Orally administered streptococcal preparation,OK-432 augments the antitumor immunity of patients with gastric or colorectal cancer

A streptococcal preparation, OK-432, was orally administered at a dose of 5 KE to patients with gastric or colorectal cancer for 7–14 days before their operations, and its immunomodulatory effects on peripheral blood lymphocytes (PBL), regional node lymphocytes (RNL) and tumor infiltrating lymphocytes (TIL) were assessed. The group treated with OK-432 included 8 gastric and 6 colorectal cancer patients, and the control group included 8 gastric and 8 colorectal cancer patients. The NK cell activity of PBL was significantly augmented by the oral administration of OK-432, and the proportions of Leu 7+ and Leu 11+ cells in PBL also increased. The responses of PBL and TIL to autologous tumor extracts in the presence of interleukin-2 were enhanced after the oral administration of OK-432. The proportion of OKT8+ cells in PBL increased after treatment with oral OK-432, whereas the proportion in RNL significantly decreased. These results indicate that oral OK-432 affects NK and T cells and may augment the antitumor immunity of patients with gastrointestinal cancer.     

Human papillomavirus type 16 E7 peptide-directed CD8+ T cells from patients with cervical cancer are cross-reactive with the coronavirus NS2 protein

Human papillomavirus type 16 (HPV16) E6 and E7 oncoproteins are required for cellular transformation and represent candidate targets for HPV-specific and major histocompatibility complex class I-restricted CD8(+)-T-cell responses in patients with cervical cancer. Recent evidence suggests that cross-reactivity represents the inherent nature of the T-cell repertoire. We identified HLA-A2 binding HPV16 E7 variant peptides from human, bacterial, or viral origin which are able to drive CD8(+)-T-cell responses directed against wild-type HPV16 E7 amino acid 11 to 19/20 (E7(11-19/20)) epitope YMLDLQPET(T) in vitro. CD8(+) T cells reacting to the HLA-A2-presented peptide from HPV16 E7(11-19(20)) recognized also the HLA-A2 binding peptide TMLDIQPED (amino acids 52 to 60) from the human coronavirus OC43 NS2 gene product. Establishment of coronavirus NS2-specific, HLA-A2-restricted CD8(+)-T-cell clones and ex vivo analysis of HPV16 E7 specific T cells obtained by HLA-A2 tetramer-guided sorting from PBL or tumor-infiltrating lymphocytes obtained from patients with cervical cancer showed that cross-reactivity with HPV16 E7(11-19(20)) and coronavirus NS2(52-60) represents a common feature of this antiviral immune response defined by cytokine production. Zero of 10 patients with carcinoma in situ neoplasia and 3 of 18 patients with cervical cancer showed > or =0.1% HPV16 E7-reactive T cells in CD8(+) peripheral blood lymphocytes. In vivo priming with HPV16 was confirmed in patients with cervical cancer or preinvasive HPV16-positive lesions using HLA-A2 tetramer complexes loaded with the E6-derived epitope KLPQLCTEL. In contrast, we could not detect E6-reactive T cells in healthy individuals. These data imply that the measurement of the HPV16 E7(11-19(20)) CD8(+)-T-cell response may reflect cross-reactivity with a common pathogen and that variant peptides may be employed to drive an effective cellular immune response against HPV.     

Human papillomavirus type 33 E7 peptides presented by HLA-DR*0402 to tumor-infiltrating T cells in cervical cancer

Several characteristics make human papillomavirus (HPV) amenable to vaccination. Anti-HPV-directed vaccines are based on the observation that HPV E6 and E7 oncoproteins are constitutively expressed in HPV-positive cervical cancer and may serve as tumor rejection antigens. Five HPV types (16, 18, 31, 33, and 45) account for 80% of cervical cancer. Until now, the type of immune response capable of mediating an effective antitumor response has not been defined. In order to define the anticancer-directed immune response in situ, we characterized CD4(+) and CD8(+) sorted T cells from peripheral blood lymphocytes, freshly harvested tumor tissue, and tumor-infiltrating lymphocytes (TIL) from a patient with cervical cancer. The HLA-DR-restricted CD4(+) T-cell receptor VB16-, VA10-, VA21-, and VA22-positive CD4(+) T-cell line derived from TIL recognizes autologous HLA-DR*0402(+) (HPV33(+)) cervical cancer cells, as determined by gamma interferon secretion. Testing of different peptides spanning the E7 gene revealed that the HPV33(73-87) peptide ASDLRTIQQLLMGTV represents the immunodominant epitope which can also be presented by the DR*0401 allele to TIL. Such major histocompatibility complex class II-presented peptides represent attractive candidates to augment T-cell responses directed against autologous tumor cells.     

