplasmic domain of the class II molecule, and may involve intracellular signaling via the cytoplasmic domain. To determine if the class II cytoplasmic domain is required for enhanced tumor-specific immunity, SaI mouse sarcoma cells were transfected with syngeneic Aak and Abk genes with truncated cytoplasmic domains. These transfectants are as malignant as wild type class II- SaI cells in autologous A/J mice. Stimulation of tumor-specific immunity by class II+ tumor cells is therefore dependent on the class II cytoplasmic region, and may involve intracellular signaling events.

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PubMed1991

Tumor-specific immunity can be enhanced by transfection of tumor cells with syngeneic MHC-class-II genes or allogeneic MHC-class-I genes.

Mouse Sal sarcoma cells are lethal in the autologous A/J (KkDd) host. In order to improve the immune response to the Sal tumor, Sal cells have been transfected with syngeneic MHC-class-II or allogeneic MHC-class-I genes. MHC-class-II transfectants are uniformly rejected by the autologous host and immunization with them protects against subsequent Sal challenge. The improved immunity is probably the result of enhanced generation of tumor-specific Th cells. We hypothesize that class-II tumor cells trigger an improved Th-cell response because they directly present Sal tumor antigens in the context of class-II molecules to Th cells, by-passing professional APC. Studies by others have demonstrated that antigen presentation requires an intracellular signal transmitted by the cytoplasmic domain of the APC class-II molecule. Sal cells expressing class-II antigens with truncated cytoplasmic domains are as malignant as wild-type Sal cells. These experiments therefore support the role of tumor-cell class-II molecules as antigen presentation elements, and demonstrate the requirement for intact class-II molecules for tumor protection. Sal cells have also been transfected with allogeneic MHC-class-I genes. Although Kb-transfected cells are not rejected by A/J mice, Db-transfected Sal cells and Kb- plus Db-transfected cells are rejected. The Db transfectants effectively immunize A/J mice against subsequent Sal challenge. These experiments demonstrate that expression of certain allogeneic MHC-class-I genes can lead to tumor-specific immunity, and that such transfectants can protect against challenges of wild-type tumor cells. Transfection of tumor cells with syngeneic MHC-class-II or allogeneic MHC-class-I genes may therefore be a potential strategy for improving tumor-specific immunity in the autologous host.

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PubMed1991

Rejection of allogeneic tumor is not determined by host responses to MHC class I molecules and is mediated by CD4-CD8+ T lymphocytes that are not lytic for the tumor.

In previous studies, the murine SaI (A/J derived, KkDd) sarcoma was transfected with the allogeneic MHC class I H-2Kb gene, and expressed high levels of H-2Kb antigen. Contrary to expectations, the tumor cells expressing the alloantigen (SKB3.1M tumor cells) were not rejected by autologous A/J mice. Because these results contradict the laws of transplantation immunology, the present studies were undertaken to examine the immunogenicity of SKB3.1M and SaI cells in allogeneic hosts. Similar to SKB3.1M, SaI cells are lethal in some allogeneic strains, despite tumor-host MHC class I incompatibilities. Tumor challenges of SKB3.1M and SaI cells, however induce MHC class I-specific antibodies and CTL in both tumor-resistant and -susceptible hosts. Although the tumors induce specific CTL, tumor cells are not lysed in vitro by these CTL, suggesting that the tumor cells are resistant to CTL-mediated lysis. Since growth of these tumors does not follow the classical rules of allograft transplantation, and because the tumor is not susceptible to CTL-mediated lysis, we have used Winn assays to identify the effector lymphocyte(s) responsible for SaI rejection. Depletion studies demonstrate that the effector cell is a CD4-CD8+ T lymphocyte. Collectively these studies suggest that the host's response to MHC class I alloantigens of SKB3.1M and SaI cells does not determine tumor rejection, and that effector cells other than classically defined CTL, but with the CD4-CD8+ phenotype, can mediate tumor-specific immunity.

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PubMed1991

Mouse Hepa-1 tumor is rejected by H-2Db-restricted CTL despite decreased MHC class I antigen expression.

