In situ sensory adaptation of tumor-infiltrating T lymphocytes to peptide-MHC levels elicits strong antitumor reactivity

We have isolated from tumor-infiltrating lymphocytes (TIL) and PBL of a lung carcinoma patient several tumor-specific T cell clones displaying similar peptide-MHC tetramer staining and expressing a unique TCR. Although these clones elicited identical functional avidity and similar cytolytic potential, only T cell clones derived from TIL efficiently lysed autologous tumor cells. Interestingly, all of these clones expressed the same T cell surface markers except for the TCR inhibitory molecule CD5, which was expressed at much lower levels in TIL than in PBL. Video-imaging recordings demonstrated that, although both T cell clones could form stable conjugates with tumor cells, the Ca(2+) response occurred in TIL clones only. Significantly, analysis of a panel of circulating clones indicated that antitumor cytolytic activity was inversely proportional to CD5 expression levels. Importantly, CD5 levels in TIL appeared to parallel the signaling intensity of the TCR/peptide-MHC interaction. Thus, in situ regulation of CD5 expression may be a strategy used by CTL to adapt their sensitivity to intratumoral peptide-MHC levels.     

T lymphocytes can mediate lysis of autologous melanoma cells by multiple mechanisms: Evidence with a single T cell clone

Summary The specificity analysis of a CD3⁺, WT31⁺, CD8⁺ cytotoxic T lymphocyte (CTL) clone (CTL 49), isolated from peripheral blood lymphocytes of a melanoma patient (no. 665) after mixed lymphocyte culture with an HLA-A2⁺ allogeneic lymphoblastoid cell line (VSKB-LCL), revealed that CTL 49 could lyse, in addition to HLA-A2⁺ lines, autologous HLA-A2^– melanoma (Me665/2) and K562 targets. Killing of VSKB-LCL, but not of Me665/2, could be inhibited by anti-CD3 and by anti-HLA-A2 antibodies or by modulation of the CD3 complex. Cold-target competition studies showed that K562, but not VSKB-LCL, could compete with Me665/2 for lysis by CTL 49. However, unlike K562, Me665/2 could be lysed by CTL 49 in a Ca²⁺-independent fashion in 4 h and 18 h assays. CTL 49 expressed mRNA specific for tumor necrosis factor (TNF) and, to a lesser extent, for lymphotoxin (TNF). Exposure of the clone to anti-CD3 antibodies induced the expression of interferon(IFN)--specific and the up-regulation of TNF- and TNF-specific mRNA. Antibodies to TNF, TNF and IFN reduced the lysis of Me665/2, but not of K562, by CTL 49 in 18-h cytotoxic assays. Antibodies to TNF and to IFN almost completely inhibited the lysis seen on Me665/2 (but not on K562), in 96-h assays, by supernatants isolated from VSKB-LCL- or anti-CD3-stimulated CTL 49 cells. Taken together, these data indicate that major-histocompatibility-complex-independent lysis of autologous tumor cells and of natural killer reference targets by the same alloreactive T cell clone are activities related at the level of target recognition but distinct at the level of the lytic hit. Thus, efficient lysis of autologous tumor cells results from a complex mechanism based upon direct effector-target interaction as well as on cytokine-mediated cytolytic effects.     

Cloned human cytotoxic T lymphocyte (CTL) lines reactive with autologous melanoma cells. I. In vitro generation, isolation, and analysis to phenotype and specificity