Differences in TCR-Vβ Repertoire and Effector Phenotype between Tumor Infiltrating Lymphocytes and Peripheral Blood Lymphocytes Increase with Age

Tumor infiltrating lymphocytes (TIL) reflect the host''s anti-tumor immune response, and can be a valuable predictor of prognosis. However, many properties of TIL are not fully understood. In the present study, TCR-Vβ repertoires of cancer patients were primarily analyzed by flow cytometry. Abnormally expressed TCR-Vβ subfamilies were generally found in both TIL and peripheral blood lymphocytes (PBL) of each patient. Of note, increased patient age was associated with increasingly biased TCR-Vβ repertoire in TIL but not in PBL, and the dispersion degree of the differences of TCR-Vβ subfamilies between TIL and PBL correlated positively with age (P = 0.007). Utilizing immunoscope analysis, we identified the age-related reduction in TCR-Vβ diversity, but polyclonal pattern was predominant in significantly expanded TCR-Vβ subfamilies. In addition, we found that older patients possessed a decreased ratio of CD8⁺CD62L⁺ non-effector cells in TIL compared to PBL, implying age-related increase of CD8⁺CD62L⁻ effector cells in TIL. The colocalization analysis of CD8 and CD3, however, suggested the suppressed activity of these effector cells in tumor microenvironment. These findings further elucidate the properties of TIL, showing an increasing difference between TIL and PBL with age, which may provide insight for the development of effective immunotherapies for cancer patients of different ages.     

Activation markers on T cells infiltrating melanoma metastases after therapy with dinitrophenyl-conjugated vaccine

Treatment of metastatic melanoma patients with an autologous vaccine modified by the hapten, dinitrophenyl (DNP), produces a striking immunological effect: the induction of clinically evident inflammatory responses in metastatic tumors. Histological examination shows these tumors to be infiltrated with T lymphocytes. We studied the expression of activation markers on those cells and compared them with matched peripheral blood lymphocytes (PBL) and with lymphocytes extracted from metastases before treatment with DNP-conjugated vaccine. The median fraction of cells that were T cells in post-vaccine tumors was 41%, as compared with 9% in pre-treatment tumors, and those T cells were predominantly CD8⁺ (mean CD8/CD4 ratio=5.0). A high proportion of both pre- and posttreatment infiltrating T cells expressed HLA-DR (mean±SE=48%±4%), CD69 (56%±7%), and ganglioside GD3 (68%±5%). This distinguished them from matched PBL in which expression of those markers was significantly lower (HLA-DR=10%±2%; CD69=2%±0.4%; GD3=49%±4%). These changes were not accompanied by increased cell-surface expression of interleukin-2 (IL-2) receptors, either CD25 or p75, which were expressed by 1%–2% and 12% of tumor-infiltrating lymphocytes (TIL), respectively. The pattern of activation marker expression that we identified appears to be characteristic of tissue T cells with the memory phenotype. The low expression of IL-2 receptors could indicate functional impairment of TIL in situ, perhaps because of inhibitory molecules produced by melanoma cells.This work was supported by NIH grants CA 39248, CA 40358, and AR 39674 from the National Institutes of Health and by funds from the Nat Pincus Trust     

Prevalence of regulatory T cells is increased in peripheral blood and tumor microenvironment of patients with pancreas or breast adenocarcinoma

