Baseline neutrophils and derived neutrophil-to-lymphocyte ratio: prognostic relevance in metastatic melanoma patients receiving ipilimumab.

BACKGROUND: Clinical responses to ipilimumab are variable in terms of onset, magnitude and duration. Upfront identification of patients who are more likely or unlikely to benefit from treatment is a major need. PATIENTS AND METHODS: Prospectively collected data from 720 advanced melanoma patients treated with ipilimumab 3 mg/kg within the Italian expanded access program were analyzed. The derived neutrophil-to-lymphocyte ratio (dNLR) was calculated from baseline peripheral blood cell counts, and receiver operating characteristic curve was used to evaluate the best cutoff for this marker. Patients were stratified according to dichotomized baseline absolute neutrophil counts (ANC), dNLR and their combination. The prognostic values of ANC and dNLR for survival were assessed using multivariate Cox proportional hazard models. A subgroup analysis including LDH in the models was also carried out. RESULTS: The median follow-up was 16.5 months. The optimal cutoff for dNLR was 3. Baseline ANC and dNLR were significantly associated with the outcome of ipilimumab-treated melanoma patients, in terms of disease progression and death (P < 0.0001 for all). Furthermore, for each elevated variable, prognosis worsened. Patients with both ANC ≥ 7500 and dNLR ≥ 3 had a significantly and independently increased risk of death [hazard ratio(HR) = 5.76; 95% confidence interval (CI) 4.29-7.75] and of progression (HR = 4.10; 95% CI 3.08-5.46) compared with patients with both lower ANC and dNLR. Patients with one of the two factors elevated displayed an intermediate risk of progression and death. The 1- and 2-year survival rates were 2% and 0%, respectively, for patients with ANC ≥ 7500 and dNLR ≥ 3, and 43% and 24%, respectively, for patients with both lower ANC and dNLR. CONCLUSIONS: Although these findings need to be confirmed and validated, we suggest that a neutrophil-based index may help risk-group stratification and assist disease-management strategies. Furthermore, the potential predictive value of this index for response to ipilimumab should be investigated in randomized clinical trials.

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.

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.

Primary hepatic epithelioid hemangioendothelioma progressively responsive to interferon-alpha: is there room for novel anti-angiogenetic treatments?

Primary hepatic epithelioid hemangioendothelioma (HEH) is a rare, low-grade malignant neoplasm of endothelial origin, with an unpredictable clinical course and prognosis. No standard therapeutic strategies are still available for HEH, due to the infrequency of the disease and to its variable natural history that limit the identification of the most effective treatment. In the absence of metastatic disease, surgical resection or liver transplantation represent the treatment of choice for HEH, while several antineoplastic agents have been proposed in the presence of metastatic nonresectable disesase. Herein, we describe the biological characterization and the clinical course of a primary HEH progressively responsive to treatment with intermediate doses of interferon-alpha (IFN)-alpha2a. Furthermore, based on the newly-identified expression of endoglin (CD105) on HEH, we discuss the clinical potential of novel anti-angiogenetic approaches to the disease.

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.

Endoglin is a suitable target for efficient imaging of solid tumors: in vivo evidence in a canine mammary carcinoma model.

Increasing evidence suggests that endoglin (CD105) is a new powerful marker of neovascularization in solid malignancies; thus, using breast cancer as a model, we investigated whether targeting of CD105 by monoclonal antibody (mAb) MAEND3 can be used for in vivo imaging of solid tumors. Immunohistochemistry and flow cytometry identified differential expression of CD105 on breast cancer and endothelial cells; in fact, neoplastic cells were weakly and rarely stained by mAb MAEND3, which in contrast, strongly and invariably stained blood vessel endothelia within the breast adenocarcinomas investigated and cultured endothelial cells. Moreover, in contrast to CD31, which currently represents the reference marker to assess angiogenetic activity, CD105 expression was highest in semiconfluent and actively proliferating endothelial cells, and it progressively decreased as cells reached tight confluency and low [3H]thymidine uptake. i.v. administration of 18 MBq of 125I-labeled mAb MAEND3 efficiently imaged spontaneous mammary adenocarcinomas in two dogs; the uptake of radiolabeled mAb was rapid and intense because tumor: background ratios of 8.2:1 and 9.3:1 were reached 8 h after mAb administration, in the absence of immediate and/or long-term clinical side effects. Altogether, our present data suggest that targeting of CD105 on tumor-associated blood vessels may represent a new strategy for in vivo imaging of solid malignancies, regardless of their histological origin.

