Tumor cytolysis by lymphocytes infiltrating ovarian malignant ascites

Tumor-associated lymphocytes (TAL) were isolated from the ascitic fluid of patients with adenocarcinoma of the ovary. These cells proliferated and expanded by 100-600-fold as either CD3+ CD4+ or CD3+ CD8+ cultures in the presence of moderate concentrations (50-200 cetus units/ml) of recombinant interleukin 2 and reached high numbers (5 x 10(8)-1 x 10(9)). After expansion of 16 TAL samples from 15 patients, 5 of the 7 isolated ovarian cytotoxic T-lymphocyte cell lines of T-cell receptor (TCR) (alpha beta)+ CD3+ CD8+ CD4- phenotype exhibited preferential cytolytic activity against autologous tumor targets and significantly lower cytolytic activity against allogeneic tumor targets and the natural killer-sensitive cell line K562. The cytolytic activity of the CD8+ TAL was inhibited by operationally anti-TCR (alpha beta) monoclonal antibody and monoclonal antibody specific for the CD3 differentiation antigen, indicating that the TCR and CD3 are involved in the cytolytic process. The other TAL cultures demonstrated similar cytolytic activity against both autologous and allogeneic tumors. The phenotype of these TAL was predominantly TCR (alpha beta)+ CD3+ CD4+ CD8-. Certain CD3+ CD8+ T-cell clones isolated from representative TAL exhibited preferential autologous tumor-specific cytotoxicity that may be major histocompatibility complex restricted. Other CD3+ CD8+ and CD3+ CD4+ clones exhibited nonmajor histocompatibility complex restricted cytotoxicity. These results demonstrate that CD3+ CD4+ and CD3+ CD8+ T-cells present in the ovarian malignant ascites can be propagated in large numbers and for long time intervals as T-cell lines in vitro. This finding may be significant for further investigation of ovarian tumor-specific cytotoxic T-lymphocytes and future adoptive specific immunotherapy studies.     

Elimination of V beta 2 bearing T-cells in BALB/c mice implanted with syngeneic preneoplastic and neoplastic mammary lesions

The effect of growth of BALB/c C4 preneoplastic and neoplastic mammary lesions on the host T-cell repertoire was investigated. T-cells with specific V beta regions (V beta 2, -6, -8.1-2, -11, and -14) in the T-cell receptors were enumerated in C4 hyperplastic alveolar nodule (HAN)-infiltrating lymphocytes and lymph node cells from both C4 HAN and C4 tumor-bearing mice by flow cytometry with V beta-specific monoclonal antibodies. Growth of C4 HAN and tumor induced selective deletion of peripheral V beta 2+ T-cells. Elimination of V beta 2+ T-cells [7.2 +/- 0.8% (SD) of normal lymph node T-cells] by C4 HAN was biphasic and irreversible. Approximately one-half of the V beta 2+ T-cells were lost within the first month of C4 HAN implantation. Further reduction of V beta 2+ T-cells took place after another 3 months, at which time the level of V beta 2 was reduced to 1.2 +/- 0.1% of the total T-cell population. V beta 2 deletion occurred in BALB/c mice which had been implanted with C4 HAN at either 3 weeks or 2 months of age. Loss of V beta 2+ T-cells was not reversed by removal of C4 HAN. C4 tumor also induced V beta 2+ T-cell deletion. These results demonstrate a novel V beta 2 deleting activity expressed by C4 mammary lesions and suggest that during mouse mammary tumorigenesis, a unique "superantigen" is expressed which can cause profound systemic changes in the T-cell repertoire.     

Tumor gene therapy by MVA-mediated expression of T-cell-stimulating antibodies

Immune responses to tumor-associated antigens are often dampened by a tumor-induced state of immune anergy. Previous work has attempted to overcome tumor-induced T-cell anergy by the direct injection of vectors carrying the genes encoding one of a variety of cytokines. We hypothesised that the polyclonal stimulation of T cells, preferably through the TCR complex, would result in a cascade of cytokines associated with T-cell activation and would be best able to overcome T-cell anergy. Here we use the highly attenuated MVA poxvirus to express on tumor cells, in vitro and in vivo, either of three membrane-bound monoclonal antibodies specific for murine TCR complex. Using this system, we have expressed antibodies specific for the CD3 epsilon chain (KT3), TCR alpha/beta complex (H57-597), and V beta 7 chain (TR310). Tumor cells bristling with these antibodies are capable of inducing murine T-cell proliferation and cytokine production. When injected into growing tumors (P815, RenCa, and B16F10), these constructs induce the activation of immune effector cells and result in the rejection of the tumor. Histological and FACS analysis of tumor-infiltrating leukocytes reveal that the injection of recombinant virus-expressing antibodies specific for the TCR complex attracts and activates (CD25(+), CD69(+)) CD4 and CD8 lymphocytes. This approach represents a novel strategy to overcome T-cell anergy in tumors and allow the stimulation of tumor-specific T cells.     

