RESUMEN
Chronic immune thrombocytopenia (cITP) is often associated with an underlying predisposition towards autoimmunity, recognition of which is relevant to guide treatment. International recommendations on diagnostic steps and therapeutic measures of cITP in childhood exist. However, due to the low prevalence (1-2/100,000) and a variation of availability of immunological and hematological tests and treatments across pediatric units, we postulated that these guidelines are not uniformly adhered to and that immune dysregulation syndromes remained undiscovered. To delineate the current management of children and adolescents with cITP in Austria, we performed a nationwide cross-sectional study. Between 2011 and 2014, 81 children with cITP were seen at seven centers (median age 8.75 years; range 1-17; female:male ratio 47:34) at 641 visits during 180 patient years after diagnosis of cITP (>12 months ITP duration). Additional diagnoses were noted, most frequently immune or autoimmune disorders, hematologic diseases, or infections (in 37.3%, including Evans syndrome, autoimmune lymphoproliferative syndrome, systemic lupus erythematosus, and Fanconi anemia), or other symptoms like bi- or pancytopenia (n=9), lymphoproliferation or granulomatous inflammation (n = 3). Both decision to treat as well as choice of treatment varied: smaller centers tended to observe more frequently, larger centers applied a pattern of treatment modalities that appeared to depend less on bleeding tendency than on center policy. More than 50% of therapeutic interventions occurred in bleedings scores ≤2 (of 5), suggesting a strong psychosocial intention to treat. Platelet increment upon 479 therapeutic interventions of eight types was evaluated, with multiple treatment approaches being pursued sequentially in refractory patients. These data confirm the hypothesis of heterogeneous diagnostic and therapeutic management of cITP in Austrian children and corroborate the need for (1) a precise panel of parameters to exclude underlying disorders and (2) for biomarkers to predict treatment response.
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Púrpura Trombocitopénica Idiopática/tratamiento farmacológico , Adolescente , Austria , Niño , Preescolar , Enfermedad Crónica , Estudios Transversales , Femenino , Humanos , Lactante , MasculinoAsunto(s)
Enfermedad Injerto contra Huésped , Trasplante de Células Madre Hematopoyéticas , Lectina de Unión a Manosa/deficiencia , Polimorfismo de Nucleótido Simple , Enfermedad Aguda , Adolescente , Aloinjertos , Niño , Preescolar , Supervivencia sin Enfermedad , Femenino , Enfermedad Injerto contra Huésped/sangre , Enfermedad Injerto contra Huésped/genética , Enfermedad Injerto contra Huésped/mortalidad , Humanos , Masculino , Tasa de SupervivenciaRESUMEN
INTRODUCTION: Complement immunodeficiencies (excluding hereditary angioedema and mannose binding lectin deficiency) are rare. Published literature consists largely of case reports and small series. We collated data from 18 cities across Europe to provide an overview of primarily homozygous, rather than partial genotypes and their impact and management. METHODS: Patients were recruited through the ESID registry. Clinical and laboratory information was collected onto standardized forms and analyzed using SPSS software. RESULTS: Seventy-seven patients aged 1 to 68 years were identified. 44 % presented in their first decade of life. 29 % had C2 deficiency, defects in 11 other complement factors were found. 50 (65 %) had serious invasive infections. 61 % of Neisseria meningitidis infections occurred in patients with terminal pathway defects, while 74 % of Streptococcus pneumoniae infections occurred in patients with classical pathway defects (p < 0.001). Physicians in the UK were more likely to prescribe antibiotic prophylaxis than colleagues on the Continent for patients with classical pathway defects. After diagnosis, 16 % of patients suffered serious bacterial infections. Age of the patient and use of prophylactic antibiotics were not associated with subsequent infection risk. Inflammatory/autoimmune diseases were not seen in patients with terminal pathway, but in one third of patients classical and alternative pathway defects. CONCLUSION: The clinical phenotypes of specific complement immunodeficiencies vary considerably both in terms of the predominant bacterial pathogen, and the risk and type of auto-inflammatory disease. Appreciation of these phenotypic differences should help both immunologists and other specialists in their diagnosis and management of these rare and complex patients.