Emerging role of endoglin (CD105) as a marker of angiogenesis with clinical potential in human malignancies.

Angiogenesis is crucial for tumor development and progression, and antiangiogenetic therapy represents a promising approach for cancer treatment. Thus, the in-depth understanding of the molecular mechanism(s) regulating angiogenesis, together with the characterization of molecules expressed by endothelial cells and involved in distinct steps of the angiogenetic process, will greatly improve the design of new and more effective therapeutic strategies in human malignancies. Endoglin (CD105), a cell membrane glycoprotein predominantly expressed on cellular lineages within the vascular system, and over-expressed on proliferating endothelial cells, is involved in blood vessels development and represents a powerful marker of neovascularization. CD105 binds several factors of the Transforming Growth Factor (TGF)-beta superfamily, a pleiotropic cytokine that regulates different cellular functions including proliferation, differentiation and migration. In human malignancies of different histotype, CD105 is highly expressed on endothelial cells of both peri- and intra-tumoral blood vessels, while it is weakly expressed or absent on neoplastic cells. This unique tissue distribution strongly suggests for a prognostic, diagnostic and therapeutic potential of CD105 in neoplastic diseases. In this review we will summarize the structural and functional features of CD105, as well as its tissue distribution in normal and neoplastic tissues. Furthermore, the practical implications of CD105 in human malignancies will also be discussed.

Bioimmunotherapeutic targets on angiogenetic blood vessels in solid malignangies.

Physiological angiogenesis is a tightly regulated process that occurs mainly during reproduction, development and wound healing. Although angiogenesis is a continuous process, different consecutive steps can be identified, including: i) release of pro-angiogenetic factors; ii) release of proteolytic enzymes; iii) endothelial cell migration, morphogenesis and proliferation. Angiogenesis is also a hallmark of malignant diseases, and an inverse correlation between tumor vascularity and survival was demonstrated. Thus, strategies aimed at interfering with tumor blood supply by targeting tumor vasculature, presently represent promising new approaches for the treatment of solid malignancies. In fact, at least 30 angiogenetic inhibitors, utilized alone or in combination with other therapeutic agents, are currently being tested in clinical trials in humans. In this paper, we will review current knowledges on selected molecules expressed by endothelial cells and involved in distinct steps of the angiogenetic process, that represent potential targets for bioimmunotherapeutic approaches in human malignancies.

Endoglin (CD105): a target for anti-angiogenetic cancer therapy.

Targeting of tumor vasculature is a promising strategy for cancer treatment. Among endothelial cell markers, Endoglin, a cell membrane glycoprotein, is emerging as an attractive therapeutic target on angiogenetic blood vessels, and it currently represents a powerful marker to quantify tumor angiogenesis. In normal human tissues, Endoglin is weakly expressed on erytroid precursors, stromal cells and activated monocytes, whereas it is strongly expressed on proliferating endothelial cells. In human neoplasias of different histotype, Endoglin is mainly present on endothelial cells of both peri- and intra-tumoral blood vessels, while it is weakly expressed or absent on neoplastic cells. Endoglin is an accessory component of the receptor complex of Transforming Growth Factor (TGF)-beta, a pleiotropic cytokine that modulates angiogenesis by the regulation of different cellular functions including proliferation, differentiation and migration. Interestingly, the over-expression of Endoglin antagonizes several cellular responses to TGF-beta1, while its down-regulation potentiates cellular responses to TGF-beta1. In animal models, administration of radiolabeled anti-Endoglin monoclonal antibodies (mAb) efficiently images primary tumors, and naked or conjugated anti-Endoglin mAb suppress angiogenesis and tumor growth. In this review we will summarize the complex of experimental evidences pointing to Endoglin as a vascular target to design innovative bioimmunotherapeutic strategies in human neoplasias.