Clinical results and characterization of tumor-infiltrating lymphocytes with or without recombinant interleukin 2 in human metastatic renal cell carcinoma

A Phase I trial of tumor-infiltrating lymphocytes (TIL) expanded in vitro and administered on Days 1 and 8, with or without continuous infusion recombinant interleukin 2 (rIL-2) in 25 patients with metastatic renal cell carcinoma, was conducted. Eighteen of the 25 eligible patients were treated with TIL and escalating doses of rIL-2 (0.0, 3.0, 4.5 x 10(6) units/m2) on Days 1 to 5 and 8 to 12. Dose-limiting toxicity was pulmonary, and the maximum tolerated dose of rIL-2 was 3.0 x 10(6) units/m2. No clinical responses were observed. Immunological monitoring of peripheral blood lymphocytes demonstrated significant increases in CD3+ and CD56+ cells, including the activated T-cell subsets. Phenotypic analysis of cultured TILs demonstrated significant heterogeneity and the presence of CD3+CD4+ and CD3+CD8+ T-cells, with CD3-CD56+ and CD3+CD56+ populations also present. The majority of cultured TILs expressed HLA-DR and CD45RO, with a variable number expressing CD25. The rIL-2-expanded TILs possessed cytotoxicity against allogeneic and autologous tumor, with cytolytic activity against only autologous tumor seen in one patient. Results demonstrate that in vitro expansion of TILs is possible, but further studies are needed to define the biology of TILs in renal cancer and to isolate and expand tumor-specific T-cells.     

Melanoma patients respond to a cytotoxic T lymphocyte-defined self-peptide with diverse and nonoverlapping T-cell receptor repertoires

HLA-A2+ melanoma patients develop naturally a strong CD8+ T cell response to a self-peptide derived from Melan-A. Here, we have used HLA-A2/peptide tetramers to isolate Melan-A-specific T cells from tumor-infiltrated lymph nodes of two HLA-A2+ melanoma patients and analyzed their TCR beta chain V segment and complementarity determining region 3 length and sequence. We found a broad diversity in Melan-A-specific immune T-cell receptor (TCR) repertoires in terms of both TCR beta chain variable gene segment usage and clonal composition. In addition, immune TCR repertoires selected in the patients were not overlapping. In contrast to previously characterized CD8+ T-cell responses to viral infections, this study provides evidence against usage of highly restricted TCR repertoire in the natural response to a self-differentiation tumor antigen.     

Analysis of T-cell immune response in renal cell carcinoma: Polarization to type 1-like differentiation pattern,clonal T-cell expansion and tumor-specific cytotoxicity

We assessed the naturally occurring T-cell immune response in primary renal cell carcinoma (RCC) tumors from 12 unselected patients. A predominance of CD3⁺ T-cell receptor (TCR)α/β⁺ T cells was observed in tumor-infiltrating lymphocytes (TILs), in contrast with peripheral blood lymphopenia found in some patients. Activation antigen expression on TILs revealed an imbalance in the activation status, with a significant percentage of CD69⁺ and HLA-DR⁺ and a low percentage of CD25⁺ and CD71⁺ TILs. The lymphocyte activation gene-3 (LAG-3) was detected in some TIL subpopulations and especially in one patient in whom TILs were predominantly TCRα/β⁺CD8⁺DR⁺LAG-3⁺. In addition, we found that RCC TILs are polarized to a global type 1-like (Th1/Tc1) differentiation pattern (strong secretion of interferon-γ and interleukin-2 (IL-2) following CD3/TCR cross-linking) but are under the influence of the down-modulatory cytokines IL-6 (secreted by tumor cells) and IL-10, within the tumor microenvironment. In 3 of 5 patients, clonal T-cell expansion at the tumor site was found for several Vβ specificities, suggesting that in situ stimulation of specific clonotypes in response to potential tumor antigens is a frequent event in RCC. Furthermore, in one patient, selective intratumor amplification of a Vβ1 subpopulation (5% of TCR α/β⁺ cells) corresponding to 2 distinct Vβ1-Jβ1.6 and Vβ1-Jβ2.3 tumor-specific MHC class I-restricted cytotoxic T lymphocytes supports the view that discrete T-cell subsets contribute readily to in situ immunosurveillance. Int. J. Cancer 72:431–440, 1997. © 1997 Wiley-Liss, Inc.     

