Immunogenicity of the ALLAVGATK (gp100[17-25]) peptide in HLA-A3.1 melanoma patients

A T cell line recognizing autologous and allogeneic HLA-A3.1 melanomas was obtained from a disease-free melanoma patient (patient 15392). By transfection of a tumor cDNA library and in vitro sensitization experiments, the ALLAVGATK gp100/Mel17-derived peptide was found to be the epitope recognized by this melanoma-specific T cell line. The role of the ALLAVGATK peptide in the systemic immune response to melanoma of this patient was evaluated. When pulsed on the autologous peripheral blood mononuclear cells, the ALLAVGATK peptide generated tumor-specific HLA-A3-restricted T lymphocytes and a single restimulation in vitro was sufficient to raise gp100-specific T lymphocytes, indicating a high frequency of epitope-specific T cells. gp100-specific T cells were also induced from T lymphocytes purified from tumor-invaded lymph nodes (tumor-associated lymphocytes, TAL). TAL-derived effectors displayed lower peptide affinity and lower tumor recognition than effectors elicited from peripheral blood lymphocytes (PBL). To further evaluate its immunogenicity, ALLAVGATK was used to stimulate PBL derived from six additional HLA-A3.1 melanoma patients and seven healthy donors. After 7 weeks of peptide stimulation in vitro the generation of anti-gp100 and tumor-specific T cell lines was achieved in one out of the six patients analyzed. Taken together these data indicate that an in vivo priming leading to a systemic immunity against gp100 in HLA-A3 melanoma patients may occasionally occur and that the immunogenicity of ALLAVGATK peptide in melanoma patients is comparable to that of other HLA-A2-restricted epitopes derived from gp100/Mel 17 protein.

Melanoma cells constitutively release an anchor-positive soluble form of protectin (sCD59) that retains functional activities in homologous complement-mediated cytotoxicity

Protectin (CD59), a glycosylphosphatidylinositol-anchored cell membrane glycoprotein, is differentially expressed on melanocytic cells and represents the main restriction factor of C-mediated lysis of melanoma cells. In this study, we report that CD59-positive melanoma cells constitutively release a soluble form of CD59 (sCD59), and that its levels directly correlate (r = 0.926; P < 0.05) with the amount of membrane-bound CD59. SDS-PAGE analysis showed that the molecular components of sCD59 are similar to those of cellular CD59 expressed by melanoma cells. Melanoma-released sCD59 is anchor positive since it inserts into cell membranes of homologous cells that transiently increase their expression of CD59. Moreover, sCD59 is functional: it blocks the binding of the anti-CD59 mAb YTH53.1 to melanoma cells and reverses its effects on C-mediated lysis. In fact, preincubation of mAb YTH53.1 with scalar doses of conditioned media of CD59-positive but not of CD59-negative melanoma cells reduced significantly (P < 0.05), and in a dose-dependent fashion, the enhancement of C-mediated lysis of anti-GD3-sensitized melanoma cells induced by the masking of cellular CD59 by mAb YTH53.1. Altogether, these data demonstrate that CD59-positive human melanoma cells release a soluble form of CD59 that is structurally similar to cellular CD59, retains its anchoring ability, is functional, and may impair the effectiveness of clinical approaches to humoral immunotherapy for human melanoma.

Active immunization of metastatic melanoma patients with interleukin-2-transduced allogeneic melanoma cells: evaluation of efficacy and tolerability