Activation of peripheral blood lymphocytes (PBL) from a melanoma patient either in secondary MLC in which EBV-transformed B cells from the cell line JY were used as stimulator cells, or by co-cultivation with the autologous melanoma cells in a mixed leukocyte tumor cell culture (MLTC) resulted in the generation of cytotoxic activity against the autologous melanoma (O-mel) cells. From these activated bulk cultures four cloned cytotoxic T lymphocyte (CTL) lines were isolated. The CTL clone O-1 (T3+, T4+, T8-, OKM-1-, HNK-, and HLA-DR+), and O-36 (T3+, T4-, T8+, OKM-, HNK-, and HLA-DR+) were obtained from MLC, whereas the CTLC clones O-C7 (T3+, T4+, T8-, OKM-1-, HNK-, and HLA-DR+) and O-D5 (T3+, T4-, T8+, OKM-1-, HNK, and HLA-DR+) were isolated from autologous MLTC. All four CTL clones were strongly cytotoxic for O-mel cells but failed to lyse autologous fibroblasts and autologous T lymphoblasts. Moreover, the CTL clones lacked NK activity as measured against K562 and Daudi cells. Panel studies indicated that the CTL clones also killed approximately 50% of the allogeneic melanoma cells preferentially, whereas the corresponding T lymphoblasts were not lysed. Monoclonal antibodies against class I (W6/32) and class II (279) MHC antigens failed to block the reactivity of the CTL clones against O-mel and allogeneic melanoma cells, indicating that a proportion of human melanoma cells share determinants that are different from HLA antigens and that are recognized by CTL clones. In contrast to the CTL clones isolated from MLTC, the clones obtained from MLC also lysed JY cells, which initially were used as stimulator cells. The reactivity of O-36 against JY could be inhibited with W6/32, demonstrating that this reactivity was directed against class I MHC antigens. These results suggest that the lysis of O-mel and JY cells by O-36 has to be attributed to two independent specificities of this CTL clone. The specificity of the other cross-reactive CTL clone (O-1) could not be determined. The notion that individual CTL clones can have two specificities was supported by the following observations. The cytotoxic reactivity of both O-1 (T4+) and O-36 (T8+) against JY was blocked by monoclonal antibodies directed against T3 and human LFA-1, and against T3, T8, and human LFA-1, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)     

Human cytotoxic T cell clones directed against herpes simplex virus-infected cells. I. Lysis restricted by HLA class II MB and DR antigens

In contrast to general findings that mouse and human cytotoxic T lymphocytes (CTL) are restricted in cytotoxic activity by major histocompatibility complex (MHC) class I antigens, we previously found that some herpes simplex virus (HSV) type I-infected cells that shared no HLA class I antigens with the HSV-1-stimulated lymphocytes were lysed. In this study, we addressed the question of the role of HLA antigens in human T cell-mediated lysis of HSV-1-infected cells by generating clones of HSV-1-directed CTL from two HSV-1-seropositive individuals. CTL clones that lysed autologous HSV-1-infected lymphoblastoid cell lines (LCL), but not natural killer-sensitive K562 cells or uninfected or influenza virus-infected LCL, were tested for cytotoxicity against a panel of allogeneic HSV-1-infected LCL. Clone KL-35 from individual KL lysed only HSV-1-infected LCL sharing the HLA class II MB1 antigen with KL. With all four CTL clones isolated from individual PM, only HSV-1-infected LCL sharing DR1 with PM were lysed. Monoclonal antibody s3/4 (directed against MB1 ), but not TS1/16 or B33 .1 (directed against a DR framework determinant), blocked lysis of autologous HSV-1-infected cells by KL-35. In contrast, B33 .1, but not s3/4, blocked lysis of autologous HSV-1-infected cells by the PM CTL clones but not by KL-35. Together, these results indicate that our five human CTL clones which are directed against HSV-1-infected cells, and which are all OKT3+, OKT4+, OKT8-, are restricted in lytic activity by HLA class II MB and DR antigens. These results suggest that the HLA D region-encoded class II antigens may be important in the recognition and destruction of virus-infected cells by human CTL.     

Alloantigen-induced cytotoxicity against syngeneic tumor cells: analysis at the clonal level

