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C G Figdor

Publications and source records attributed to C G Figdor.

At least 109 records · Page 6Linked to original sources
PubMed1994

Molecular characterization of the melanocyte lineage-specific antigen gp100.

The glycoproteins recognized by monoclonal antibody (mAb) NKI-beteb are among the best diagnostic markers for human melanoma because their expression is restricted to melanocytic cells. Recently, we isolated a cDNA clone, termed gp100-c1, which confers immunoreactivity not only to mAb NKI-beteb, but also to two other mAbs used to diagnose malignant melanoma, HMB-50 and HMB-45. In this report, we demonstrate that gp100-c1 cDNA encodes glycoproteins of 100 kDa (gp100) and 10 kDa (gp10) which are recognized by these mAbs in human melanoma cells. The translation product deduced from the open reading frame present in gp100-c1 cDNA is highly homologous to another melanocyte-specific protein, Pmel17. Nucleotide sequence analysis of genomic DNA indicates that the transcripts corresponding to gp100 and Pmel17 cDNAs originate from a single gene via alternative splicing. In all normal and malignant melanocytic cells analyzed, gp100 and Pmel17 RNAs are simultaneously expressed.

Amino Acid Sequence↗
PubMed1994

Changes in actin organization during the cytotoxic process.

Changes in organization of F-actin during the cytotoxic process between NK and K562 cells have been observed and studied using confocal laser scanning microscopy and quantitative fluorescence microscopy. An increase in F-actin content and orientation of F-actin towards the target cell have been observed in conjugated NK cells. The increase in F-actin content probably reflects activation of the NK cell for the killing process. An increase in F-actin content in the conjugated K562 cell, occurring simultaneously with the appearance of filamentous actin structures that often originated/ended at the contact place with the NK cell, was also observed. These changes were delayed compared to the increase in F-actin content in the NK cell and were accompanied by increasing cytotoxic activity. This indicates that they were results of the interaction of the K562 cell with the activated NK cell. The possible role of target cell microfilaments in the cytotoxic process is addressed.

Actin Cytoskeleton↗
PubMed1994

Melanocyte lineage-specific antigen gp100 is recognized by melanoma-derived tumor-infiltrating lymphocytes.

We recently isolated a cDNA clone that encodes the melanocyte lineage-specific antigen glycoprotein (gp)100. Antibodies directed against gp100 are an important tool in the diagnosis of human melanoma. Since the gp100 antigen is highly expressed in melanocytic cells, we investigated whether this antigen might serve as a target for antimelanoma cytotoxic T lymphocytes (CTL). Here, we demonstrate that cytotoxic tumor-infiltrating lymphocytes (TIL) derived from a melanoma patient (TIL 1200) are directed against gp100. HLA-A2.1+ melanoma cells are lysed by TIL from this patient. In addition, murine double transfectants, expressing both HLA-A2.1 and gp100, are lysed by TIL 1200, whereas transfectants expressing only HLA-A2.1 are not susceptible to lysis. Furthermore, the HLA-A2.1+ melanoma cell line BLM, which lacks gp100 expression and is resistant to lysis, becomes susceptible after transfection of gp100 cDNA. Finally, HLA-A2.1+ normal melanocytes are lysed by TIL 1200. These data demonstrate that the melanocyte differentiation antigen gp100 can be recognized in the context of HLA-A2.1 by CTL from a melanoma patient. Gp100 may therefore constitute a useful target for specific immunotherapy against melanoma, provided that no unacceptable cytotoxicity towards normal tissue is observed.

Animals↗
PubMed1994

Distinct binding of T lymphocytes to ICAM-1, -2 or -3 upon activation of LFA-1.