Structure, distribution, and functional role of protectin (CD59) in complement-susceptibility and in immunotherapy of human malignancies (Review).

Protectin (CD59) is a glycosyl-phosphatidylinositol-anchored cell membrane glycoprotein, ubiquitously expressed, though to a different extent, on benign and malignant cells. CD59 inhibits complement (C)-mediated lysis of target cells by preventing the formation of the membrane attack complex, in the terminal step of C-activation. Recent experimental evidence demonstrates that CD59 is the main restriction factor of C-mediated lysis of malignant cells of different histotype. Additionally, a soluble form of CD59, that retains its anchoring ability and functional properties, has been most recently identified in body fluids and in culture supernatants of different malignant cells. In view of its functional role, CD59 may protect neoplastic cells from C-mediated lysis, contributing to their escape from innate C-control and to tumor progression; additionally, the expression of CD59 by neoplastic cells may contribute to impair the therapeutic efficacy of C-activating monoclonal antibodies (mAb) directed to tumor-associated antigens. In the light of the functional role of CD59, this review focuses on the structural features, tissue distribution and regulation of the expression of CD59 in malignant tissues, and on the foreseeable application(s) of CD59 to improve the therapeutic efficacy of clinical approaches of humoral immunotherapy with C-activating mAb in human malignancies.

Intercellular adhesion molecule-1 is upregulated via the protein kinase C pathway in human thyroid carcinoma cell lines.

Nonantigen specific adhesion systems lymphocyte function-associated antigen 1/intercellular adhesion molecule (LFA-1/ICAM-1) and cluster designation 2/lymphocyte function-associated antigen 3 (CD2/LFA-3) are considered a crucial step in immune-mediated cell-cell adhesion reactions. In particular, the LFA-1/ICAM-1 system is deeply involved in major histocompatibility system (MHC)-restricted and non-MHC-restricted cellular cytotoxicity of effector cells against cancer tissues. We have investigated in human thyroid carcinoma cell lines the role of the protein kinase C (PKC) pathway on ICAM-1 expression. Incubation with tissue plasminogen activator (TPA), an agonist of PKC, of two papillary (NPA and TPC-1) and one anaplastic (ARO) carcinoma cell lines induced an ICAM-1 upregulation of both protein and mRNA production. This phenomenon was dependent on RNA and protein synthesis and was inhibited by PKC antagonists such as staurosporine and H-7. A parallel increase in the soluble form of ICAM-1 followed the upregulation of cellular ICAM-1 levels induced by TPA. In conclusion, the PKC pathway is involved in the regulation of ICAM-1 expression in human thyroid carcinoma cell lines. Further studies are necessary to clarify the effects of the PKC pathway on the diffusion of thyroid tumors.

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)

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.

Lateral ventricle subependymomas. Case report taking into particular consideration the aspects of magnetic resonance and review of the literature.

Subependymomas are rare neuroectodermic tumours. The authors report a case of a patient he had a subendymoma in the left lateral ventricle, with particular attention to the MR aspects on these lesions and review of the literature.

Emerging role of protectin (CD59) in humoral immunotherapy of solid malignancies.

Over the past two decades, complement (C)-activating monoclonal antibodies (mAb), directed to specific tumor-associated antigens (TAA), have been extensively utilized for passive immunotherapy of solid tumors of different histology. However, the clinical outcome of this therapeutic approach has been substantially disappointing; antigenic heterogeneity of neoplastic cells and their limited accessibility by therapeutic mAb, have been provided as substantial explanations for the poor clinical results obtained. Nevertheless, in light of the recent advances in the knowledge of the mechanisms regulating C-activity, it begins to be evident that membrane and soluble C-inhibitory proteins play a key role in the protection of neoplastic cells from C-attack, providing additional insights on biological features of transformed cells that may hamper the clinical efficacy of humoral immunotherapy. Among C-regulatory proteins investigated, this review will focus on protectin (CD59) that represents the main restriction factor of C-susceptibility of neoplastic cells from solid malignancies. In view of the functional role of CD59, we will describe its tissue distribution and biological features in malignant neoplasms; major emphasis will be given to cutaneous melanoma, in which the C-regulatory role of CD59 has been extensively investigated, and clinical approaches of humoral immunotherapy have been implemented. According to the available data, the foreseeable strategies to improve the therapeutic efficacy of humoral immunotherapy of solid malignancies will be discussed.

