Targeting TNF-α to neoangiogenic vessels enhances lymphocyte infiltration in tumors and increases the therapeutic potential of immunotherapy

Abnormal tumor vasculature impairs T lymphocyte adhesion to endothelial cells and lymphocyte extravasation into neoplastic tissues, limiting the therapeutic potential of both active and adoptive immunotherapies. We have found that treatment of tumor-bearing mice with NGR-TNF, a Cys-Asn-Gly-Arg-Cys peptide-TNF fusion product capable of altering the endothelial barrier function and improving drug penetration in tumors, associated with the intratumor upregulation of leukocyte-endothelial cell adhesion molecules, the release of proinflammatory cytokines and chemokines, and the infiltration of tumor-specific effector CD8(+) T cells. As a result, NGR-TNF enhanced the therapeutic activity of adoptive and active immunotherapy, delaying tumor growth and prolonging survival. Furthermore, we have found that therapeutic effects of these combinations can be further increased by the addition of chemotherapy. Thus, these findings might be relevant for the design of novel immunotherapeutic approaches for cancer patients.     

FRET detection of lymphocyte function–associated antigen-1 conformational extension

Lymphocyte function–associated antigen 1 (LFA-1, CD11a/CD18, αLβ2-integrin) and its ligands are essential for adhesion between T-cells and antigen-presenting cells, formation of the immunological synapse, and other immune cell interactions. LFA-1 function is regulated through conformational changes that include the modulation of ligand binding affinity and molecular extension. However, the relationship between molecular conformation and function is unclear. Here fluorescence resonance energy transfer (FRET) with new LFA-1–specific fluorescent probes showed that triggering of the pathway used for T-cell activation induced rapid unquenching of the FRET signal consistent with extension of the molecule. Analysis of the FRET quenching at rest revealed an unexpected result that can be interpreted as a previously unknown LFA-1 conformation.     

Induction of tumor-specific T lymphocyte responses in vivo by prothymosin α

We have recently reported that administration of Pro T to DBA/2 mice before the inoculation of syngeneic L1210 leukemic cells prolonged the survival of these animals by (a) inducing tumoricidal peritoneal macrophages, (b) enhancing natural killer (NK) and inducing lymphokine-activated killer (LAK) activities in splenocytes and (c) inducing the production of interleukin-2 and tumor necrosis factor [Papanastasiou et al. (1992) Cancer Immunol Immunother 35:145; Baxevanis et al. (1994) Cancer Immunol Immunother 38:281]. In this report we demonstrate that Pro T , when administered simultaneously with L1210 tumor cells, is capable of generating in DBA/2 animals tumorspecific CD8⁺ cytotoxic T lymphocytes (CTL). The Pro T -induced CD8⁺ CTL lysed their syngeneic L1210 targets in a major histocompatibility complex (MHC)-restricted fashion since monoclonal antibodies (mAb) against the H-2K^d allelic product could inhibit the cytotoxic response. Mice receiving only Pro T developed non-MHC-restricted cytotoxic activity (NK, and LAK activities) whereas those receiving Pro T and L1210 tumor cells developed both MHC-restricted (CTL) and non-MHC-restricted cytotoxic activities and survived longer. The Pro T -induced CD8⁺ CTL activity was regulated by Pro T -induced L1210-specific syngeneic CD4⁺ cells. This was shown in two different ways: first, CD8⁺-cell-mediated cytotoxic responses against L1210 targets were associated with L1210-specific and MHC-restricted proliferative responses of syngeneic CD4⁺ cells and, second, CD4⁺ cells from mice that had received both Pro T and L1210 tumor cells could enhance in vitro the otherwise weak, MHC-restricted and L1210-specific cytotoxicity of syngeneic CD8⁺ cells from mice that had received only L1210 cells. Our data suggest that Pro T is capable of inducing nonspecific, as well as tumor-specific CTL responses in vivo. This is of importance since Pro T may prove to be useful in clinical protocols aimed at cancer immunotherapy.This work was supported by a CEC grant to Dr. M. Papamichail     