Discordant gene and surface expression of the T-cell receptor/CD3 complex in adult T-cell leukemia cells.

Cell surface expression of the T-cell receptor (TCR)/CD3 complex on the cells from 11 acute type adult T-cell leukemia (ATL) and 4 lymphoma type ATL patients was examined by flow cytometry. Cells from 10 of 11 acute ATL patients were TCR alpha beta+ and CD3+, and their mean fluorescence intensities were low (TCR alpha beta, 25.3-84.6; CD3, 22.8-87.8). Cells from two of four lymphoma type ATL did not express this complex, and the other two were CD3+, TCR alpha beta-. In contrast, the mean fluorescence intensity of the TCR/CD3 complex in cells from a patient with T4 chronic lymphocytic leukemia was not low (TCR alpha beta, 129.9; CD3, 117.1). mRNA expressions of the TCR alpha, beta, and CD3 gamma, delta, epsilon, and zeta chains were examined by Northern blots. ATL cells from two acute and two lymphoma types expressed amounts of this complex equal to or greater than those expressed by T4 chronic lymphocytic leukemia. CD3 delta and TCR beta mRNA in ATL and T4 chronic lymphocytic leukemia cells were equally stable to actinomycin D treatment. The synthesis of CD3 zeta protein by ATL cells was detected by Western blotting assay. On the basis of these findings, we discuss the possible involvement of the TCR/CD3 complex in activation of ATL cells.     

Gamma delta T-cell neoplasms: a clinicopathological study of 11 cases.

BACKGROUND: The majority of T-cell neoplasms express T-cell antigen receptor (TCR) alpha beta on their cell surface, and a few cases show the TCR gamma delta phenotype. Recently, a variety of gamma delta T-cell neoplasm was recognized; however, its clinicopathological features have not been extensively analyzed. Here we report the results of a clinicopathological study of 11 cases of gamma delta T-cell neoplasm. PATIENTS AND METHODS: During the 11-year period from 1989 to 1999, 104 patients with T-cell neoplasms were examined by flow cytometric analysis and/or immunohistochemical analysis. Tumor cells from all 104 patients expressed one or more of the T-cell antigens-CD2, CD3, CD5 and CD7. Forty-nine of the 104 cases of T-cell neoplasms were examined immunophenotypically for TCR alpha beta/gamma delta subsets. RESULTS: Expression of TCR gamma delta on tumor cells was found in five (33%) of 15 patients with precursor T-cell lymphoblastic leukemia/lymphoma, one (25%) of four with T-cell granular lymphocytic leukemia and five (26%) of 19 with peripheral T-cell lymphoma (PTCL), whereas no expression was found in 11 patients with adult T-cell leukemia-lymphoma. Primary sites of the five patients with gamma delta PTCL were as follows: lymph node, three; skin, one and liver, tonsil and skin, one. The courses of the three patients with gamma delta PTCL of nodal onset were very short (3, 5 and 9 months, respectively), and they were all resistant to combination chemotherapies. CONCLUSIONS: Although gamma delta T-cell neoplasm constitutes a heterogeneous population, it is important to examine the expression of TCR with the view to identifying possible poor prognostic subgroups, such as primary nodal gamma delta T-cell lymphoma.     