Regulatory T cells (T(reg)) that prevent autoimmune diseases by suppression of self-reactive T cells may also suppress the immune response against cancer. In mice, depletion of T(reg) by Ab therapy leads to more efficient tumor rejection. T(reg)-mediated suppression of antitumor immune responses may partly explain the poor clinical response to vaccine-based immunotherapy for human cancer. In this study, we measured the prevalence of T(reg) that coexpress CD4 and CD25 in the PBLs, tumor-infiltrating lymphocytes, and regional lymph node lymphocytes from 65 patients with either pancreas or breast cancer. In breast cancer patients (n = 35), pancreas cancer patients (n = 30), and normal donors (n = 35), the prevalence of T(reg) were 16.6% (SE 1.22), 13.2% (SE 1.13), and 8.6% (SE 0.71) of the total CD4(+) cells, respectively. The prevalence of T(reg) were significantly higher in breast cancer patients (p < 0.01) and pancreas cancer patients (p < 0.01) when compared with normal donors. In tumor-infiltrating lymphocytes and lymph node lymphocytes, the T(reg) prevalence were 20.2% (SE 3.93) and 20.1% (SE 4.3), respectively. T(reg) constitutively coexpressed CTLA-4 and CD45RO markers, and secreted TGF-beta and IL-10 but did not secrete IFN-gamma. When cocultured with activated CD8(+) cells or CD4(+)25(-) cells, T(reg) potently suppressed their proliferation and secretion of IFN-gamma. We conclude that the prevalence of T(reg) is increased in the peripheral blood as well as in the tumor microenvironment of patients with invasive breast or pancreas cancers. These T(reg) may mitigate the immune response against cancer, and may partly explain the poor immune response against tumor Ags.     

Cellular characteristics of peripheral blood lymphocytes and tumour-infiltrating lymphocytes in patients with gynaecological tumours

 Immunotherapy of gynaecological cancer with tumour-infiltrating lymphocytes (TIL) or peripheral blood lymphocytes (PBL) has become a valid treatment modality with varying degrees of success in obtaining an antitumour response. TIL consist of lymphocytes, mainly T cells and minor populations of natural killer cells or B cells. Conventional cytogenetic studies of tumour cells from patients with breast and ovarian cancer have shown multiple chromosomal abnormalities including chromosomes 7 and 12. This study was designed to analyse the surface further, as well as investigate the intracellular, characteristics of TIL by multicolour flow cytometry and the cytogenetic features by fluorescence in situ hybridization. Tumour cell, peripheral blood and TIL samples from 25 patients (15 ovarian tumours, 8 breast cancers, 1 uterine sarcoma, 1 cervical carcinoma) were analysed for their phenotype, the expression of major cytokines [interleukin-2 (IL-2), IL-4 and interferon γ (IFNγ)], their proliferation rate, their cytotoxic ability and for the presence of numerical aberrations of chromosomes 7 and 12. All the tumour cells showed a high frequency of numerical aberration in chromosomes 7 and 12, especially trisomies or tetrasomies and combined aberrations. Trisomies of both chromosomes also occured at a low percentage in TIL and PBL. Received: 20 June 1996 / Accepted: 4 January 1997     

Analysis of the immune reactivity of infiltrating and peripheral lymphocytes from patients with renal cell carcinoma by measuring cytokine secretion

 The immunological properties of tumor-infiltrating (TIL) and peripheral blood lymphocytes (PBL) from 29 patients with renal cell carcinomas were characterized with respect to their phenotypic expression and cytokine production. TIL were isolated from mechanically disaggregated tumor material and PBL from peripheral blood by gradient centrifugation. To eliminate all non-lymphoid cells, CD3-positive cells were specifically separated from these cell fractions with anti-CD3 magnetic beads. These pure CD3-positive PBL (CD3⁺PBL) and TIL (CD3⁺TIL) were cultured with pokeweed mitogen and the levels of the cytokines interleukin-1α (IL-1α), IL-1β, IL-2, interferon γ (IFNγ), and tumor necrosis factor α (TNFα) measured in the 4-day post-inductional cell culture supernatants. In all cell cultures a wide range of cytokine values was found, indicating a large variation in the immunological activity of the lymphocytes of each individual. When the cell cultures of the CD3⁺TIL and CD3⁺PBL were compared in each patient similar values for IL-1α, IL-1β, IFNγ and TNFα were found. However CD3⁺TIL produced significantly lower levels of IL-2 than CD3⁺PBL upon mitogenic stimulation. This may be due to a lower CD4/CD8 ratio in the CD3⁺TIL as compared to the CD3⁺PBL. These results suggest that there are no fundamental qualitative and quantitative differences in the lymphokine-producing capacity of CD3⁺TIL and CD3⁺PBL derived from patients with renal cell carcinomas. Received: 8 August 1995 / Accepted: 23 January 1996     