From January 1994 to July 1996 we immunized metastatic melanoma patients with HLA-A2-compatible, interleukin-2 (IL-2)-secreting, immunogenic melanoma lines in an attempt to induce a systemic reaction that might also affect distant melanoma lesions. Twelve patients (6 male and 6 female) aged from 28 to 72 years, affected with visceral and/or subcutaneous (s.c.) melanoma metastases, were treated. Two different HLA-A2+ melanoma lines were transduced with the human IL-2 gene (14932/IL-2 and 1B6/IL-2) and used as vaccine. Two groups of 4 patients each were injected s.c. with 5 x 10(7) and 15 x 10(7) irradiated 14932/IL-2 melanoma cells respectively, whereas a third group received 5 x 10(7) cells of the second line (1B6/IL-2). All patients received the vaccine on days 1, 13, 26; if no progression was evident, further immunizations were administered at monthly intervals. All patients were assessable for clinical response after at least three injections of the vaccine. In 4 cases a stabilization of disease lasting from 2 to 6 months was observed: in 2 of them a mixed type of response to treatment was noted with simultaneous evidence of regressing and non-responding lesions in the same patients. No signs of clinical response were found in the remaining patients. Nine patients died of disease between 3 and 24 months after the onset of therapy, whereas 3 were alive 3 months after the end of therapy. The local and systemic side-effects of treatment were mild. These results indicate that vaccination with cells bearing the appropriate antigens and releasing IL-2 locally can produce weak clinical responses, but also indicate that better results may be achieved through modifications of the vaccine, the schedule of immunization and/or a more appropriate selection of patients.

Biphasic control of NF-kappa B activation induced by the triggering of HLA-DR antigens expressed on B cells

The regulation of NF-kappa B activation following the triggering of HLA-DR antigens by mAb L243 has been studied at various times in Raji cells. Electrophoretic mobility shift assays demonstrated a strong increase of NF-kappa B DNA binding after triggering of HLA-DR antigens. Using TNF-alpha-activity neutralizing antibodies, the authors demonstrated that the upregulation of NF-kappa B was found to depend, at later time point, on an autocrine effect of TNF-alpha secreted following triggering of HLA-DR antigens. In contrast, it was found to be TNF-alpha independent in the early time point. Moreover, the upregulation of NF-kappa B binding activity is regulated by the triggering of selected epitopes of HLA-DR antigens. In fact, mAb L243 but not the staphylococcal superantigens, staphylococcal exotoxin toxic shock syndrome toxin-I or staphylococcal enterotoxin B, regulate the NF-kappa B binding activity.

Triggering of HLA-DR antigens differentially modulates tumor necrosis factor alpha release by B cells at distinct stage of maturation

Triggering of HLA class II antigens by the anti-HLA-DR monoclonal antibody (mAb) L243 significantly (P < 0.05) and differentially enhanced the release of tumor necrosis factor alpha (TNF-alpha) by the non-Hodgkin's lymphoma cells Ri-I, Ci-I, and Sc-I, which are at a distinct stage of B-cell differentiation, and by the more mature Burkitt lymphoma cell Raji; in contrast, it did not induce TNF-alpha release by the pre-B leukemia cells Nalm-6 and BV173. TNF-alpha release peaked at 24 h and decreased thereafter, and it was dose dependent and preceded by an increase of TNF-alpha mRNA detectable after 3 h of stimulation with mAb L243. Secreted TNF-alpha mediated the enhancement of nuclear factor kappa B (NF-kappa B) and activator protein-1 (AP-1) binding activity; in fact, the triggering of HLA-DR antigens in the presence of antihuman TNF-alpha-neutralizing antibodies did not upregulate NF-kappa B and AP-1. In contrast, released TNF-alpha was not responsible for the homotypic aggregation of Ri-I, Ci-I, Sc-I, and Raji cells induced by mAb L243, and it did not affect the proliferation of B cells investigated. Altogether, our data demonstrate that: (a) the ability of B cells to release TNF-alpha after triggering of HLA-DR antigens depends on their stage of differentiation; (b) levels of released TNF-alpha seem to correlate with the stage of B-cell maturation but do not correlate with the amounts of cell surface HLA-DR antigens; (c) secreted TNF-alpha regulates the levels of expression of NF-kappa B and AP-1 by an autocrine loop; and (d) intracellular signals mediating TNF-alpha release by B cells are distinct from those regulating homotypic aggregation and proliferation.