Vaccination-induced functional competence of circulating human tumor-specific CD8 T-cells

T-cells specific for foreign (e.g., viral) antigens can give rise to strong protective immune responses, whereas self/tumor antigen-specific T-cells are thought to be less powerful. However, synthetic T-cell vaccines composed of Melan-A/MART-1 peptide, CpG and IFA can induce high frequencies of tumor-specific CD8 T-cells in PBMC of melanoma patients. Here we analyzed the functionality of these T-cells directly ex vivo, by multiparameter flow cytometry. The production of multiple cytokines (IFNγ, TNFα, IL-2) and upregulation of LAMP-1 (CD107a) by tumor (Melan-A/MART-1) specific T-cells was comparable to virus (EBV-BMLF1) specific CD8 T-cells. Furthermore, phosphorylation of STAT1, STAT5 and ERK1/2, and expression of CD3 zeta chain were similar in tumor- and virus-specific T-cells, demonstrating functional signaling pathways. Interestingly, high frequencies of functionally competent T-cells were induced irrespective of patient's age or gender. Finally, CD8 T-cell function correlated with disease-free survival. However, this result is preliminary since the study was a Phase I clinical trial. We conclude that human tumor-specific CD8 T-cells can reach functional competence in vivo, encouraging further development and Phase III trials assessing the clinical efficacy of robust vaccination strategies.     

Targeting of "T" lymphocytes against human hepatoma cells by a bispecific monoclonal antibody: role of different lymphocyte subsets.

In an attempt to construct bispecific monoclonal antibodies (bimAbs) able to target cytotoxic T lymphocytes against human hepatoma cells, an HGPRT-deficient mutant of the Hepama-6 hybridoma, which produces an antihuman-hepatoma mAb, was directly fused with splenocytes from Balb/C mice immunized by a polyclonal cytotoxic T-cell line. Hybrid hybridomas were selected in HAT medium, and their supernatants were directly screened for the ability to induce IL-2-cultured cytotoxic T lymphocytes to kill hepatoma cells in a 51Cr-release assay. The selected hybrid hybridoma, termed DQ-33, secretes a bimAb, which reacts with a CD3-associated determinant. When resting peripheral-blood lymphocytes were used as effector cells, virtually no cytolytic activity could be induced by DQ-33, whereas phytohemagglutinin-activated lymphocytes that had been expanded in vitro in IL-2-containing medium could be efficiently targeted against hepatoma cells. Targeting by DQ-33 bimAb was analyzed on different subsets of IL-2-cultured lymphocytes. It was evident that CD+4-8+ TCR alpha/beta+ and CD3+4-8-TCR gamma/delta+ lymphocytes were efficiently induced by bimAb to lyse human hepatoma cells, whereas no induction of cytolysis could be observed when CD3 + 4 + 8-TCR alpha/beta+ cells were used as effectors. DQ-33 bimAb was also able to induce lymphokine secretion (IL-2, GM-CSF and TNF-alpha) by all the different subsets of lymphocytes analyzed in the presence of target cells expressing the relevant antigen, independent of the expression of cytolytic activity.     

Ex vivo expansion of CD8+CD56+ and CD8+CD56- natural killer T cells specific for MUC1 mucin

Prostate cancers express MUC1, but nearly all metastatic cells lack HLA class I molecules. Thus, a lymphocyte population that can sense its antigenic environment, while also able to react to stimuli of natural killer (NK) cells, may be a more versatile effector cell population for antitumor immune responses. Herein, we report that tumor-specific MUC1 peptide, interleukin 2, and interleukin 12 act synergistically to stimulate the ex vivo expansion of CD8(+)CD56(-) T cells and CD8(+)CD56(+) natural killer T (NKT) cells from the peripheral blood mononuclear cells of prostate cancer patients, as well as healthy male and female donors. Both the CD56(+) NKT cells and CD56(-) T cells lysed allogeneic mucin-bearing target cells, as well as NK target cells, but not lymphokine-activated killer target cells. However, the CD56(+) NKT cells displayed a 2-fold greater cytolytic activity than the CD56(-) T cells. The mucin-specific cytolytic activity and NK cytolytic activities for both lymphocyte populations were independent of HLA class I and CD1 molecules. The CD56(-) T cells up-regulated CD56 with continued antigenic stimulation in the presence of interleukin 12, suggesting that CD8(+)CD56(-) T cells are NKT cells. However, CD56(+) NKT cells expand poorly to continued stimulation. All mucin-stimulated NKT cells exhibited the activated/memory CD45RO phenotype. The NKT cell lines express the alpha/beta T-cell receptor (TCR). The TCR repertoire was limited and varied with cell line, but was not the V alpha 24V beta 11 TCR typically associated with NKT cells. Whereas CD161 is generally considered a marker of NKT cells, the mucin-stimulated NKT cells did not express this marker. Thus, we have described two phenotypically distinct NKT types that do not display a biased TCR repertoire, but do display specificity for a tumor-specific peptide antigen (CTL-like activity), as well as HLA class I-deficient target cells (NK-like activity).     