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     

Tumor-infiltrating lymphocytes predict response to chemotherapy in patients with advance non-small cell lung cancer

Accumulating preclinical evidence suggests that anticancer immune responses contribute to the success of chemotherapy. The predictive significance of tumor-infiltrating lymphocytes (TILs) for response to neoadjuvant chemotherapy in non-small cell lung cancer (NSCLC) remains unknown. The aim of this study was to investigate the prognostic and predictive value of TIL subtypes in patients with advanced NSCLC treated with platinum-based chemotherapy. In total, 159 patients with stage III and IV NSCLC were retrospectively enrolled. The prevalence of CD3(+), CD4(+), CD8(+) and Foxp3(+) TILs was assessed by immunohistochemistry in tumor tissue obtained before chemotherapy. The density of TILs subgroups was treated as dichotomous variables using the median values as cutoff. Survival curves were estimated by the Kaplan-Meier method, and differences in overall survival between groups were determined using the Log-rank test. Prognostic effects of TIL subsets density were evaluated by Cox regression analysis. The presence of CD3(+), CD4(+), CD8(+), and FOXP3(+) TILs was not correlated with any clinicopathological features. Neither the prevalence of TILs nor combined analysis displayed obvious prognostic performances for overall survival in Cox regression model. Instead, higher FOXP3(+)/CD8(+) ratio in tumor sites was an independent factor for poor response to platinum-based chemotherapy in overall cohort. These findings suggest that immunological CD8(+) and FOXP3(+)Tregs cell infiltrate within tumor environment is predictive of response to platinum-based neoadjuvant chemotherapy in advanced NSCLC patients. The understanding of the clinical relevance of the microenvironmental immunological milieu might provide an important clue for the design of novel strategies in cancer immunotherapy.     

Recognition of a new ARTC1 peptide ligand uniquely expressed in tumor cells by antigen-specific CD4+ regulatory T cells

CD4(+) regulatory T (Treg) cells play an important role in the maintenance of immunological self-tolerance by suppressing immune responses against autoimmune diseases and cancer. Yet very little is known about the natural antigenic ligands that preferentially activate CD4(+) Treg cells. Here we report the establishment of tumor-specific CD4(+) Treg cell clones from tumor-infiltrating lymphocytes (TILs) of cancer patients, and the identification of an Ag recognized by Treg cells (ARTC1) gene encoding a peptide ligand recognized by tumor-specific TIL164 CD4(+) Treg cells. The mutations in a gene encoding an ARTC1 in 164mel tumor cells resulted in the translation of a gene product containing the peptide ligand recognized by CD4(+) Treg cells. ARTC1 peptide-activated CD4(+) Treg cells suppress the physiological function (proliferation and IL-2 secretion) of melanoma-reactive T cells. Furthermore, 164mel tumor cells, but not tumor lysates pulsed on B cells, were capable of activating TIL164 CD4(+) Treg cells. These results suggest that tumor cells may uniquely present an array of peptide ligands that preferentially recruit and activate CD4(+) Treg cells in sites where tumor-specific self-peptide is expressed, leading to the induction of local and tumor-specific immune suppression.     

Detection of gastric carcinoma-associated antigen MG7-Ag in human sera using surface plasmon resonance sensor

Background: MG7-Ag is a kind of gastric cancer-specific tumor-associated antigen and has been investigated to serve as a marker of gastric cancer for early diagnosis. Methods: Surface plasmon resonance (SPR) sensor was used for the detection of MG7-Ag in the sera of gastric cancer patients to develop an innovative, simple and rapid assay method for early diagnosis. The specific monoclonal MG7 antibodies were used as capture and detection receptors which were immobilized on the surface of SPR sensor chips for MG7-Ag identification in the human sera. The measurements include 9 cases of gastric cancer patients and 2 cases of healthy blood donors and a MKN45 cancer cell lysate solution sample for positive control. Results: The binding of MG7-Ag onto the sensor surface was observed from SPR spectra. The sera of most gastric cancer patients revealed much higher expression level of MG7-Ag than healthy human sera did in SPR measurement. Conclusion: The initial results demonstrate that the SPR biosensor has the potential for its application in the early diagnosis of gastric cancer. However, more tests need to be done to confirm the detection limitation and the criterion for cancer risk evaluation in early diagnosis.     