It has been shown that peritoneal exudate cells (PEC) from BALB/c mice immunized with minor histocompatibility antigens presented by DBA/2 or B10.D2 spleen cells are capable of lysing syngeneic YC8 tumor cells in a 4-hr 51Cr-release assay. In this study, we employed limiting dilution analysis to determine the frequency of CTL precursors (CTL-P) reactive against both the specific DBA/2 (or P815) target and the syngeneic tumor YC8. The mean frequency of anti-DBA/2 CTL-P in PEC from BALB/c mice immunized with DBA/2 was 1/302. Between one-third and one-fifth of limiting dilution microcultures that exhibited lytic activity against DBA/2 lymphoblasts (or P815) were also able to lyse YC8. No lysis of YC8 was observed in the absence of a parallel lysis on DBA/2 lymphoblasts or P815 target cells. T cell clones, derived by micromanipulation from microcultures selected for cytotoxic activity against YC8 and/or P815, maintained either the specific anti-allogeneic or the doubly reactive ( antiallogeneic plus anti-syngeneic tumor) phenotype. Fourteen clones (six specific and eight doubly reactive) were tested for cytotoxic activity on a panel of target cells with different haplotypes. All showed H-2-restricted specificity for minor histocompatibility antigens shared by DBA/2 and B10.D2. The restriction element for some of the clones mapped in the K region of the H-2 complex, whereas for other clones the restriction element mapped in the D region; both K- and D-restricted clones were able to lyse YC8. When the clones that exhibited lysis on YC8 were tested on two other BALB/c tumor targets, LSTRA, a Moloney virus induced lymphoma, and RL male-1, a radiation induced lymphoma, two of seven were found to lyse all three syngeneic tumor targets equally well, but not syngeneic BALB/c blasts. These clones were functionally categorized as conventional CTL because they were unable to proliferate when cultured with antigen in the absence of exogenous lymphokines, and were unable to produce lymphokine with IL 2 activity when stimulated by the appropriate splenocytes. When tested in vivo in a Winn assay, a strong anti-tumor activity against YC8 was exerted by the anti-DBA/2 clones DY4 -3 and DY16 -3. These clones lysed both YC8 and the immunizing target cells in vitro. No in vivo effect in neutralizing YC8 tumor growth was observed with clone D2-1, a clone that lysed DBA/2 targets but not YC8 in vitro.     

Lysis of fresh human solid tumor cells by autologous lymphocytes activated in vitro by allosensitization

Summary We have previously demonstrated that cancer patients' peripheral blood lymphocytes (PBL) allosensitized against single or pool normal donor PBL are capable of lysing fresh autologous tumor cells in a 4-h ⁵¹Cr-release assay. In this report, we present further investigations into this phenomenon. These alloactivated killer cells (A-AK cells) lysed autologous and allogeneic tumors and allogeneic but not autologous PBL. Furthermore, cold target inhibition studies demonstrated that autologous and allogeneic tumors were lysed by the same effector cells. Multiple metastases from the same patient were equivalently lysed by these A-AK cells. The presence of adherent cells and proliferation of the precursors were necessary to generate A-AK cells, although the effector cell itself was radioresistant and nonadherent. The effects of allosensitization were enhanced by the addition of lectin-free interleukin-2 preparations to the in vitro culture by partial depletion of adherent cells prior to sensitization. The A-AK effector cell was OKT3+, OKT8+, OKT4–, OKM1– and could be generated by just 3 days of allosensitization. The precursors for A-AK cells could be separated from NK cells on percoll gradients and lysis could be generated from thoracic duct lymphocytes, a population devoid of NK cells. The phenotype of the majority of the precursor cells was OKT3+, OKT4–. These allocatived PBL could be expanded in crude or lectin-free interleukin-2 without loss of cytotoxicity for fresh autologous tumor cells. Activated T cells represent a population of non-NK cells with broad lytic specificity for fresh tumor cells. Such cells may be of value in the adoptive immunotherapy of human solid tumors and may play a role in immune surveillance.     

Characterization of the CD4+ and CD8+ tumor infiltrating lymphocytes propagated with bispecific monoclonal antibodies