Radiation leukemia virus-induced T-cell lymphomas with common T-cell receptor variable region structure and similar binding specificity for retrovirus

The 5C2 cell line was derived following culture of mouse spleen cells exposed in vivo and in vitro to radiation leukemia virus (RadLV) containing supernatants from the C6VL/1 T cell lymphoma. This cell line has been found to express an alpha beta T-cell receptor (TCR) identifiable with the Mab124-40 anti-clonotypic antibody which is specific for C6VL/1. It has been shown to be genetically and phenotypically distinct from C6VL/1 with a unique phenotype, i.e. CD4-, CD8-, CD3+, TCR-alpha beta. 5C2 has been shown to express high levels of alpha and beta chain mRNA and to utilize the same or similar V alpha and V beta region genes as C6VL/1. Whereas C6VL/1 binds cross-reactively to both RadLV/C6VL and an unrelated isolate RadLV/VL3, 5C2 has binding specificity for only RadLV/C6VL, which induced its proliferation. The anti-clonotypic antibody Mab124-40 specifically and completely inhibits binding of 5C2 to RadLV/C6VL at concentrations as low as 300 ng/ml. The 5C2 cell line can also be stimulated to increased proliferation by RadLV/C6VL. All of these data are consistent with the role of a TCR alpha beta heterodimer in binding and stimulation by RadLV and satisfy one prediction of the receptor-mediated leukemogenesis hypothesis that T-cell clones identifiable by their T-cell receptor clonotype may be targets for transformation by a particular retrovirus.     

Tumor-reactive CD8+ T-cell clones in patients after NY-ESO-1 peptide vaccination

A major objective of peptide vaccination is the induction of tumor-reactive CD8+ T-cells. We have shown that HLA-A2 positive cancer patients frequently develop an antigen-specific CD8+ T-cell response after vaccination with NY-ESO-1 peptides p157-165/p157-167. These T-cells are highly reactive with the peptides used for vaccination, but only rarely recognize HLA-matched, NY-ESO-1 expressing tumor cell lines. To address the apparent lack of tumor recognition of vaccine-induced CD8+ T-cell responses, we used autologous tumor cells for in vitro stimulation and expansion of pre- and postvaccine CD8+ T-cells. In contrast to standard presensitization methods with peptide-pulsed antigen-presenting cells, mixed lymphocyte tumor culture favored the selective expansion of low-frequency tumor-reactive T-cells. In four patients, we were able to demonstrate that antigen-specific and tumor-reactive T-cells are detectable and are indeed elicited as a result of NY-ESO-1 peptide vaccination. Further analyses of postvaccine antigen-specific T-cells at a clonal level show that vaccine-induced antigen-specific T-cells are heterogeneous in functional activity. These results suggest that the methods of immunomonitoring are critical to identify the proportion of tumor-reactive T-cells within the population of vaccine-induced antigen-specific effector cells. Our results show that immunization with NY-ESO-1 peptides leads to strong tumor-reactive CD8+ T-cell responses. Our findings suggest that approaches to peptide vaccination may be improved to induce higher numbers of antigen-specific T-cells and to selectively increase the proportion of CD8+ T-cells that have the capacity to recognize and eliminate tumor cells.     

Antigen spreading contributes to MAGE vaccination-induced regression of melanoma metastases