Tumour-derived interleukin 1alpha (IL-1alpha) up-regulates the release of soluble intercellular adhesion molecule-1 (sICAM-1) by endothelial cells

Levels of circulating soluble intercellular adhesion molecule-1 (sICAM-1) are elevated in patients affected by solid malignancies; however, the cellular sources generating high levels of sICAM-1 remain to be characterized. Using conditioned media (CM) from seven ICAM-1-positive or -negative neoplastic cells, we demonstrate that tumour-derived interleukin 1alpha (IL-1alpha) significantly (P < 0.05) up-regulates the release of sICAM-1 by human umbilical vein endothelial cells. The intensity of the effect correlated with the amounts of IL-1alpha detectable in CM. Levels of ICAM-1 mRNA were also up-regulated by tumour-secreted IL-1alpha. The up-regulation of the shedding of sICAM-1 and of its expression at protein and mRNA level were completely reversed by the addition of anti-IL-1alpha neutralizing antibodies. Consistent with the in vitro data, tumour endothelia were strongly stained for ICAM-1 compared with autologous normal tissue endothelia. Taken altogether, our observations reveal an IL-1alpha-mediated tumour-endothelium relationship sustaining the shedding of sICAM-1 by endothelial cells. This is a general phenomenon in solid malignancies that correlates with the ability of neoplastic cells to secrete IL-1alpha rather than with their expression of ICAM-1 and/or histological origin. sICAM-1 has been previously shown to inhibit LFA-1/ICAM-1-mediated cell-cell interactions; therefore, the ability of neoplastic cells to secrete IL-1alpha is likely to represent a mechanism for their escape from immune interaction.

Melanoma-associated hypopigmentation: where are the antibodies?

Antibodies to the B16 melanoma cell line and to tyrosinase have been recently defined in our laboratory in sera of patients with vitiligo, melanoma, melanoma-associated hypopigmentation (MAH), and in healthy subjects. The antibody titers in each subject were measured by enzyme-linked immunosorbent assay, were compared with the mean optical density (OD) of the control group, and were expressed as relative OD. The titers of anti-B16 antibodies (relative OD +/- standard error) were 1.000 (0.058) in the controls, 1.025 (0.077) in patients with metastatic melanoma, 0.5862 (0.15) in MAH, 1.377 in surgery-induced MAH, 1.087 in vaccination with anti-idiotypic antibodies, and 2.098 (0.15) in autoimmune vitiligo. The titers in vitiligo were significantly higher (p < 0.0001) than in MAH or in healthy controls. Antityrosinase antibodies were found in titers of 1.000 (0.1024) in the controls, 1.516 (0.225) in metastatic melanoma, 1.027 (0.180) in MAH, 1.075 in surgery-induced MAH, 2.308 in vaccination-induced MAH, and 4.536 in vitiligo. Differences were found between vitiligo and MAH (p = 0.008), surgery-induced MAH (p = 0.009), vaccination-induced MAH (p = 0.059), and healthy subjects (p < 0.0001). The results of this study point to the cross-antigenicity between melanocytes and melanoma cells, and to participation of antibodies against melanoma-associated membrane antigens in the mechanism leading to the development of MAH in patients with melanoma.

Expression and structural features of endoglin (CD105), a transforming growth factor beta1 and beta3 binding protein, in human melanoma