To study the CD4+ and CD8+ tumor infiltrating lymphocytes (TIL) in the antitumor response, we propagated these subsets directly from tumor tissues with anti-CD3:anti-CD8 (CD3,8) and anti-CD3:anti-CD4 (CD3,4) bispecific mAb (BSMAB). CD3,8 BSMAB cause selective cytolysis of CD8+ lymphocytes by bridging the CD8 molecules of target lymphocytes to the CD3 molecular complex of cytolytic T lymphocytes with concurrent activation and proliferation of residual CD3+CD4+ T lymphocytes. Similarly, CD3,4 BSMAB cause selective lysis of CD4+ lymphocytes whereas concurrently activating the residual CD3+CD8+ T cells. Small tumor fragments from four malignant melanoma and three renal cell carcinoma patients were cultured in medium containing CD3,8 + IL-2, CD3,4 + IL-2, or IL-2 alone. CD3,8 led to selective propagation of the CD4+ TIL whereas CD3,4 led to selective propagation of the CD8+ TIL from each of the tumors. The phenotypes of the TIL subset cultures were generally stable when assayed over a 1 to 3 months period and after further expansion with anti-CD3 mAb or lectins. Specific 51Cr release of labeled target cells that were bridged to the CD3 molecular complexes of TIL suggested that both CD4+ and CD8+ TIL cultures have the capacity of mediating cytolysis via their Ti/CD3 TCR complexes. In addition, both CD4+ and CD8+ TIL cultures from most patients caused substantial (greater than 20%) lysis of the NK-sensitive K562 cell line. The majority of CD4+ but not CD8+ TIL cultures also produced substantial lysis of the NK-resistant Daudi cell line. Lysis of the autologous tumor by the TIL subsets was assessed in two patients with malignant melanoma. The CD8+ TIL from one tumor demonstrated cytotoxic activity against the autologous tumor but negligible lysis of allogeneic melanoma targets. In conclusion, immunocompetent CD4+ and CD8+ TIL subsets can be isolated and expanded directly from small tumor fragments of malignant melanoma and renal cell carcinoma using BSMAB. The resultant TIL subsets can be further expanded for detailed studies or for adoptive immunotherapy.     

Functional properties of tumor-infiltrating and blood lymphocytes in patients with solid tumors: effects of tumor cells and their supernatants on proliferative responses of lymphocytes

Tumor-infiltrating lymphocytes (TIL) were obtained from 22 humans with solid tumors. In three cases only, one colon and two lung carcinomas, TIL which contained from 3 to 10% of T cells expressing the interleukin 2 receptor (IL 2R) were obtained, and these proliferated in the presence of exogenous IL 2. In most TIL preparations, however, the T lymphocytes did not express the IL 2R and failed to proliferate in response to IL 2. In contrast, TIL were able to proliferate in response to irradiated allogeneic spleen cells in mixed lymphocyte culture. Proliferative responses of autologous PBL were not inhibited by the addition of TIL. In most tumors, the TIL showed no response or had significantly lower (p less than 0.01) responses to PHA, Con A, and the phorbol ester TPA than did autologous peripheral blood lymphocytes (PBL). A limiting-dilution microculture system which allows clonal growth of every T cell was used to demonstrate decreased responses of the TIL to PHA at a single-cell level. In contrast to normal PBL-T with proliferating frequencies from 0.46 to 1.0, those for T cells in three TIL preparations were zero, 0.005, and 0.01. Normal PBL exposed in vitro to tumor cells or their supernatants lost the ability to respond to mitogens and to clone normally (e.g., proliferating frequency of 0.147 vs 0.863 in control). The TIL isolated from solid tumors resemble normal PBL exposed in vitro to tumor cells or their supernatants in terms of decreased responses to mitogens and poor clonogenicity in the PHA-dependent microculture system. It is possible that tumor cells may inhibit certain functions of the TIL in human solid tumors.     

Tumor-infiltrating CD4+ T lymphocytes express APO2 ligand (APO2L)/TRAIL upon specific stimulation with autologous lung carcinoma cells: role of IFN-alpha on APO2L/TRAIL expression and -mediated cytotoxicity