It has recently been hypothesized that tumor cells with reduced levels of MHC class I antigens are more susceptible to NK-mediated lysis and are rejected by NK cells, whereas tumor cells with normal levels of class I are rejected by tumor-specific CTL. We have tested this hypothesis using a mouse hepatoma system. The Hepa-1 tumor is a spontaneous H-2Kb loss variant that arose from the BW7756 tumor, when BW7756 was adapted to growth in culture. Our studies have shown that despite the loss of H-2Kb antigen, Hepa-1 is not more susceptible to NK lysis than its H-2Kb-transfected variants. These studies also suggested that NK cells were not responsible for rejection of the Hepa-1 tumor. The Hepa-1 tumor, therefore, appears to contradict the hypothesized linkage of MHC levels and NK susceptibility. Because NK cells are not involved in immunity to this tumor, we have sought to identify the effector cell responsible for Hepa-1 rejection. Cytotoxic T lymphocyte assays demonstrate that in vitro, Hepa-1 cells are lysed by Hepa-1-specific H-2Db-restricted CD4-CD8+ T lymphocytes. Footpad assays demonstrate that in vivo, Hepa-1 rejection requires CD4+CD8- and CD4-CD8+ Hepa-1-primed splenocytes. These results indicate that immunity to Hepa-1 is T cell mediated. Hepa-1 is therefore an example of an unusual tumor in that down-regulation of MHC class I antigen expression is associated with increased CTL susceptibility.

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PubMed1991

Recognition of MHC TL gene products by gamma delta T cells.

We have studied the ligand specificity of a gamma delta T-cell receptor (TCR) derived from a mouse T-cell hybridoma (KN6). KN6 cells reacted with syngeneic (C57BL/6) cells from various origins (splenocytes, thymocytes, peritoneal exudate cells, etc.) and cells from many different mouse strains. KN6 reactivity against cells from a panel of congenic and recombinant mouse strains demonstrated that the ligand recognized by KN6 is controlled by an MHC-linked gene that most probably maps in the TL region. We cloned this gene and formally proved that it does map in the TL region. This gene turned out to be a novel class I gene (designated T22b) belonging to a hitherto unidentified cluster of TL region genes in strain C57BL/6. This gene was expressed in many different tissues and cell types. We also examined the tissue expression of several other TL genes. One of these, the structural gene (T3b) encoding the thymus leukemia (TL) antigen from C57BL/6 mice, was specifically expressed in the epithelium of the small intestine. Since the intestinal epithelium of the mouse is known to be the homing site for a subset of gamma delta T cells (i-IEL) bearing diverse TCR with V7 rearranged gamma chains, we propose that the T3b gene product is part of the ligand recognized by some of the i-IEL. Our data support the idea that gamma delta T cells might be specific for non-classical class I or class I-like molecules and suggest that gamma delta TCR and non-classical MHC co-evolved for the recognition of a conserved set of endogenous or foreign peptides.

Age Factors↗

PubMed1991

Influence of major histocompatibility complex class I, class II and TLA genes on tumor rejection.

T lymphocytes recognize antigen associated with MHC class I and/or class II gene products. Recognition of malignant cells is therefore dependent on presentation of tumor associated antigen(s) by MHC molecules. We have studied immunity to tumors that have down-regulated class I expression. These studies demonstrate a requirement for class I antigens, but suggest that additional factors may also be required for tumor-specific immunity. The MHC also encodes TLA class I antigens, whose function is unknown. Our studies suggest that these molecules function is unknown. Our studies suggest that T lymphocytes, specifically in tumor cells that do not express H-2K or H-2D moieties. Other studies are aimed at improving tumor-specific Th cell generation by producing class II+ tumor cells. The success of these experiments indicates that this approach may be a potentially useful immunotherapy.

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PubMed1990

Rejection of mouse sarcoma cells after transfection of MHC class II genes.