Split T cell tolerance against a self/tumor antigen: spontaneous CD4+ but not CD8+ T cell responses against p53 in cancer patients and healthy donors

Analyses of NY-ESO-1-specific spontaneous immune responses in cancer patients revealed that antibody and both CD4(+) and CD8(+) T cell responses were induced together in cancer patients. To explore whether such integrated immune responses are also spontaneously induced for other tumor antigens, we have evaluated antibody and T cell responses against self/tumor antigen p53 in ovarian cancer patients and healthy individuals. We found that 21% (64/298) of ovarian cancer patients but no healthy donors showed specific IgG responses against wild-type p53 protein. While none of 12 patients with high titer p53 antibody showed spontaneous p53-specific CD8(+) T cell responses following a single in vitro sensitization, significant p53-specific IFN-γ producing CD4(+) T cells were detected in 6 patients. Surprisingly, similar levels of p53-specific CD4(+) T cells but not CD8(+) T cells were also detected in 5/10 seronegative cancer patients and 9/12 healthy donors. Importantly, p53-specific CD4(+) T cells in healthy donors originated from a CD45RA(-) antigen-experienced T cell population and recognized naturally processed wild-type p53 protein. These results raise the possibility that p53-specific CD4(+) T cells reflect abnormalities in p53 occurring in normal individuals and that they may play a role in processes of immunosurveillance or immunoregulation of p53-related neoplastic events.     

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.     

Thymic export function and T cell homeostasis in patients with relapsing remitting multiple sclerosis

Multiple sclerosis (MS) is an inflammatory and possibly autoimmune mediated demyelinating disease of the CNS. Autoimmunity within the CNS may be triggered by dysfunction of peripheral immune tolerance mechanisms via changes in the homeostatic composition of peripheral T cells. We have assessed the release of naive T lymphocytes from the thymus in patients with relapsing remitting MS (RRMS) to identify alterations in the equilibrium of the peripheral T cell compartment. Thymic T cell production was estimated by measuring TCR excision circles (TRECs) as a traceable molecular marker in recent thymic emigrants. A total of 46 treatment-naive patients with active RRMS and 49 gender- and age-matched healthy persons were included in the study. The levels of TREC-expressing CD4(+) and CD8(+) T lymphocytes were significantly decreased in MS patients, and TREC quantities overall matched those of 30 years older healthy individuals. The average concentrations of TRECs/10(6) CD4(+) and CD8(+) T lymphocytes derived from MS patients and healthy donors were 26 x 10(3)/10(6) and 28 x 10(3)/10(6) vs 217 x 10(3)/10(6) and 169 x 10(3)/10(6), respectively. To account for any influence of T cell proliferation on TREC levels, we assayed T lymphocytes from additional patients with MS and normal individuals for telomere length (n = 20) and telomerase activity (8 MS patients, 16 controls), respectively. There were no significant differences between CD4(+) and CD8(+) T cells from MS patients and controls. Altogether, our findings suggest that an impaired thymic export function and, as a consequence, altered ability to maintain T cell homeostasis and immune tolerance may play an important pathogenic role in RRMS.     

Comparison of recombinant-interleukin-2-activated peripheral blood and tumor-infiltrating lymphocytes of patients with epithelial ovarian carcinoma: Cytotoxicity,growth kinetics and phenotype

Summary We have compared the growth and tumordirected cytotoxic efficacy of recombinant-interleukin-2-(rIL-2)-activated peripheral blood (PBL) and tumor-infiltrating lymphocytes (TIL) from patients with epithelial ovarian carcinoma. These studies demonstrated that TIL and PBL displayed similar levels of cytotoxicity and a broad range of target cell killing, as exemplified by their reactivity against autologous and allogeneic ovarian tumors as well as against tumor cell lines. No specificity of autologous tumor cell killing was manifested by TIL. Even though TIL of some patients showed higher proliferative activity (especially at the later times in rIL-2 culture) this was not a general phenomenon. In fact, in one case TIL did not proliferate at all, and in the other case the PBL proliferated more actively. While the cultures were composed primarily of CD3⁺ lymphocytes, the major cytotoxic cells displayed the CD56⁺ and CD16⁺ phenotype. Addition of OKT3 mAb to rIL-2 cultures resulted in an increased proliferative index, but showed only a minor effect on the cytotoxic potential of cultured lymphocytes. The therapeutic potential of rIL-2-activated TIL and PBL is discussed.Recipient of the Florence Maude Thomas Cancer Research Professorship     

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.     