In the present report, we have investigated TRAIL/APO2 ligand (APO2L) expression, regulation, and function in human lung carcinoma tumor-infiltrating lymphocytes. Using a panel of non-small cell lung carcinoma cell lines, we first showed that most of them expressed TRAIL-R1/DR4, TRAIL-R2/DR5, but not TRAIL-R3/DcR1 and TRAIL-R4/DcR2, and were susceptible to APO2L/TRAIL-induced cell death. Two APO2L/TRAIL-sensitive tumor cell lines (MHC class I(+)/II(+) or I(+)/II(-)) were selected and specific CD4(+) HLA-DR- or CD8(+) HLA-A2-restricted CTL clones were respectively isolated from autologous tumor-infiltrating lymphocytes. Interestingly, although the established T cell clones did not constitutively express detectable levels of APO2L/TRAIL, engagement of their TCR via activation with specific tumor cells selectively induced profound APO2L/TRAIL expression on the CD4(+), but not on the CD8(+), CTL clones. Furthermore, as opposed to the CD8(+) CTL clone which mainly used granule exocytosis pathway, the CD4(+) CTL clone lysed the specific target via both perforin/granzymes and APO2L/TRAIL-mediated mechanisms. The latter cytotoxicity correlated with APO2L/TRAIL expression and was significantly enhanced in the presence of IFN-alpha. More interestingly, in vivo studies performed in SCID/nonobese diabetic mice transplanted with autologous tumor and transferred with the specific CD4(+) CTL clone in combination with IFN-alpha resulted in an important APO2L/TRAIL-mediated tumor growth inhibition, which was prohibited by soluble TRAIL-R2. Our findings suggest that APO2L/TRAIL, specifically induced by autologous tumor and up-regulated by IFN-alpha, may be a key mediator of tumor-specific CD4(+) CTL-mediated cell death and point to a potent role of this T cell subset in tumor growth control.     

Lymphocytes infiltrating human ovarian tumors. I. Role of Leu-19 (NKH1)-positive recombinant IL-2-activated cultures of lymphocytes infiltrating human ovarian tumors

Tumor-infiltrating lymphocytes (TIL) were obtained from human ovarian tumors, expanded in the presence of IL-2 in culture and studied for cytotoxicity against fresh autologous and allogeneic ovarian carcinoma (CA) targets. TIL from ovarian tumors grew well in long term cultures, achieving from 8- to 682-fold expansion. TIL cultured with IL-2 were cytotoxic against both autologous and allogeneic fresh ovarian CA targets, and no specificity for autologous tumor could be demonstrated in any of the cultures. In all fresh TIL preparations, CD3+ lymphocytes were the major cell type and contained a high proportion (up to 51%) of activated (IL-2R+) cells as determined by two-color flow cytometry. Sorting of bulk TIL cultures followed by cytotoxicity assays identified the Leu-19+ cells, both CD3+ and CD3-, as effectors of cytotoxicity against autologous and allogeneic tumor cell targets. Cold target inhibition assays showed that allogeneic targets (both ovarian CA and a sarcoma) competed effectively with autologous ovarian CA targets for Leu-19+ effectors in TIL cultures. mAb to Leu-19 or Leu-2a did not block lysis of autologous targets by sorted effectors. OKT3 antibody augmented lysis of autologous targets by CD3+Leu-19- effectors only. These results show that non-MHC-restricted Leu-19+ effectors in cultures of TIL with 1000 U/ml of rIL-2 mediate lysis of autologous and allogeneic tumor cells. The CD3+Leu-19- cells, the main population in these cultures, do not mediate tumor lysis. To determine the phenotype of antitumor effectors in IL-2 cultures of TIL, cell sorting followed by functional assays are necessary.     

Cellular immune response to human sarcomas: cytotoxic T cell clones reactive with autologous sarcomas. I. Development, phenotype, and specificity