A core challenge in cancer immunotherapy is to understand the basis for efficacious vaccine responses in human patients. In previous work we identified a melanoma patient who displayed a low-level antivaccine cytolytic T-cell (CTL) response in blood with tumor regression after vaccination with melanoma antigens (MAGE). Using a genetic approach including T-cell receptor β (TCRβ) cDNA libraries, we found very few antivaccine CTLs in regressing metastases. However, a far greater number of TCRβ sequences were found with several of these corresponding to CTL clones specific for nonvaccine tumor antigens, suggesting that antigen spreading was occurring in regressing metastases. In this study, we found another TCR belonging to tumor-specific CTL enriched in regressing metastases and detectable in blood only after vaccination. We used the TCRβ sequence to detect and clone the desired T cells from tumor-infiltrating lymphocytes isolated from the patient. This CD8 clone specifically lysed autologous melanoma cells and displayed HLA-A2 restriction. Its target antigen was identified as the mitochondrial enzyme caseinolytic protease. The target antigen gene was mutated in the tumor, resulting in production of a neoantigen. Melanoma cell lysis by the CTL was increased by IFN-γ treatment due to preferential processing of the antigenic peptide by the immunoproteasome. These results argue that tumor rejection effectors in the patient were indeed CTL responding to nonvaccine tumor-specific antigens, further supporting our hypothesis. Among such antigens, the mutated antigen we found is the only antigen against which no T cells could be detected before vaccination. We propose that antigen spreading of an antitumor T-cell response to truly tumor-specific antigens contributes decisively to tumor regression.     

Expression of MHC class I and class I-like gene products on the cell membrane of mature and immature T cells

Beta 2-microglobulin (beta 2m) constitutes the 12 kD light chain of the MHC-encoded 43-kD glycoprotein HLA-ABC molecules, which are expressed on most nucleated cells. The T6 (CD1a) antigen is expressed on thymocytes in reciprocal manner to HLA-ABC, having a similar structure to the HLA-ABC molecule. We have determined the expression of beta 2m, HLA-ABC and the T6 antigen on the cell-surface of CD1a+ and CD1a- thymocytes (defined by NA1/34 expression), and have shown that despite immunophenotypic differences between these two stages of thymic maturation, the quantity of beta 2m-associated molecules expressed was not significantly different. The nature of the heavy (alpha) chain associated with beta 2m, however, differed since HLA-ABC had largely replaced T6 on the surface of CD1a- thymocytes. We also determined the expression of beta 2m and HLA-ABC on the surface of peripheral blood CD4+ and CD8+ T-cells, and showed that the CD8+ population expressed higher levels of these antigens than CD4+ T-cells, with no detectable excess beta 2m over HLA-ABC for either subpopulation. In addition, thymocytes expressed fewer beta 2m-associated determinants than peripheral blood T-cells. These results indicate an increase in the expression of beta 2m-associated molecules with differentiation from thymic to peripheral T-cell, with a further increase in such molecules expressed on the CD8+ compared to the CD4+ peripheral T-cell subpopulation.     

Reduced numbers of IL-7 receptor (CD127) expressing immune cells and IL-7-signaling defects in peripheral blood from patients with breast cancer

Interleukin-7-receptor-signaling plays a pivotal role in T-cell development and maintenance of T-cell memory. We studied IL-7Ralpha (CD127) expression in PBMCs obtained from patients with breast cancer and examined IL-7 receptor-mediated downstream effects defined by STAT5 phosphorylation (p-STAT5). Reduced numbers of IL-7Ralpha-positive cells were identified in CD4+ T-cells as well as in a CD8+ T-cell subset defined by CD8alpha/alpha homodimer expression in patients with breast cancer. PBMCs obtained from healthy donors (n = 19) and from patients with breast cancer (n = 19) exhibited constitutive p-STAT5 expression in the range of 0-6.4% in CD4+ T-cells and 0-4% in CD8+ T-cells. Stimulation with recombinant human IL-7 for 15 min increased p-STAT5 expression up to 36-97% in CD4+T-cells and to 26-90% in CD8+T-cells obtained from healthy control donors (n = 19). In contrast, PBMCs obtained from 13/19 patients with breast cancer did not respond to IL-7 as defined by STAT5 phosphorylation, despite expression of IL-7Ralpha on T-lymphocytes. T-cells were further characterized for IL- 2 and IFN-gamma production induced by PMA/Ionomycin. PBMCs from 9/19 patients with breast cancer showed decreased IL-2 and IFN-gamma production combined with IL-7-signaling defects; PBMCs from 4 patients with breast cancer exhibited deficient IL-7-signaling, yet intact cytokine production. Reduced numbers of IL-7Ralpha-positive cells and nonresponsiveness to IL-7, defined by lack of STAT5 phosphorylation, characterizes the immunological profile in T-cells from patients with breast cancer.     