Human endoglin (CD105) is a member of the transforming growth factor beta (TGF-beta) receptor family that binds TGF-beta1 and -beta3, but not TGF-beta2, on human endothelial cells. Immunohistochemical analyses demonstrated that CD105 is expressed on normal and neoplastic cells of the melanocytic lineage. The anti-CD105 MAb, MAEND3, stained 50, 25 and 34% of intradermal naevi, primary and metastatic melanomas investigated, respectively, and nine out of 12 melanoma cell lines. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis revealed that CD105 expressed by melanoma cells consists of a homodimeric protein with an apparent molecular weight of 180 and 95 kDa under non-reducing and reducing conditions. Cross-linking of 125I-labelled TGF-beta1 to melanoma cells, Mel 97, by disuccinimidyl suberate (DSS) demonstrated that CD105 expressed on pigmented cells binds TGF-beta1; the pattern of binding of TGF-beta1 to melanoma cells was found to be similar to that of human umbilical vein endothelial cells. The addition of exogenous, bioactive TGF-beta1 significantly (P<0.05) inhibited the growth of CD105-positive melanoma cells, Mel 97, but did not affect that of CD105-negative melanoma cells, F0-1. These data, altogether, demonstrate that CD105 is expressed on pigmented cells and might play a functionally relevant role in the biology of human melanoma cells by regulating their sensitivity to TGF-betas.

Limited antitumor T cell response in melanoma patients vaccinated with interleukin-2 gene-transduced allogeneic melanoma cells

We have immunized advanced melanoma patients with a HLA-A2-compatible human melanoma line genetically modified to release interleukin-2 (IL-2), to elicit or increase a T cell-mediated anti-melanoma response that may affect distant lesions. Twelve stage-IV patients were injected subcutaneously at days 1, 13, 26, and 55 with IL-2 gene-transduced and irradiated melanoma cells at doses of 5 or 15 x 10(7) cells. Both local and systemic toxicities were mild, consisting of transient erythema at the vaccination site; fever occurred in a minority of patients. Three mixed responses were recorded. Seven patients were evaluable for immunological studies. Mixed tumor-lymphocyte cultures carried out with different allogeneic HLA-A2-matched melanoma lines as stimulators and targets revealed an increase in the MHC-unrestricted, but no changes in the MHC-restricted, cytotoxicity in peripheral blood lymphocytes (PBL) obtained after vaccination as compared with those obtained before vaccination. Increased recognition of the tyrosinase 368-376 peptide occurred in post-vaccination PBL of one patient, whereas a weak increase in recognition of the gp100 280-288 peptide was detectable in another patient; these 2 patients also recognized the gp100 457-466 peptide. After in vitro, stimulation with the only available autologous melanoma line, CD4+ cells with autologous tumor-specific cytotoxicity and ability to release interferon-gamma (IFN-gamma) were found in post- but not in pre-vaccination PBL. In the same patient, as well as in another patient, limiting dilution analysis showed that vaccination resulted in an increased frequency of melanoma-specific cytotoxic T lymphocyte (CTL) precursors. These results indicate that vaccination with cells releasing IL-2 locally can expand a T cell response against antigen(s) of autologous, untransduced tumor, although this response occurred in a minority of the melanoma patients studied.

The vitronectin receptor alpha-V beta-3, contrary to ICAM-1, is not modulated by interferon-gamma and tumour necrosis factor-alpha on melanoma cell lines

A correlation was recently shown between expression of the vitronectin receptor (VnR) and the tumorigenic capacity of cultured human melanoma cell lines. On the other hand, modulation of VnR expression by interferon-gamma (IFN-gamma) and tumour necrosis factor-alpha (TNF-alpha) was observed on different non-melanoma cell lines. We tested IFN-gamma, TNF-alpha and interleukin-2 (IL-2), which are presumably released by infiltrating leukocytes in the melanoma lesional environment, on three melanoma cell lines. The VnR expression was assessed using FACS analysis and radioimmunolabelling. The VnR did not show any modulation after treatment with any of the cytokines tested. By contrast, the expression of the intercellular adhesion molecule-1 (ICAM-1), tested as control, on five melanoma cell lines, was greatly enhanced by IFN-gamma and TNF-alpha. Thus, some host cytokines may preferentially induce melanoma cells to express ICAM-1 (which can increase host cytotoxic response against melanoma), other than the VnR (which instead might contribute to melanoma metastasis).