Human T cell clones cytotoxic for autologous sarcoma cell lines have been developed from patient JM with an osteogenic sarcoma, and from patients EG and RM with malignant fibrohistiocytoma. These clones were derived from the cocultivation of peripheral blood lymphocytes (PBL) with the respective patient's autologous irradiated established tumor cell lines (AIT). After two cycles of stimulation for 5 days in bulk culture, these "educated" lymphocytes were seeded at a density of 1 X 10(6) cells/well in 24-well plates and were cultured in the presence of highly purified natural IL 2 and AIT, the latter serving as a feeder layer. Cell numbers were reduced from the initial seeding density by one log each week until reaching a density of 10(2) cells. These cells were found to be stable in viability and cytotoxic activity, after which limiting dilution was then performed. Within 4 to 6 wk, clones were isolated with unique specificities. These clones were capable of proliferating to a total density of 10(9) cells/ml and maintained their specific cytotoxicity for more than 6 mo. Testing with a panel of target cells of various histotypes, cold-target inhibition assays, and blocking of cytotoxicity with anti-HLA monoclonal antibodies showed that the T cell clones recognize a common sarcoma-associated antigen and that the lysis is HLA restricted. Phenotypically, cytotoxic clones derived from JM were Leu-1+, Leu-2+, and Leu-3-, whereas those derived from EG exhibited either Leu-24 or Leu-3+ markers, the latter phenotype lacking cytotoxicity. RM exhibited mainly Leu-3+ clones with strong cytotoxicity. All were HNK-1- and HLA class II+, with less than 1% of cells of each clone stained by anti-TAC monoclonal antibody. The clones from each patient did not lyse autologous or allogeneic PBL, mitogen-induced T lymphoblasts, normal fibroblasts, cells isolated from benign neoplasms, carcinoma cells, Daudi B lymphoid cells, or K562 cells. With the exception of EG, all clones produced immune interferon in a range from 12 to 50 U/ml. The generation of long-term specific T cell clones can be used to further dissect the cellular immune response to sarcomas. Cytotoxic T cell clones have potential application for tumor immunotherapy.     

Recognition of neuroectodermal tumors by melanoma-specific cytotoxic T lymphocytes: evidence for antigen sharing by tumors derived from the neural crest

Melanomas from different patients have been shown to express shared tumor antigens, which can be recognized in the context of the appropriate MHC class 1 molecules by cytolytic T cells. To determine if T-cell-defined melanoma antigens are expressed on other tumors of neuroectodermal origin, four melanoma-specific cytotoxic T lymphocyte (CTL) cultures derived from tumor-infiltrating lymphocytes (TIL) were tested for lysis of a panel of 23 HLA-A2⁺ neuroectodermal tumor cell lines of various histologies, including retinoblastoma (1), neuroblastoma (8), neuroepithelioma (6), astrocytoma (2), neuroglioma (1), and Ewing's sarcoma (5). Low expression of MHC class I and/or ICAM-1 molecules was found on 22 of 23 neuroectodermal tumor lines, and could be enhanced by treatment with interferon (IFN). Following IFN treatment, three Ewing's sarcoma lines were lysed by at least one melanoma TIL culture, and levels of lysis were comparable to melanoma lysis by these TIL. Lysis could be inhibited by monoclonal antibodies directed against MHC class I molecules and against CD3, indicating specific immune recognition of tumor-associated antigens. None of the other neuroectodermal tumors tested were lysed by TIL, but they could be lysed by non-MHC-restricted lymphokine-activated killer cells. This demonstration of immunological cross-reactivity between melanomas and Ewing's sarcomas, two tumors of distinct histological types with a common embryonic origin, has implications for the developmental nature of these CTL-defined tumor antigens. It also raises the possibility that specific antitumor immunotherapies, such as vaccines, may be reactive against more than one form of cancer.     

Tumour-infiltrating lymphocytes mediate lysis of autologous squamous cell carcinomas of the head and neck

Tumour-infiltrating lymphocytes (TIL) and tumours from six patients with squamous cell carcinomas of the head and neck (SCCHN) were investigated. The six tumours all expressed major histocompatibility complex (MHC) class I antigens both in vivo and as tumor cell lines grown in vitro. In addition, the cancer cells either overexpressed the tumour-suppressor gene product p53 or harboured human papilloma virus 16/18 (HPV). The TIL were expanded in vitro in the presence of interleukin-2, immobilised anti-CD3 mAb and soluble anti-CD28 mAb. Expanded TIL cultures contained both CD4+and CD8+T cells, but generally contained few CD56+CD3-cells of the natural killer (NK) phenotype. CD8+T cells dominated the individual TIL cultures from five of the six patients and showed significant autologous tumour cell lysis. In TIL cultures derived from four of these tumour-reactive TIL cultures, killing could be partially blocked by an anti-MHC class I mAb. TIL cultures reacting with autologous tumour cells also showed strong TCR/CD3-redirected cytotoxicity when assayed against hybridoma cells expressing anti-TCR/CD3 mAb as well as natural-killer(NK)-like activity. A number of TIL cultures devoid of autologous tumour cell lysis were capable of lysing the natural-killer(NK)-sensitive K562 cell line suggesting that the SCCHN cells themselves are resistant to NK-like lysis. In conclusion, TIL cultures from head and neck carcinomas contain T cells which, upon expansion in vitro, can lyse autologous tumour cells in a MHC-class-I-restricted fashion. Thus, the results of the present study document that carcinomas of the head and neck in some patients are infiltrated by cytotoxic T cell precursors potentially capable of rejecting the autologous tumour.     