Th cells are stimulated by peptide Ag presented in the context of MHC class II molecules. We have reasoned that immune responses against tumors may be more efficient if tumor cells were class II Ag positive, and thereby able to directly function as APC to stimulate tumor-specific Th cell proliferation. We have tested this hypothesis by using DNA-mediated gene transfer to generate syngeneic MHC class II Ag-expressing mouse Sal sarcoma cells (Sal/Ak transfectants). Autologous A/J mice challenged i.p. or s.c. with Sal/Ak transfectants do not develop tumors, whereas A/J mice challenged with the class II negative parental Sal tumor have a high tumor incidence. Furthermore, immunization of the autologous host with Sal/Ak transfectants completely protects against subsequent challenge with wild-type Sal cells. MHC class II-expressing tumor cells, therefore, stimulate an improved tumor-specific immune response, and the immunity is cross-reactive with the class II negative tumor. Inasmuch as the transfected MHC class II gene product is not functioning as a target molecule for autologous tumor rejection, the improved immunogenicity of the Sal/Ak cells is probably due to stimulation of a tumor-specific Th cell population. The increased immunogenicity of Sal/Ak cells is, therefore, probably the result of direct presentation of Sal tumor-associated Ag in the context of tumor cell MHC class II molecules to Th lymphocytes. These studies demonstrate that induction of tumor cell MHC class II Ag expression is a potential strategy for tumor-specific immunotherapy, and suggest that tumor immunity may be enhanced by improved Th cell generation.

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PubMed1990

Transfection and expression of syngeneic H-2 genes does not reduce malignancy of H-2 negative teratocarcinoma cells in the autologous host.

Rejection of the MHC class I negative 402AX teratocarcinoma is accompanied by induction of tumor cell-encoded H-2K and H-2D antigens by the genetically resistant host. To determine whether MHC antigen expression is required for 402AX rejection, we have prepared H-2Db-transfected 402AX cells (402AX/Db). Transfectants express high levels of H-2Db, most of which is not associated with beta 2-microglobulin. MHC syngeneic and allogeneic mice susceptible to 402AX are resistant to 402AX/Db, suggesting that MHC class I antigen expression is required for tumor rejection. Autologous 129 hosts, however, are susceptible to 402AX/Db. 402AX cells transfected with the H-2Kb gene (402AX/Kb) are also lethal in the autologous 129/J host, but rejected by MHC syngeneic and allogeneic mice. Non-129 strain 402AX-susceptible mice pre-immunized with 402AX/Db or simultaneously challenged with 402AX/Db plus 402AX are immune to 402AX. Mice immunized with 402AX/Db produce MHC class I induction factor. 402AX/Db and 402AX cells are lysed equally by natural killer cells, indicating that in 402AX cells the expression of class I antigens is unrelated to NK susceptibility. These studies confirm the requirement for class I expression in 402AX immunity, but demonstrate that in the autologous host immunity requires additional factors beyond class I antigen expression.

Animals↗

PubMed1989

Embryonal carcinoma cells express Qa and Tla class I genes of the major histocompatibility complex.

The murine major histocompatibility complex encodes H-2K and H-2D transplantation antigens and other class I-like proteins called Qa and Tla molecules; the functions of the Qa/Tla molecules are not known. That they may participate in embryonic cell-cell interactions and/or play a role in immune responses against tumors has been speculated. We have studied two murine embryonal carcinoma tumors, 402AX and PCC4, that are rejected in vivo immunologically, although they do not express H-2K or H-2D antigens. Transplantation studies with these cells suggest that rejection is mediated by class-I-like major histocompatibility complex antigens. As a first step in evaluating Qa/Tla function(s), we have characterized expression of class I-like genes and proteins in 402AX and PCC4 cells. Northern (RNA) blot hybridizations, polymerase chain reaction studies, and cDNA cloning experiments demonstrate that EC lines transcribe genes allelic to the Tla region gene "37", Qa-2 region gene "Q7", and another, previously uncharacterized, class I-like gene. Immunoprecipitation studies show that the embryonal carcinoma tumor cells contain low levels of beta 2-microglobulin expressed in association with non-H-2K, non-H-2D class I-like proteins.

Amino Acid Sequence↗

PubMed1988

H-2Kb antigen expression has no effect on natural killer susceptibility and tumorigenicity of a murine hepatoma.