LFA-1 (CD11a/CD18) mediates leukocyte adhesion by binding to one of its ligands: ICAM-1, ICAM-2 or ICAM-3. Here, we investigated whether stimuli known to induce adhesion to ICAM-1 were also capable of inducing LFA-1-mediated adhesion of T lymphocytes to ICAM-2 and -3 transfectants. We observed that phorbol 12-myristate 13-acetate, Mn2+, cross-linking of CD3 or activating antibodies against LFA-1 enhanced LFA-1-mediated T cell adhesion to ICAM-2 and -3, although to a lesser extent than to ICAM-1. These results indicate that, similar to what has been reported for adhesion to ICAM-1, activation of LFA-1 is also required for adhesion to ICAM-2 and -3. Furthermore, the results suggest that ICAM-1 is the major ligand for LFA-1 on activated T lymphocytes. Interestingly, we observed that in contrast to activating antibodies against CD18, activating antibodies against CD11a were incapable of inducing adhesion of LFA-1 to all three ligands. The antibody MEM-83 stimulated binding to ICAM-1, while at the same time inhibiting the interaction of LFA-1 with ICA8M-2 and -3. The antibody NKI-L16 selectively induced adhesion to ICAM-1 and -2, but not to ICAM-3. Our results suggest that different conformations of LFA-1 are required to support adhesion to ICAM-1, -2 or -3, and that ligands may bind on different sites of the LFA-1 molecule.

Animals↗
PubMed1994

Extracellular Ca2+ modulates leukocyte function-associated antigen-1 cell surface distribution on T lymphocytes and consequently affects cell adhesion.

Transition of leukocyte function-associated antigen-1 (LFA-1), from an inactive into an activate state depends on the presence of extracellular Mg2+ and/or Ca2+ ions. Although Mg2+ is directly involved in ligand binding, the role of Ca2+ in LFA-1 mediated adhesion remained obscure. We now demonstrate that binding of Ca2+, but not Mg2+, directly correlates with clustering of LFA-1 molecules at the cell surface of T cells, thereby facilitating LFA-1-ligand interaction. Using a reporter antibody (NKI-L16) that recognizes a Ca(2+)-dependent epitope on LFA-1, we found that Ca2+ can be bound by LFA-1 with different strength. We noticed that weak binding of Ca2+ is associated with a dispersed LFA-1 surface distribution on T cells and with non-responsiveness of these cells to stimuli known to activate LFA-1. In contrast, stable binding of Ca2+ by LFA-1 correlates with a patch-like surface distribution and vivid ligand binding after activation of LFA-1. Mg(2+)-dependent ligand binding does not affect binding of Ca2+ by LFA-1 as measured by NKI-L16 expression, suggesting that Mg2+ binds to a distinct site, and that both cations are important to mediate adhesion. Only Sr2+ ions can replace Ca2+ to express the L16 epitope, and to induce clustering of LFA-1 at the cell surface. We conclude that Ca2+ is involved in avidity regulation of LFA-1 by clustering of LFA-1 molecules at the cell surface, whereas Mg2+ is important in regulation of the affinity of LFA-1 for its ligands.

Calcium↗
PubMed1993

Effects of IL-13 on phenotype, cytokine production, and cytotoxic function of human monocytes. Comparison with IL-4 and modulation by IFN-gamma or IL-10.

Recently, we described the cloning and expression of a human cDNA which is the homologue to P600, a gene transcribed by mouse Th2 clones. Based on its activities on human monocytes and B cells this gene was designated IL-13. In the present study we investigated the effects of IL-13 alone or in combination with IL-4, IFN-gamma, or IL-10 on human monocytes. IL-13 induced significant changes in the phenotype of monocytes. Like IL-4, it enhanced the expression of CD11b, CD11c, CD18, CD29, CD49e (VLA-5), class II MHC, CD13, and CD23, whereas it decreased the expression of CD64, CD32, CD16, and CD14 in a dose-dependent manner. IL-13 induced up-regulation of class II MHC Ag and its down-regulatory effects on CD64, CD32, and CD16 expression were prevented by IL-10. IFN-gamma could also partially prevent the IL-13-induced down-regulation of CD64, but not that of CD32 and CD16. However, IL-13 strongly inhibited spontaneous and IL-10- or IFN-gamma-induced ADCC activity of human monocytes toward anti-D coated Rh+ erythrocytes, indicating that the cytotoxic activity of monocytes was inhibited. Furthermore, IL-13 inhibited production of IL-1 alpha, IL-1 beta, IL-6, IL-8, IL-10, IL-12 p35, IL-12 p40, macrophage inflammatory protein-1 alpha, granulocyte/macrophage-CSF, granulocyte-CSF, IFN-alpha, and TNF alpha by monocytes activated with LPS. In contrast, IL-13 enhanced the production of IL-1 ra by these cells. Similar results on cytokine production were observed or have been obtained with IL-4. Thus IL-13 shares most of its activities on human monocytes with IL-4, but no additive or synergistic effects of IL-4 and IL-13 on human monocytes were observed, suggesting that these cytokines may share common receptor components. Taken together, these results indicate that IL-13 has anti-inflammatory and important immunoregulatory activities.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1993