Enhancement of in vitro tumor-infiltrating lymphocyte cytotoxicity by heteroconjugated antibodies.

Tumor-infiltrating lymphocytes (TIL) were obtained from a mouse melanoma cell line (CL 62) transfected with the gene for the human melanoma Ag p97. TIL were cultured with anti-CD3 antibody and IL-2 for up to 38 days. Flow cytometry identified these TIL as Thy-1.2 + ve/CD4-ve/CD8 + ve cells. A heteroconjugated antibody 500A2 x 96.5, specific for both the CD3 Ag on TIL and the p97 Ag on CL 62 melanoma cells, was prepared using N-succinimidyl-3-(2-pyridyldithio)-propionate as a linking agent. TIL alone demonstrated low levels of cytotoxicity against autologous CL 62 tumor and also against the parental K1735 tumor and an allogeneic murine melanoma (B16). The addition of 500A2 x 96.5 heteroconjugated antibody enhanced TIL-mediated lysis of CL 62 tumor, but not of the K1735 or B16 tumors. This enhanced cytotoxicity was elicited at E:T ratios as low as 0.4:1, and in TIL cultured for 7 to 38 days. These results suggest that hetero-conjugated antibody may enhance the anti-tumor effect of TIL in vivo.     

Dendritic cells infected with a vaccinia vector carrying the human gp100 gene simultaneously present multiple specificities and elicit high-affinity T cells reactive to multiple epitopes and restricted by HLA-A2 and -A3

To investigate the ability of human dendritic cells (DC) to process and present multiple epitopes from the gp100 melanoma tumor-associated Ags (TAA), DC from melanoma patients expressing HLA-A2 and HLA-A3 were pulsed with gp100-derived peptides G9154, G9209, or G9280 or were infected with a vaccinia vector (Vac-Pmel/gp100) containing the gene for gp100 and used to elicit CTL from autologous PBL. CTL were also generated after stimulation of PBL with autologous tumor. CTL induced with autologous tumor stimulation demonstrated HLA-A2-restricted, gp100-specific lysis of autologous and allogeneic tumors and no lysis of HLA-A3-expressing, gp100+ target cells. CTL generated by G9154, G9209, or G9280 peptide-pulsed, DC-lysed, HLA-A2-matched EBV transformed B cells pulsed with the corresponding peptide. CTL generated by Vac-Pmel/gp100-infected DC (DC/Pmel) lysed HLA-A2- or HLA-A3-matched B cell lines pulsed with the HLA-A2-restricted G9154, G9209, or G9280 or with the HLA-A3-restricted G917 peptide derived from gp100. Furthermore, these DC/Pmel-induced CTL demonstrated potent cytotoxicity against allogeneic HLA-A2- or HLA-A3-matched gp100+ melanoma cells and autologous tumor. We conclude that DC-expressing TAA present multiple gp100 epitopes in the context of multiple HLA class I-restricting alleles and elicit CTL that recognize multiple gp100-derived peptides in the context of multiple HLA class I alleles. The data suggest that for tumor immunotherapy, genetically modified DC that express an entire TAA may present the full array of possible CTL epitopes in the context of all possible HLA alleles and may be superior to DC pulsed with limited numbers of defined peptides.     