Triggering of target of an antiproliferative antibody-1 (TAPA-1/CD81) up-regulates the release of tumour necrosis factor-alpha by the EBV-B lymphoblastoid cell line JY

Target of an antiproliferative antibody-1 (TAPA-1/CD81) has been shown to be non-covalently associated to HLA-DR antigens on the cell surface of B cells. In this study the authors report that triggering of CD81 by MoAb 5A6 or 1D6 significantly (P < 0.05) up-regulates the release of tumour necrosis factor-alpha (TNF-alpha) by the Epstein-Barr virus-positive (EBV)-B lymphoblastoid cell line JY. The accumulation of TNF-alpha in the culture medium of JY cells incubated with either anti-CD81 MoAb was found to be dose-dependent and similar to that obtained following crosslinking of HLA-DR antigens with MoAb L243. The effect of the combination of anti-CD81 and anti-HLA-DR MoAb on the release of TNF-alpha by JY cells was not synergistic or additive. In addition, the combination of anti-CD81 and anti-HLA-DR MoAb did not affect proliferation and homotypic aggregation of JY cells induced by each MoAb used alone. Both anti-CD81 or anti-HLA-DR MoAb induced protein tyrosine phosphorylation. However, different cytoplasmic proteins were phosphorylated following triggering of either molecule. Taken together, the data demonstrate that CD81 and HLA-DR antigens induce similar effector phenomena in the regulation of TNF-alpha release, homotypic aggregation and inhibition of JY cell proliferation.

Levels of cell membrane CD59 regulate the extent of complement-mediated lysis of human melanoma cells

Normal and neoplastic cells are protected from autologous complement (C) attack by different cell-surface C-regulatory proteins including CD59 (protectin), CD46 (membrane cofactor protein) and CD55 (decay-accelerating factor). Indirect immunofluorescence (IIF) analysis showed a differential expression of CD59, CD46, and CD55 in nine human melanoma cell lines and that the expression of CD59 was highly heterogeneous compared with that of CD46 and CD55. Levels of cell membrane CD59 were found to regulate the differential sensitivity of melanoma cells investigated to homologous C-mediated lysis; in fact, an inverse correlation (r > 0.7, p < 0.05) was found between levels of cell membrane CD59, but not of CD46 and CD55, and extent of C-mediated lysis of melanoma cells sensitized with scalar concentrations of the anti-GD3 ganglioside mAb R24. Masking of CD59 by 2.5 micrograms/ml of the anti-CD59 mAb YTH53.1 induced or enhanced C-mediated lysis of melanoma cells sensitized with 2.5 micrograms/ml of mAb R24; the latter phenomenon was found to be directly correlated (r > 0.865, p < 0.01) with levels of cell membrane CD59. CD59 is bound to melanoma cells by a glycosylphosphatidylinositol anchor: treatment of C-resistant melanoma cells Mel 97, by increasing doses of phosphatidylinositol-specific phospholipase C (PI-PLC), progressively decreased cell-surface expression of CD59 and increased C-mediated lysis of cells sensitized with mAb R24. Staining of 38 benign and malignant lesions of melanocytic origin by mAb YTH53.1 demonstrated that CD59 is consistently expressed in vivo and confirmed the heterogeneous expression detected in vitro. Our data, altogether, demonstrate that CD59 is the main restriction factor of C-mediated lysis of melanoma cells and that levels of CD59 may account for their differential resistance to C-mediated lysis. The analysis of the levels of CD59 could represent an useful strategy in selecting melanoma patients who may benefit from immunotherapeutic treatment(s) that trigger C activation.