De-novo expression of CD44 and survival in gastric cancer.

We have examined the cell surface molecule CD44, which is attracting interest because of reports that isoforms are associated with metastasis. The prognostic value of CD44 expression has yet to be assessed for a solid tumour. Benign (59) and malignant (primary 61, metastatic 59) gastric tissues were examined with antibodies directed at epitopes common to known CD44 isoforms. Normal mucosa was CD44 negative. In atrophic gastritis and intestinal metaplasia expression was restricted to the epithelial cells of the basal glands and was positively correlated with an increased leucocyte infiltrate and with the expression of HLA DR by mucosal cells. These observations suggest a role for chronic inflammation in the induction of CD44 expression on benign mucosa. No such association was observed between inflammatory infiltrate and CD44 expression on gastric tumours. CD44 expression, observed in only 49% of primary tumours, was associated with distant metastases at time of diagnosis and, among 31 curatively resected patients, with tumour recurrence (p = 0.0014) and increased mortality (p = 0.001) during follow-up averaging 17 months. When we used an antibody directed against the CD44 variant exon 9v, we found a good correlation between the expression of total CD44 and of exon 9v containing isoforms, and 9v expression in primary tumours was significantly and positively associated with tumour recurrence and mortality.

Adenocarcinoma↗
PubMed1993

Episialin (MUC1) inhibits cytotoxic lymphocyte-target cell interaction.

Episialin (MUC1) is a mucin-like glycoprotein abundantly expressed on most carcinoma cells. As a result of its extended and rigid structure, it reduces intercellular adhesion. We investigated whether this antiadhesion function allows tumor cells expressing high levels of episialin to escape from immune recognition. To test this hypothesis, we transfected episialin-negative (episialin-) melanoma cells (A375) with the MUC1 cDNA-encoding episialin. The results demonstrated that episialin-positive (episialin+) melanoma cells were significantly less susceptible to lysis than episialin- melanoma cells by both alloantigen or rIL-2-stimulated cytotoxic effector cells. In addition, cold target inhibition experiments with episialin+ and episialin- cells clearly demonstrated preferential lysis of episialin- cells. Furthermore, antibody blocking studies showed that lysis of episialin+, but not of episialin-, melanoma cells was predominantly dependent on the leukocyte function-associated Ag-1/intracellular adhesion molecule adhesion route, suggesting that episialin+ target cells adhere less efficiently to effector cells than episialin- target cells. This notion was supported by the observation that conjugate formation of the effector cells with episialin+ target cells was significantly impaired. From these results we conclude that over-expression of episialin as found on many tumor cells may indeed affect efficient lysis by cytotoxic lymphocytes and thus may contribute to escape from immune surveillance.

Antigens, CD↗
PubMed1993

Regulation of integrin-mediated adhesion to laminin and collagen in human melanocytes and in non-metastatic and highly metastatic human melanoma cells.