The human lymphokine-activated killer cell system. V. Purified recombinant interleukin 2 activates cytotoxic lymphocytes which lyse both natural killer-resistant autologous and allogeneic tumors and trinitrophenyl-modified autologous peripheral blood lymphocytes

Culture of human peripheral blood lymphocytes (PBL) in purified natural or recombinant interleukin 2 in the absence of exogenous antigen or mitogen causes the differentiation of nonlytic precursor cells into lymphokine-activated killers (LAK). A titration of purified Jurkat IL-2 (BRMP, FCRC, NIH) IL-2 showed that the relatively low concentration of 5 U/ml was optimal for LAK activation. When the responding PBL were pretreated with either mitomycin C or gamma irradiation, LAK activation did not occur, indicating that proliferation, in addition to differentiation, is required. The spectrum of target cells susceptible to LAK lysis in a 4-hr chromium-51-release assay includes fresh NK-resistant tumor cells and trinitrophenyl (TNP)-modified autologous PBL. Unmodified PBL are not lysed. Cold target inhibition studies indicated that LAK lysis of autologous TNP-PBL is totally inhibited by fresh tumors cells, and that tumor lysis is inhibited by TNP-PBL. Additionally, allogeneic tumors totally inhibit lysis of autologous tumor cells in other cold target studies. These results demonstrate that the lytic activity expressed by LAK is not HLA restricted, is not limited to tumor cells, and is "polyspecific" as indicated by the cross-reactive recognition of multiple target cell types in these cold target inhibition studies.     

Cytokines alter target cell susceptibility to lysis. II. Evaluation of tumor infiltrating lymphocytes

We studied the susceptibility of autologous and allogeneic tumors to lysis by human tumor infiltrating lymphocytes (TIL) after pre-incubation of the tumors with human rIFN-gamma and human rTNF-alpha. Preincubation of the tumor lines with IFN-gamma or TNF enhanced susceptibility to lysis significantly; the combination of both cytokines was more effective than either alone. Pretreatment for at least 24 h was required to enhance lytic susceptibility and maximal lysis was observed after pretreatment for 48 to 72 h. Highly specific TIL lysed only their autologous tumor targets and failed to lyse cytokine pretreated allogeneic tumor cells. In TIL populations with varying specificity, cytokine pretreatment of targets enhanced autologous lysis as well as allogeneic lysis. This cytokine-mediated effect could also be observed in a lectin-dependent cytotoxicity assay and did not correlate directly with enhanced expression of MHC class I Ag or the adhesion molecules LFA-3 and ICAM-1. These results suggest that enhancement of lysis may occur at a postbinding stage by making the target cell more sensitive to the cytotoxic factors delivered by the killer cell. The fact that lysis of cytokine treated targets by cells with LAK activity was not enhanced suggests that cells with lymphokine-activated killer activity and tumor-derived T cells kill tumor targets via different mechanisms.     

Semiquantitative analysis of Th1 and Th2 cytokine expression in CD3+, CD4+, and CD8+renal-cell-carcinoma-infiltrating lymphocytes

The mRNA expression of Th1 and Th2 cytokines was compared in freshly isolated CD3⁺ tumor-infiltrating lymphocytes (CD3⁺ TIL) and in autologous CD3⁺ peripheral blood lymphocytes (CD3⁺ PBL) obtained simultaneously from 20 patients with renal cell carcinomas (RCC). In addition cytokine expression was compared in CD4⁺ TIL and CD8⁺ TIL from another group of 20 patients with RCC. TIL were isolated from mechanically disaggregated tumor material and PBL from peripheral blood by gradient centrifugation and subsequent selection with anti-CD3, anti-CD4 or anti-CD8 magnetic beads. In these pure lymphocyte preparations the constitutive expression of interleukin-1 (IL-1), IL-2, IL-10, interferon γ (IFN), and tumor necrosis factor α (TNF) was determined by using a polymerase-chain-reaction-assisted mRNA amplification assay. In the CD3⁺ TIL, levels of mRNA for IFN, IL-10, IL-1 and TNF were significantly higher than in the autologous CD3⁺ PBL whereas IL-2 expression was rather low and did not differ in the two populations. Comparison of cytokine mRNA expression in CD4⁺ TIL and simultaneously obtained CD8⁺ TIL revealed a significantly higher expression of IFN in the CD8⁺ cells. These data reflect an in vivo activation of RCC-infiltrating lymphocytes at the mRNA level with respect to the Th1 as well as the Th2 immune response. Th1 activation seems to be most evident in the CD8⁺ TIL. Received: 14 January 1999 / Accepted: 30 April 1999