B lymphocyte differentiation and the control of IgM μ chain expression

The biosynthesis of IgM μ polypeptides was studied in isolated populations of normal B lymphocytes and in various IgM-producing cell lines. Membrane and secretory μ were found to be distinct polypeptide species, with separate biosynthetic intermediates from the translation stage onwards. Various B cell populations express different portions of the two biosynthetic μ pathways. Normal, resting small B lymphocytes do not secrete detectable μ and lack the later intermediate forms of secretory μ. However, they apparently possess, and translate, secretory μ mRNA, and show earlier secretory μ intermediate protein forms. Resting B cells thus exert posttranslational control over secretory μ expression. Since the later intermediate forms of secretory μ, which are lacking in small B cells, are due to carbohydrate modifications of the μ chain, it is suggested that the carbohydrate portion may be involved in regulating the expression of the secretory μ glycoprotein. In contrast to small B cells, highly differentiated IgM-secreting cells control the expression of membrane μ by a pretranslational mechanism.     

β-d-N-Acetylglucosaminidase,a new cytochemical marker of human lymphocyte subpopulations

Summary -d-N-acetylglucosaminidase staining characteristics of rosetted or non-rosetted normal and malignant lymphoid cells were compared with those observed after nonspecific esterase and acid phosphatase staining. With the three cytochemical techniques a similar staining pattern was observed in T cells (E-rosettes), their subpopulations T and T, B cells and the non-T, non-B cells, as well as in the T cell populations defined with the monoclonal antibodies OKT3,4 and 8. T cells mostly diplayed a dot-like reaction, T and the non-T, non-B cells a fine to heavy granular reaction, while most B cells were negative. OKT4 and OKT8 positive lymphocytes showed for the larger part a dot-like staining pattern, however, the frequency of cells with a granular pattern was distinctly higher in the OKT8, than in the OKT4 positive cells.E(+)mIg(–) and E(–)mIg(–) A.L.L. blasts stained either with a dot-like or granular pattern or failed to react when stained cytochemically for -d-N-acetylglucosaminidase, nonspecific esterase and acid phosphatase activity. Only in a few instances a discrepancy was observed between the types of staining for esterase and acid phosphatase on one hand and those for -d-N-acetylglucosaminidase on the other.     

Transient β-glucuronidase activity after infiltration of Arabidopsis thaliana by Agrobacterium tumefaciens

Transient expression of the β-glucuronidase (GUS) gene introduced into Arabidopsis thaliana intact plants by T-DNA after vacuum infiltration of Agrobacterium tumefaciens was followed. The first incidence of GUS activity was found 2 - 3 d after treatment and a peak of activity one week after treatment in both A. thaliana races, Columbia and C24. GUS activity was sharply increased by cultivation of Arabidopsis plants at elevated temperature (29 °C) compared to cultivation at 25 °C. The density of inocula also influenced the GUS activity. This revised version was published online in July 2006 with corrections to the Cover Date.     

Oncogene amplification correlates with dense lymphocyte infiltration in human breast cancers: A role for hematopoietic growth factor release by tumor cells?

One hundred six primary breast cancer samples were analysed for c-erbB2, int-2, and c-myc gene amplification. Surgically confirmed nodal involvement was observed in 42%. Level of gene amplification was studied by Southern and/or slot blot techniques. Amplified c-erbB2 gene sequences were present in 21.5% of all samples. Int-2 was amplified in 13.1% and c-myc was amplified in 10.3%. In a non-parametric test (Kruskal-Wallis) a strong negative association was found between high levels of c-erbB2 amplification and absence of estrogen receptor (ER) (P = .0009) or progesterone receptor (PR) (P = .011) expression. No correlations were found between all or high levels of amplification of each oncogene separately or combined with T, N, grade, multifocality of tumor, or associated carcinoma in situ. There was a trend approaching statistical significance for patients with c-erbB2 amplifications to have positive lymph nodes at surgery (P = 0.09). A somewhat surprising finding however was a very strong association between oncogene amplification and dense lymphocyte infiltration of the tumor (P = .05). This correlation is even stronger when only high levels of amplification are considered, either for each oncogene separately (P = .0048) or in combination (P = .0007). We propose that malignant cell cytokine production may help explain this observation.     