We compared integrin-mediated adhesion to extracellular matrix (ECM) components of cultured human melanocytes and 6 human melanoma cell lines with different metastatic capacities in nude mice. Cultured melanocytes and most melanoma cell lines adhered strongly to fibronectin (FN), whereas only highly metastatic cell lines adhered to laminin (LM), collagen type I (COI) and type IV (COIV). Adhesion to LM and CO could be blocked by anti-alpha 6 and anti-alpha 2 monoclonal antibodies (MAbs) respectively. This observation is consistent with the finding that expression of LM receptor alpha 6 beta 1 and LM/CO receptor alpha 2 beta 1 was low on melanocytes and non- or poorly metastatic cell lines, whereas these integrins were strongly expressed on highly metastatic cell lines. In addition, immunoprecipitation from [35S]-methionine-labeled cells demonstrated increased synthesis of alpha 6, alpha 2 and beta 1 in highly metastatic cell lines and immunohistochemistry showed expression of alpha 6 beta 1 and alpha 2 beta 1 only in xenograft lesions from highly metastatic cell lines. Furthermore, the observation that adhesion of melanocytes and non- or poorly metastatic cell lines could be stimulated with anti beta 1 MAbs demonstrates that these receptors, on these cells, are expressed in an inactive state. Our results suggest that alpha 2 beta 1 and alpha 6 beta 1 play a role in human melanoma metastasis in nude mice and demonstrate that interactions of these integrins with their ligands can be regulated at the level of surface expression and activation state of the receptor.

Animals↗
PubMed1993

Lymphocyte function-associated antigen 1 dominates very late antigen 4 in binding of activated T cells to endothelium.

Lymphocyte function-associated antigen 1/intercellular adhesion molecule 1 (LFA-1/ICAM-1)-and very late antigen 4/vascular cell adhesion molecule 1 (VLA-4/VCAM-1)-mediated adhesion of T lymphocytes to endothelial cells (EC) can be regulated by increased expression of ICAM-1 and VCAM-1 upon cytokine treatment of EC, or by activation of the integrin molecules LFA-1 and VLA-4 on T cells. Here, we provide evidence that preferential usage of LFA-1 over VLA-4 is yet another mechanism to control T cell adhesion. We observed that binding of activated T lymphocytes, as opposed to resting T cells, to EC is essentially mediated through LFA-1 and not through VLA-4. VLA-4-mediated adhesion of T cells to EC is only found when LFA-1 is not expressed or not functional, as observed for several T cell leukemia cell lines. These results suggest that LFA-1-mediated adhesion dominates and may downregulate VLA-4-mediated adhesion through an unidentified mechanism.

Animals↗
PubMed1993

Role of LFA-1/ICAM-1 in interleukin-2-stimulated lymphocyte proliferation.

Major adhesion routes between lymphoid cells involve the receptor/ligand pairs LFA-1/ICAM-1 and CD2/LFA-3, in addition to VLA or CD44 molecules. In this study we evaluated the role of these adhesion receptors in the proliferative response of lymphoid cells to interleukin-2 (IL-2). Blocking studies were performed with a panel of monoclonal antibodies (mAb) directed against these adhesion molecules. Selective inhibition of recombinant (r)IL-2-induced cell proliferation was observed with mAb directed against the alpha or beta subunit of LFA-1 or to its ligand ICAM-1. Interestingly, rIL-2-induced proliferation was also inhibited by NKI-L16, and anti-1 alpha antibody known to enhance cell-cell interaction. Resting lymphocytes were preferentially susceptible to the inhibition, particularly in an early phase of culture and when stimulated with a relatively low dose of rIL-2. By using mAb that specifically could block distinct rIL-2 activation pathways, LFA-1/ICAM-1 interaction was found to be required for p55 IL-2 receptor (IL-2R)-mediated interaction of rIL-2 with its high-affinity receptor, but not for p75 IL-2R-mediated responses. Furthermore, it was shown that the rIL-2 response of T lymphocytes, but not of natural killer cells, was dependent on LFA-1/ICAM-1 interaction. This suggests that LFA-1/ICAM-1 interaction is required for an optimal rIL-2 response of cells capable of IL-2 secretion. Our data provide evidence for the hypothesis that adhesion receptor-directed release of IL-2 may result in a locally high concentration of IL-2 that triggers high-affinity IL-2R signaling and up-regulates p55 IL-2R to enhance cytokine responsiveness.