Anti-tyrosinase antibodies participate in the immune response to vaccination with anti-idiotypic antibodies mimicking the high-molecular-weight melanoma-associated antigen

Seven patients with metastatic melanoma were vaccinated with anti-idiotypic monoclonal antibody (mAb) MK2-23 which mimics the high-molecular-weight melanoma-associated antigen (HMW MAA). Sera samples were assayed for anti-anti-idiotypic antibodies, by Ab1-Ab2 complex inhibition test, for anti-B16 epitope antibodies, which are a heterogeneous group against various antigens presented on B16 melanoma cells and for anti-tyrosinase antibodies, which are specific against tyrosinase. Our results pointed to the participation of anti-tyrosinase antibodies in the immune response to vaccination by anti-idiotypic antibodies mimicking the HMW MAA. The anti-tyrosinase antibody kinetic curves presented an initial increase in titres in five cases followed by decreasing titres; in two cases a constant decrease was noted. The inhibition assay demonstrated an increasing percentage of inhibition (range 17-100%) within 100-400 days of treatment. The titre of the anti-tyrosinase antibodies increased following the vaccination, then decreased--probably due to absorption of the antibodies to melanoma cells and normal melanocytes. A positive slope in the percentage of inhibition was roughly associated with a negative slope of anti-tyrosinase antibodies. In one case, a long-standing complete clinical response was accompanied by development of melanoma-associated hypopigmentation. Anti-B16 epitope antibodies had no role in the response to vaccination. The development of anti-tyrosinase antibodies in response to vaccination by anti-idiotypic antibodies mimicking another antigen may be explained by induction of non-specific polyclonal B lymphocytes activation, a well-recognized phenomenon in autoimmune disorders.(ABSTRACT TRUNCATED AT 250 WORDS)

[Changes in immune status due to anesthesia and surgical intervention. The role of thymopentin and interleukins]

OBJECTIVE

Purpose of the study was clinical evaluation of thymopentin and interleukins in the changes of immunity due to anesthesia and surgical operation.

DESIGN

After randomization the patients were divided into four groups according to starter type (thiopental or propofol) and immunological pre-treatment (tymopentin or saline of control group) administered for three days before and two days after operation.

SETTING AND PATIENTS

The study was effected on 40 patients undergoing venous vascular surgery in operating rooms of Medical School of University of Genoa.

MEASUREMENT

At pre-established times (basal, before and after induction, recovery and 72 postoperative hours) were measured some immunological data (plasmatic concentrations of red blood cells, white blood cells, lymphocyte cells, antibodies, complement analysis, interleukins 1 and 2).

RESULTS

The results show a depression of immunity with hypoleucocistosis and hyperlymphocytosis due to surgical trauma or to anesthesia drugs.

CONCLUSIONS

Pre-treatment with thymopentin no change perioperative immunity and the role of interleukins isn't clear; the immunological depression is the same in thiopental of propofol groups.

Cross-linking of HLA class II antigens modulates the release of tumor necrosis factor-alpha by the EBV-B lymphoblastoid cell line JY

In addition to their functional role as peptide-binding proteins HLA class II Ag can also act as signal-transducing molecules. The present study showed that cross-linking of HLA class II Ag by the anti-HLA-DR mAb L243 or by the anti-HLA-DR,-DP mAb IVA12 significantly (p &lt; 0.05) increased the release of TNF-alpha by the EBV-B lymphoblastoid cell line JY. In contrast, the anti-HLA-DR mAb 2.06 or the superantigens staphylococcal exotoxin toxic shock syndrome toxin-1 and staphylococcal enterotoxin B that bind to HLA-DR,-DQ Ag did not affect the release of TNF-alpha by JY cells. The accumulation of TNF-alpha in the culture medium of JY cells peaked at 24 h, decreased thereafter, and was found to be dependent on the dose of mAb L243 or mAb IVA12 used to cross-link HLA class II Ag. mAb L243 or staphylococcal exotoxin toxic shock syndrome toxin-1 enhanced the spontaneous homotypic aggregation of JY cells and mediated a dose-dependent inhibition of JY cell proliferation. These phenomena were not mediated by TNF-alpha released in response to cross-linking of HLA class II Ag; polyclonal anti-TNF-alpha neutralizing antibody did not affect JY cell aggregation and the inhibition of JY cell proliferation mediated by mAb L243. In contrast, TNF-alpha secreted by JY cells enhanced a nuclear factor-kB-like activity through the binding to the 75-kDa TNF-alpha receptor. These results demonstrate an additional role of HLA class II Ag as signal-transducing molecules regulating the production of bioactive TNF-alpha by EBV-B cells. The release of TNF-alpha after the triggering of HLA class II molecules could be relevant to different aspects of B cell biology and might play a role in the pathogenesis of human diseases in which antibodies cross-reactive to HLA class II Ag have been identified.