Alterations of cardiac and lymphocyte β-adrenoceptors in rat with chronic heart failure

The alterations of cardiac and lymphocyte β-adrenoceptors were observed in the rats with chronic heart failure produced by constriction of both abdominal aorta and renal artery. The results showed that β1-adrenocep-tor density and mRNA levels were increased, whereas these levels remained unchanged for β2 The concentration-contractile response curve for isoproterenol was shifted to the right in cardiac atrium, whereas the concentration-cAMP accumulation response curve for isoproterenol in myocardium was not changed. The number of β-adrenoceptors in blood lymphocyte was markedly reduced. Thus in the heart-failure rats the density of cardiac β-adrenoceptor was increased accompanying reduced β-adrenoceptor-mediated positive inotropic response, suggesting a post adenylate cyclase dys-function or impaired contractile components. In contrast, the alteration of β-adrenoceptor in lymphocyte is consistent with the reduced β-adrenoceptor-mediated inotropic response in heart.     

Expansion and contraction of the cytotoxic T lymphocyte response—An optimal control approach

The kinetics of the cytotoxic T lymphocyte (CTL) response against intracellular pathogens has been found to have many stereotypical features that appear to be programmed early in the infection. We explain these findings here in terms of CTL response kinetics that minimize the probability that a pathological symptom will occur in association with the infection and its eradication. We assume that both the infection and the CTLs contribute to this pathology. We find that contraction kinetics is influenced by the relative pathogenicities of infection and CTLs, as well as on the virulence of the infection and the efficiency of the CTLs, but not by the magnitude of expansion or the dose and duration of infection. Our analysis explains the finding that the duration of the CTL expansion is highly stereotypical, with the maximum expansion of the CTL response dependent on the dose of the infection. Finally, we show that the stereotypical nature of CTL kinetics relies upon stringent regulation of the rates at which CTLs proliferate and die.     

Alterations of cardiac and lymphocyte β- adrenoceptors in rat with chronic heart failure

The alterations of cardiac and lymphocyte β-adrenoceptors were observed in the rats with chronic heart failure produced by constriction of both abdominal aorta and renal artery. The results showed that β₁-adrenoceptor density and mRNA levels were increased, whereas these levels remained unchanged for β₂. The concentrationcontractile response curve for isoproterenol was shifted m the right in cardiac atrium, whereas the concentration-CAMP accumulation response curve for isoproterenol in myocardium was not changed. The number of β-adrenoceptom in blood lymphocyte was markedly reduced. Thus in the heart-failure rats the density of cardiac β-adrenoceptor was increased accompanying reduced β-adrenoceptormediated positive inotropic response, suggesting a post adenylate cyclase dysfunction or impaired contractile components. In contrast, the alteration of β-adrenoceptor in lymphocyte is consistent with the reduced β-adrenoceptor-mediated inotropic response in heart.     

Phospholipase C–mediated hydrolysis of PIP2 releases ERM proteins from lymphocyte membrane

Mechanisms controlling the disassembly of ezrin/radixin/moesin (ERM) proteins, which link the cytoskeleton to the plasma membrane, are incompletely understood. In lymphocytes, chemokine (e.g., SDF-1) stimulation inactivates ERM proteins, causing their release from the plasma membrane and dephosphorylation. SDF-1–mediated inactivation of ERM proteins is blocked by phospholipase C (PLC) inhibitors. Conversely, reduction of phosphatidylinositol 4,5-bisphosphate (PIP2) levels by activation of PLC, expression of active PLC mutants, or acute targeting of phosphoinositide 5-phosphatase to the plasma membrane promotes release and dephosphorylation of moesin and ezrin. Although expression of phosphomimetic moesin (T558D) or ezrin (T567D) mutants enhances membrane association, activation of PLC still relocalizes them to the cytosol. Similarly, in vitro binding of ERM proteins to the cytoplasmic tail of CD44 is also dependent on PIP2. These results demonstrate a new role of PLCs in rapid cytoskeletal remodeling and an additional key role of PIP2 in ERM protein biology, namely hydrolysis-mediated ERM inactivation.     