Recent reports suggested a correlation between decreased expression of tumor cell MHC class I Ag and increased susceptibility to NK cells. These studies led to the hypothesis that tumor cells displaying reduced levels of MHC class I Ag have reduced tumorigenicity in vivo because they are eliminated from the host by endogenous NK cells. The present studies use the murine hepatoma BW7756 and a spontaneous H-2Kb loss variant, Hepa-1, to test this hypothesis. The parental BW7756 tumor is highly malignant in syngeneic C57L/J hosts while Hepa-1 cells do not give rise to tumors, suggesting that the loss of H-2Kb Ag expression correlates with decreased tumorigenicity and NK susceptibility. Hepa-1 cells were therefore transfected with an H-2Kb gene to generate H-2Kb Ag expressing clones. The resulting clones were tested for tumorigenicity. Syngeneic or NK-deficient C57BL/6-beige/beige mice challenged with Hepa-1 or the H-2Kb transfectants rejected the cells, suggesting that reexpression of H-2Kb Ag does not restore tumorigenicity and that NK cells are not involved in Hepa-1 rejection. In vitro H-2Kb Ag-negative and -positive Hepa-1 cells are equally susceptible to tilorone-boosted NK cells, indicating that MHC class I Ag expression also does not affect in vitro NK susceptibility. Tumor challenged athymic nude and sublethally irradiated syngeneic mice develop tumors demonstrating that T cells are probably responsible for rejection of the Hepa-1 tumor, and that H-2Kb Ag expression has no effect on rejection. Inasmuch as the expression of H-2Kb Ag on Hepa-1 cells does not effect tumorigenicity or in vitro NK susceptibility, the previously reported association between reduced MHC class I Ag levels and increased NK susceptibility is not universally applicable.

Animals↗

PubMed1988

Endogenous superoxide dismutase and catalase activities and radiation resistance in mouse cell lines.

The relationship between the endogenous cytoplasmic levels of the enzymes superoxide dismutase and catalase and the inhibition of cell proliferation by radiation has been studied in 11 mouse cell lines. The resistance of these mouse cell lines to radiation was found to vary by over 25-fold. No correlation was found between the cytoplasmic level of CuZn-superoxide dismutase or catalase and the resistance to radiation as measured by extrapolation number (EN), quasi-threshold dose (Dq), or DO. None of the cell lines had detectable cytoplasmic Mn-superoxide dismutase. The apparent Ki of potassium cyanide for mouse CuZn-superoxide dismutase was determined (Ki = 6.5 mumol dm-3).

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PubMed1987

Resistance to 402AX teratocarcinoma involves immunity to minor histocompatibility antigens.

The 402AX teratocarcinoma is a 129/J-derived mouse major histocompatibility complex (MHC) antigen negative tumor that is induced to express H-2b class I antigens during rejection. Resistance to 402AX by MHC allogeneic and syngeneic mice is immunologically mediated and involves the recognition of tumor-associated antigens (TAA) in the context of induced MHC class I antigens. The current studies were undertaken to define the 402AX TAAs. Reconstitution of irradiated susceptible hosts (129/J) with 402AX-primed resistant spleen cells (C57BL/6) results in acute graft-versus-host disease, suggesting that tumor-primed C57BL/6 splenocytes are reactive to tumor genotype (129/J) minor histocompatibility (Hm) antigens. C57BL/6 anti-129/J effector cells, although not directly cytotoxic for 402AX cells, are specifically cold target inhibited by 402AX cells. Genetically susceptible hosts (C3H.SW) immunized to 129/J Hm antigens by skin grafting become resistant to an i.p. challenge of 402AX cells. These results suggest that 129/J Hm antigens may be the TAAs recognized during genetically controlled rejection of the 402AX teratocarcinoma.

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PubMed1987

Allogeneic H-2 antigen expression is insufficient for tumor rejection.

Murine A strain (KkDdLd) sarcoma I (SaI) tumor cells have been transfected with a cloned H-2Kb gene. The resulting clones (SKB clones) stably express high levels of a molecule that is serologically and biochemically indistinguishable from the H-2Kb antigen. SKB clones are not susceptible to cytotoxic T lymphocyte-mediated lysis by H-2Kb-specific bulk, cloned, or H-2Kb-restricted lymphocytic choriomeningitis virus-specific effectors. Survival times of A/J and B10.A mice challenged i.p. with the H-2Kb-expressing transfectants and the parental SaI cells are similar, suggesting that the presence of an allogeneic major histocompatibility complex class I antigen on the surface of this tumor line is insufficient for tumor rejection.

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