Cross-linking of HLA class II antigens modulates the release of tumor necrosis factor-alpha by the EBV-B lymphoblastoid cell line JY

In addition to their functional role as peptide-binding proteins HLA class II Ag can also act as signal-transducing molecules. The present study showed that cross-linking of HLA class II Ag by the anti-HLA-DR mAb L243 or by the anti-HLA-DR,-DP mAb IVA12 significantly (p < 0.05) increased the release of TNF-alpha by the EBV-B lymphoblastoid cell line JY. In contrast, the anti-HLA-DR mAb 2.06 or the superantigens staphylococcal exotoxin toxic shock syndrome toxin-1 and staphylococcal enterotoxin B that bind to HLA-DR,-DQ Ag did not affect the release of TNF-alpha by JY cells. The accumulation of TNF-alpha in the culture medium of JY cells peaked at 24 h, decreased thereafter, and was found to be dependent on the dose of mAb L243 or mAb IVA12 used to cross-link HLA class II Ag. mAb L243 or staphylococcal exotoxin toxic shock syndrome toxin-1 enhanced the spontaneous homotypic aggregation of JY cells and mediated a dose-dependent inhibition of JY cell proliferation. These phenomena were not mediated by TNF-alpha released in response to cross-linking of HLA class II Ag; polyclonal anti-TNF-alpha neutralizing antibody did not affect JY cell aggregation and the inhibition of JY cell proliferation mediated by mAb L243. In contrast, TNF-alpha secreted by JY cells enhanced a nuclear factor-kB-like activity through the binding to the 75-kDa TNF-alpha receptor. These results demonstrate an additional role of HLA class II Ag as signal-transducing molecules regulating the production of bioactive TNF-alpha by EBV-B cells. The release of TNF-alpha after the triggering of HLA class II molecules could be relevant to different aspects of B cell biology and might play a role in the pathogenesis of human diseases in which antibodies cross-reactive to HLA class II Ag have been identified.

Differential expression of cell adhesion molecules CD54/CD11a and CD58/CD2 by human melanoma cells and functional role in their interaction with cytotoxic cells

Immunohistochemical staining with monoclonal antibodies showed a differential distribution of intercellular adhesion molecule 1 (ICAM-1/CD54) and lymphocyte function-associated antigen 3 (LFA-3/CD58) and their respective counterreceptors lymphocyte function-associated antigens 1 (LFA-1/CD11a) and 2 (LFA-2/CD2) on ten melanoma cell lines and in 46 surgically removed metastatic melanoma lesions. CD11a and CD2 were not detected on melanoma cells while CD54 and CD58 were coexpressed on the majority of the melanoma cell populations investigated. CD54 showed a higher degree of intra- and intertumor heterogeneity than CD58. gamma-Interferon and/or tumor necrosis factor alpha upregulated the expression of CD54 by melanoma cells, but neither modulated that of CD58 nor induced that of CD11a and CD2. Anti-CD54 and anti-CD58 monoclonal antibodies partially inhibited the lysis of melanoma cells by allogeneic natural killer cells, lymphokine-activated killer cells and, to a greater extent, by autologous tumor-infiltrating lymphocytes. Soluble CD54 (cCD54) purified from serum of patients with melanoma inhibited the lysis of melanoma cells F0-1 by natural killer cells in a dose-dependent fashion. These results suggest that membrane-bound CD54 and CD58 and cCD54 play a role in host-tumor interactions in patients with malignant melanoma and may account for the relationship between CD54 expression in primary lesions and the clinical course of disease.