Antibodies, Monoclonal↗
PubMed1993

Enhancement of the antibody-dependent cellular cytotoxicity of human peripheral blood lymphocytes with interleukin-2 and interferon alpha.

Antibody-dependent cellular cytotoxicity (ADCC) is regarded as an important mechanism by which monoclonal antibodies (mAb) can exert an antitumour effect in vivo. It may be possible, therefore, to enhance the therapeutic efficacy of mAb by cytokines that are able to enhance the ADCC of human CD3-, CD56+, CD16+ natural killer (NK) cells. We investigated in vitro the effects of recombinant interferon alpha (rIFN alpha) and recombinant interleukin 2 (rIL-2), alone or in combination, on the ADCC of human peripheral blood NK cells. Both cytokines enhanced the ADCC of the human effector cells. rIFN alpha induced a maximally increased ADCC after an exposure of human effector cells to 20 IU/ml for 15-30 min, while rIL-2 induced optimal ADCC after incubation of the cells for 2 days in 20-50 U/ml. We now show that activation of the NK cells with a combination of rIL-2 and rIFN alpha induced significantly higher levels of ADCC than either cytokine alone. The highest ADCC was induced if the cells were first exposed to rIL-2 before rIFN alpha was added to the culture. Culture of NK cells in medium or rIL-2 decreased the expression of Fc gamma RIII (CD16), indicating that intensity of CD16 expression and level of ADCC are not directly correlated, although blocking experiments with a mAb directed against CD16 showed that this Fc gamma R was essential for ADCC of the human effector cells.

Antibodies, Monoclonal↗
PubMed1993

Possible role for cytotoxic lymphocytes in the pathogenesis of acute interstitial nephritis after recombinant interleukin-2 treatment for renal cell cancer.

A patient with renal cell cancer developed acute renal failure due to biopsy-proven acute tubulo-interstitial nephritis (AIN) in the 6th week of continuous infusion of 9 x 10(6) IU m-2 day-1 recombinant interleukin-2 (rIL-2). We investigated whether the AIN was the result of a cellular cytotoxic reaction induced by the rIL-2 treatment. The cytolytic activity of cryopreserved peripheral blood lymphocytes (PBL), isolated before and at the end of the rIL-2 treatment (at the time of AIN), was studied after 5 days of culture with or without rIL-2 or anti-CD28 and immobilized anti-CD3 antibodies. The PBL isolated before and at the end of the rIL-2 treatment showed cytolytic activity towards a number of allogeneic targets. However, only the PBL isolated at the end of the rIL-2 treatment showed, when stimulated with rIL-2 in vitro, significant cytolytic activity against an autologous renal cell line cultured from the AIN biopsy specimen and against an allogeneic renal cell cancer cell line. These PBL displayed no enhanced killing capacity towards autologous PBL and the melanoma cell line M14. These observations suggest that the AIN may be the result of a cytotoxic lymphocyte-mediated reaction induced by the rIL-2 treatment.

Acute Kidney Injury↗
PubMed1993

Immunization with interleukin-2 transfected melanoma cells. A phase I-II study in patients with metastatic melanoma.

The safety, tolerance and clinical effects of immunization with irradiated, allogeneic melanoma cells that express high levels of HLA-A1 and -A2 and secrete IL-2 after transfection with the Interleukin-2 gene, will be assessed in HLA-A1 or HLA-A2 positive melanoma patients with metastatic disease. As a pilot, the first 5-10 patients, if no immediate regression of tumor lesions are observed, will in addition to immunization with these allogeneic tumor cells receive recombinant IL-2 in relatively low doses during three consecutive weeks on an outpatient basis. If no clinical remissions are induced in these first 5-10 patients, subsequent 5-10 patients will receive the same dose of melanoma cells without additional rIL-2. Thereafter the dose of injected melanoma cells will be increased in every following 5-10 patients, but all subsequent patients will receive only IL-2 producing, allogeneic tumor cells, without the addition of rIL-2.

Clinical Protocols↗