Defective adhesion in tumor infiltrating CD8+ T cells

CD8(+) tumor-infiltrating lymphocytes (TIL) are defective in cytolysis due to tumor-induced inhibition of proximal TCR-mediated signaling, a defect that is relieved upon purification and brief culture. We show in this study that frequency of conjugation in vitro of nonlytic TIL with tumor cells is low in comparison with their lytic counterparts, and the strength of interaction and duration of conjugation are also reduced. Previous reports show that p56(lck) activation is required for TCR-initiated LFA-1 avidity up-regulation, raising the question: is low LFA-1 avidity the basis of reduced TIL conjugation frequency? When stimulated with phorbol ester, nonlytic TIL bind purified ICAM-1 equivalently as lytic TIL, suggesting that LFA-1 can be activated if proximal TCR signaling is bypassed. However, when treated with phorbol ester, the conjugation frequency of nonlytic TIL does not increase. CD2 and CD8 also mediate T cell adhesion to cognate target cells and are both expressed at lower levels in nonlytic TIL in addition to being excluded from the immune synapse formed upon conjugation. Collectively, these results imply that adhesion defects in nonlytic TIL result from a combination of decreased cell surface levels of adhesion molecules, deficient LFA-1 activation, and the failure to recruit essential adhesion receptors to the membrane contact site formed with cognate target cells.     

CD4+ T cell response to the human acetylcholine receptor alpha subunit in myasthenia gravis. A study with synthetic peptides

The production of antinicotinic acetylcholine receptor (AcChR) antibodies in myasthenia gravis (MG) is modulated by specific Th (CD4+) lymphocytes that can recognize epitopes on the denatured AcChR alpha subunit. Thirty-two overlapping synthetic peptides corresponding to the complete sequence of human AcChR alpha subunit were used to investigate the anti-alpha subunit response of unselected lymphocytes and of CD8(+)-depleted, CD4(+)-enriched lymphocytes from the blood of nine MG patients and from four healthy controls. One subject was a newly diagnosed MG patient that was tested three times after the development of the disease. An anti-AcChR response of the CD4(+)-enriched cells was present that could be detected only after removal of the CD8+ population and that seems to be related to the clinical conditions of the patient. The high basal rate of the cell proliferation of the unselected unstimulated blood lymphocytes and the normal basal rate observed for the CD8(+)-depleted population suggested the presence of activated CD8+ cells. The study of surface markers of the T cells confirmed the existence of activated CD8+ and CD4+ cells in numbers correlated with the severity of the disease and the results of the in vitro response of the T cells. The anti-AcChR activity of the CD4+ cells in MG may be a useful marker of the activity of the disease and it seems to be influenced by activated CD8+ cells present in the patients' blood.     

Human peripheral blood leukocyte engraftment into SCID mice: critical role of CD4(+) T cells

We examined the influence of donor T lymphocytes on human peripheral blood leukocytes (PBL) engraftment into severe combined immune deficient (SCID) mice. Mice were injected with unfractionated or subset-depleted human PBL, and treated at various times with OKT3, a cytotoxic monoclonal antibody against human CD3(+) T lymphocytes. PBL engraftment, high levels of human Ig, and high incidence of lymphoproliferative disease (lpd) were found in mice transplanted with unfractionated PBL and CD8- or CD14-depleted PBL, and in mice treated with OKT3 at distance from PBL transfer. Animals xenografted with CD3- or CD4-depleted PBL, or treated at transplantation time with OKT3, had very low levels of human Ig and did not develop lpd. PBL engraftment was minimal or absent in these animals, as determined by immunohistochemistry, dot-blot, and RT-PCR analyses. These results demonstrate that the presence of donor CD4(+) T lymphocytes at transplantation time is necessary for observing human PBL engraftment into SCID mice, an essential condition for human Ig production and lpd development.