Intracranial haemorrhage in patients on antithrombotics: clinical presentation and determinants of outcome in a prospective multicentric study in Italian emergency departments.

BACKGROUND: Intracranial haemorrhage (ICH) is the type of stroke associated with the highest death rate, and about 30% of ICH occurs in patients on antithrombotic treatment. This study relates clinical presentations and outcome of ICH patients on oral anticoagulant (OA) or antiplatelet (AP) therapy admitted to 33 Italian emergency departments (ED). METHODS: Consecutive patients were enrolled after cranial computed tomography (CT). Primary outcome was the Modified Rankin Scale (MRS) score at 3 months of follow-up. Common descriptive statistics were computed after stratification for traumatic or spontaneous ICH and identification of the anatomical location of bleeding. Multivariate logistic regression was used to assess predictors of death. RESULTS: We recruited 434 patients on AP therapy and 232 on OA. There were 432 spontaneous and 234 traumatic ICH patients. The proportions of AP and OA patients undergoing neurosurgery were 21.8 and 19.4%, respectively, while < 30% underwent procoagulant medical treatment. At the 3-month follow-up, the case fatality rate was 42.0%, while disability or death (MRS 3-6) was 68.1%. The odds ratio for death in OA versus AP patients was 2.63 (95% CI 1.73-4.00) in the whole population and 2.80 (95% CI 1.77-4.41) in intraparenchymal event patients. Glasgow Coma Scale, age, spontaneous event and anticoagulant use were found to be predictors of death both in traumatic and spontaneous events. CONCLUSION: This study confirms the high prevalence of death or disability in OA and AP patients with ICH. As far as the determinants of mortality and disability are concerned, the results of this study might be useful in the clinical management and allocation of resources in the ED setting. The observed low use of procoagulant therapy highlights the need for ED educational programmes to heighten the awareness of available and effective haemostatic treatments.

The overlooked "nonclassical" functions of major histocompatibility complex (MHC) class II antigens in immune and nonimmune cells.

Besides their "classical" antigenic peptide-presenting activity, major histocompatibility complex (MHC) class II antigens can activate different cellular functions in immune and nonimmune cells. However, this "nonclassical" role and its functional consequences are still substantially overlooked. In this review, we will focus on these alternative functional properties of MHC class II antigens, to reawaken attention to their present and foreseeable immunobiologic and pathogenetic implications. The main issues that will be addressed concern 1) the role of MHC class II molecules as basic components of exchangeable oligomeric protein complexes with intracellular signaling ability; 2) the nonclassical functions of MHC class II antigens in immune cells; 3) the pathogenetic role of MHC class II antigens in inflammatory/autoimmune and infectious disease; and 4) the functional role of MHC class II antigens in solid malignancies.

Pure subdural haematomas of arteriolar origin.

Fifteen consecutive cases of subdural haematomas (SDHs) of arteriolar origin operated on during the last twenty years in the Neurosurgical Clinic of the University of Genoa are reported. These SDHs are rare and form as a result of a rupture of a cortical arteriolar branch typically on the vicinity of the Sylvian fissure. They are always in a pure form and never associated with parenchymal lesions. Their aetiology is spontaneous, as in the 40% of our series, or more frequently related to minor traumas. These SDHs are often encountered in elderly patients generally presenting with severe clinical conditions (in the 60% of our patients GCS on admission was < 8). Prompt surgical treatment is required in all cases before further worsening of their neurological condition, even if CT scanning does not reveal parenchymal lesions. The mortality rate is over 50% and mainly relates to the pre-operative GC score. Clinical features, neuroradiological aspects and treatment are discussed and literature reviewed.

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.