Cooperation of dendritic cells with naïve lymphocyte populations to induce the generation of antigen-specific antibodies in vitro

The production of monoclonal antibodies by hybridoma technology is dependent on lymphocytes taken from vertebrates which have to be immunized against the corresponding antigen. We present here our first experiments which should allow the replacement of this in vivo immunization step by an in vitro immunization procedure. This work provides new possibilities for the specific activation of immune cells in order to use them for the generation of antibodies which are not of murine origin. Bone marrow-derived dendritic cells were loaded with antigen and co-cultured with naïve T and B lymphocytes of non-immunized mice. The interaction and activation of the different cell types were investigated by measuring the expression of specific cell surface markers, the release of activation-dependent interleukins and the secretion of antigen-specific antibodies. We could demonstrate that dendritic cells process and present antigen fragments and activate T cells, that T cells proliferate and release activation-induced interleukins, and that B cells maturate under the influence of activated T cells and secrete antigen-specific antibodies.     

Amplification of human APO(a) kringel 4–37 from blood lymphocyte DNA

We have been able to amplify the lysine binding pocket region of human apo(a) kringle type 5 starting from the DNA isolated from peripheral blood lymphocytes. This development now permits the identification of Lp(a) mutants that by lacking their ability of bind to lysine/fibrin would have a lesser thrombogenic potential.     

Human T lymphocyte activation in the presence of acute myelogenous leukaemia blasts: studies of allostimulated interferon-γ secretion

 Normal peripheral blood mononuclear cells (PBMC responders) were cultured together with non-irradiated allogeneic PBMC (more than 95% leukaemia blasts) derived from patients with acute leukaemia (referred to as leukaemic PBMC stimulators). Cytokine secretion was determined as cytokine concentrations in supernatants. Both normal PBMC and enriched CD4⁺ and CD8⁺ T cells responded to allostimulation with interferon (IFNγ) secretion. Interleukin-1 (IL-1) receptor antagonist and IL-2-neutralizing antibodies decreased IFNγ secretion. Exogenous IL-1β, IL-2 and IL-7 increased allostimulated IFNγ secretion, whereas decreased levels were seen in the presence of IL-6, IL-10 and granulocyte-colony-stimulating factor (G-CSF). During allorecognition IFNγ -neutralizing antibodies decreased acute myelogenous leukaemia (AML) blast secretion of G-CSF. We conclude that (i) both CD4⁺ and CD8⁺ T cells show allostimulated cytokine secretion in response to allogeneic stimulator cells containing a dominating population of native, cytokine-secreting leukaemia blasts, and (ii) IFNγ released during this response can modulate the function of allogeneic AML blasts. Received: 4 June 1996 / Accepted: 15 October 1996     

Suppression of cytotoxic T lymphocyte activity by γ/δ T cells in tumor-bearing mice

Spleen cells derived from tumor-bearing mice prove useful for the elucidation of the mechanism determining how tumor cells evade cytotoxic T lymphocytes (CTL) in tumor-bearing hosts. Our data indicate that inactive CTL or precursor CTL specific for tumor antigens are present among lymphocytes of tumor-bearing mice. However, their activity is inhibited by a soluble factor produced by other cells present in the same source. Inhibition of the cytolytic reaction was also detected in the culture supernatant of spleen cells obtained from normal mice, precultured in the presence of tumor cell culture supernatant and interleukin-2 (IL-2). Cell-depletion and cell-purification studies let us conclude that cells that produced the CTL-inhibitory factor (CTL-IF) were / T cells. The / T cells that were activated in vivo in tumor bearers were able to produce CTL-IF after isolation and in vitro culture. Maximum activation of / T cells was achieved by antigenic stimulation and by suppression of cells that interfered with the activation of / T cells. CTL-IF, which was assayed by use of CTL clones, did not show antigen specificity. Inhibition depended on a relatively heat- and acidstable, but alkali-labile molecule with a molecular mass of less than 10 kDa. The latter characteristics imply that CTL-IF does not resemble any of the known lymphokines produced by / T cells. These observations emphasize the crucial role of the / T cells in the escape of tumor cells from the attack of tumorspecific CTL.