Anti-4-1BB monoclonal antibody enhances rejection of large tumor burden by promoting survival but not clonal expansion of tumor-specific CD8+ T cells

Anti-4-1BB monoclonal antibody (mAb) has been shown to induce antitumor immunity by a CD4/CD8-dependent mechanism, but its direct effect on tumor-specific CD8+ T cells in tumor rejection is unclear. Here we used transgenic CD8+ T cells against the unmutated tumor rejection antigen P1A to analyze whether this mAb can promote CD8+ T-cell function against large tumors in the absence of CD4+ T-helper cells. RAG-2(-/-) mice were challenged with P1A-expressing plasmacytoma J558. Once tumor size reached a diameter of 0.85-1.75 cm, mice were treated with P1A-specific CD8+ CTL (P1CTL) in conjunction with anti-4-1BB mAb or control IgG. All of the mice showed a partial regression of tumor, but mice treated with anti-4-1BB mAb exhibited markedly enhanced tumor rejection, delayed tumor progression, and prolonged survival. Correspondingly, we observed a substantial increase in the number of P1CTL in anti-4-1BB mAb-treated mice. Surprisingly, anti-4-1BB mAb did not accelerate division of the tumor-specific CD8+ T cells, and the increase in tumor-specific T-cell number was due to reduced activation-induced cell death. These results indicate that anti-4-1BB mAb can promote CD8+ T cell-mediated protection against large tumors in the absence of CD4+ T-cell help by promoting P1CTL survival without increasing initial clonal expansion.     

Mechanisms involved in synergistic anticancer immunity of anti-4-1BB and anti-CD4 therapy

Anti-4-1BB-mediated anticancer effects were potentiated by depletion of CD4+ cells in B16F10 melanoma-bearing C57BL/6 mice. Anti-4-1BB induced the expansion and differentiation of polyclonal tumor-specific CD8+ T cells into IFN-gamma-producing CD11c+CD8+ T cells. The CD4+ cell depletion was responsible for facilitating immune cell infiltration into tumor tissues and removing some regulatory barriers such as T regulatory and indoleamine-2,3-dioxygenase (IDO)+ dendritic cells. Both monoclonal antibodies (mAb) contributed to the efficient induction of MHC class I molecules on the tumor cells in vivo. The effectors that mediated the anti-4-1BB effect were NKG2D+KLRG1+CD11c+CD8+ T cells that accumulated preferentially in the tumor tissues. Blocking NKG2D reduced the therapeutic effect by 20% to 26%, which may indicate that NKG2D contributes partially to tumor killing by the differentiated CD8+ T cells. Our results indicate that the combination of the two mAbs, agonistic anti-4-1BB and depleting anti-CD4, results in enhanced production of efficient tumor-killing CTLs, facilitation of their infiltration, and production of a susceptible tumor microenvironment.     

TCRgammadelta+ large granular lymphocyte leukemias reflect the spectrum of normal antigen-selected TCRgammadelta+ T-cells.

T-cell large granular lymphocytes (LGL) proliferations range from reactive expansions of activated T cells to T-cell leukemias and show variable clinical presentation and disease course. The vast majority of T-LGL proliferations express TCRalphabeta. Much less is known about the characteristics and pathogenesis of TCRgammadelta+ cases. We evaluated 44 patients with clonal TCRgammadelta+ T-LGL proliferations with respect to clinical data, immunophenotype and TCR gene rearrangement pattern. TCRgammadelta+ T-LGL leukemia patients had similar clinical presentations as TCRalphabeta+ T-LGL leukemia patients. Their course was indolent and 61% of patients were symptomatic. The most common clinical manifestations were chronic cytopenias - neutropenia (48%), anemia (23%), thrombocytopenia (9%), pancytopenia (2%) - and to a lesser extent splenomegaly (18%). Also multiple associated autoimmune (34%) and hematological (14%) disorders were found. Leukemic LGLs were predominantly positive for CD2, CD5, CD7, CD8, and CD57, whereas variable expression was seen for CD16, CD56, CD11b, and CD11c. The Vgamma9/Vdelta2 immunophenotype was found in 48% of cases and 43% of cases was positive for Vdelta1, reflecting the TCR-spectrum of normal TCRgammadelta+ T-cells in adult PB. Identification of the well-defined post-thymic Vdelta2-Jdelta1 selection determinant in all evaluable Vgamma9+/Vdelta2+ patients, is suggestive of common (super)antigen involvement in the pathogenesis of these TCRgammadelta+ T-LGL leukemia patients.