Reduction in susceptibility to natural killer cell-mediated lysis of human FO-1 melanoma cells after induction of HLA class I antigen expression by transfection with B2m gene

Induction of HLA class I antigens on cultured melanoma cells FO-1 after transfection with a human or a mouse B2m gene was associated with a statistically significant reduction in their susceptibility to natural killer (NK) cell-mediated lysis. These results indicate that the structural differences between human and mouse beta 2-mu do not abolish the ability of the HLA class I molecular complex to modulate NK cell-mediated lysis of melanoma cells FO-1. The role of HLA class I antigens in the phenomenon is corroborated by the ability of anti-HLA class I MAb to enhance, although to a different extent, the susceptibility of transfected FO-1 cells to NK cell-mediated lysis. Gamma interferon (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) significantly reduced the susceptibility to NK cell-mediated lysis of transfected FO-1 cells. Surprisingly, TNF-alpha reduced the extent of lysis more than IFN-gamma, although the latter cytokine enhanced HLA class I antigen expression more than the former one. This finding, in conjunction with a reduction in the susceptibility to NK cell-mediated lysis of untransfected FO-1 cells incubated with IFN-gamma or TNF-alpha, suggests that the two cytokines reduce NK cell-mediated lysis of transfected cells by modulating not only the expression of HLA class I antigens, but also that of other structures. Induction of HLA class I antigens and their modulation with IFN-gamma did not affect the susceptibility to lymphokine-activated killer (LAK) cell-mediated lysis of transfected FO-1 cells. Characterization of the molecular mechanism(s) underlying abnormalities in HLA class I antigen expression by melanoma cells and of the role of these molecules in the interactions of melanoma cells with various types of effector cells may suggest novel immunotherapeutic approaches to melanoma.

Differential expression of CD54/intercellular adhesion molecule-1 in myeloid leukemias and in lymphoproliferative disorders

Indirect immunofluorescence staining with monoclonal antibody (MoAb) CL203.4 of malignant cells from 269 patients with hematologic malignancies showed a heterogeneous expression of CD54/intercellular adhesion molecule-1 (ICAM-1). This marker was expressed by malignant cells of 57 out of 118 patients with myeloid malignancies and 69 out of 135 with B-lymphoid malignancies. On the other hand, CD54 was not detected on malignant cells of 16 patients with T-lymphoid malignancies. In myeloid malignancies, CD54 is preferentially expressed by "stem cell-derived" malignancies, being detectable on blast cells from almost all patients affected by chronic myelogenous leukemia in blast phase or myelodysplastic syndromes and by only 34% of patients with de novo acute myeloid leukemia (AML). The expression of CD54 did not correlate with any specific myeloid FAB subtype, although three cases of highly undifferentiated AML (FAB MO) displayed maximal levels of the antigen. The expression of CD54 in AML was significantly associated with that of CD34 and HLA-DR antigens. In B-lymphoid malignancies, CD54 expression appears to correlate with the differentiation stage of malignant cells, since B-origin acute lymphoblastic leukemias and conventional B-chronic lymphocytic leukemias (B-CLL; ie, "dim SIg" CLL) expressed lower levels of CD54 than more mature lymphoproliferative disorders ("bright SIg" CLL, prolymphocytic leukemias, and lymphoplasmacytic tumors). "High-grade" B-cell non-Hodgkin's lymphomas (B-NHL) express in general a higher level of CD54 than "low-grade" ones. This finding in conjunction with the expression of CD54 in all 17 patients with "bright SIg" CLL investigated (characterized by marked organomegaly and poor prognosis) suggest that the differential expression of CD54 in lymphoproliferative disorders may also relate to their degree of malignancy.