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Proteínas del Sistema Complemento/deficiencia , Proteínas del Sistema Complemento/genética , Síndromes de Inmunodeficiencia/epidemiología , Síndromes de Inmunodeficiencia/genética , Adolescente , Adulto , Anciano , Niño , Preescolar , Activación de Complemento/genética , Activación de Complemento/inmunología , Proteínas del Sistema Complemento/inmunología , Consanguinidad , Bases de Datos Factuales , Manejo de la Enfermedad , Europa (Continente)/epidemiología , Femenino , Genotipo , Humanos , Síndromes de Inmunodeficiencia/diagnóstico , Síndromes de Inmunodeficiencia/terapia , Lactante , Masculino , Persona de Mediana Edad , Adulto JovenRESUMEN
PURPOSE: Intensification of antileukemic treatment and progress in supportive management have improved the survival rates of children with acute myeloid leukemia (AML). However, morbidity and early mortality in these patients are still very high, especially in children with acute monoblastic leukemia (AML FAB M5). Inflammatory syndromes complicating the management of these children after application of cytosine arabinoside and due to hyperleukocytosis at initial presentation have been reported. Hemophagocytic lymphohistiocytosis (HLH) has been described as a serious and life-threatening acute complication during treatment of different oncologic entities; however, data on HLH in children with AML FAB M5 are extremely rare. METHODS: A retrospective study of all children with AML FAB M5 treated at our institution between 1993 and 2013 was performed to describe the clinical characteristics of patients who developed an inflammatory syndrome with HLH during oncologic treatment. RESULTS: Three of 10 children developed an inflammatory syndrome with fever, elevation of C-reactive protein, hyperferritinemia, elevation of soluble interleukin-2, and hemophagocytosis during prolonged aplasia following the first cycle of chemotherapy not responding to broad-spectrum antibiotics. No infectious agents could be identified; the initial symptoms occurred 17, 18, and 28 days after diagnosis of AML, respectively. The children immediately responded to dexamethasone; however, the same syndrome was observed again after the second cycle of chemotherapy and, in one patient, also after the third cycle. CONCLUSIONS: Treating physicians should be aware of an inflammatory syndrome resembling HLH in children with monoblastic leukemia since this problem might extremely complicate management and supportive care of these children. The co-incidence of monoblastic leukemia with HLH might be explained by cytokines released from the monoblastic leukemic cells themselves.
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Fiebre de Origen Desconocido/patología , Leucemia Monocítica Aguda/patología , Linfohistiocitosis Hemofagocítica/patología , Adolescente , Adulto , Proteína C-Reactiva/metabolismo , Niño , Preescolar , Femenino , Fiebre de Origen Desconocido/diagnóstico , Fiebre de Origen Desconocido/metabolismo , Humanos , Interleucina-2/metabolismo , Leucemia Monocítica Aguda/metabolismo , Linfohistiocitosis Hemofagocítica/diagnóstico , Linfohistiocitosis Hemofagocítica/metabolismo , Masculino , Estudios Retrospectivos , Tasa de Supervivencia , Adulto JovenRESUMEN
Clinical presentation and laboratory data are often too unspecific to distinguish the onset or activity of graft-versus-host disease (GvHD) from infections or toxicity. Antigen-presenting cells such as monocytes/macrophages and dendritic cells are involved in GvHD pathogenesis after allogeneic hematopoietic stem cell transplantation (HSCT). To test whether ferritin, an iron storage marker and macrophage activation-linked acute-phase protein, represents a candidate biomarker for acute or chronic GvHD in pediatric HSCT, we retrospectively evaluated a 2-year follow-up data from 131 eligible consecutive patients with different malignant and nonmalignant diseases who underwent allogeneic HSCT. Thirteen patients (10 %) suffered from acute GvHD II-IV°, 18 (14 %) had limited, and 14 (11 %) had extensive chronic GvHD. In extension of previous studies in adults investigating pre-transplant ferritin, our data show that post-HSCT hyperferritinemia (analyzed on days 0, +30, +60, +100, +180, +360, and +720) was significantly associated with decreased long-term survival (p < 0.001-0.03) in children and adolescents. Increased ferritin concentrations were associated with number and timing of red blood cell transfusions and toxic or infectious multi-organ failure but did not show significant differences between patients without GvHD and with acute grades II-IV, limited, or extensive chronic GvHD. Thus, our data do not identify ferritin as specifically GvHD-linked biomarker; however, they support the prognostic value of ferritin levels for outcome after HSCT in children.
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Ferritinas/sangre , Enfermedad Injerto contra Huésped/sangre , Trasplante de Células Madre Hematopoyéticas/efectos adversos , Adolescente , Adulto , Biomarcadores , Niño , Preescolar , Transfusión de Eritrocitos/estadística & datos numéricos , Femenino , Ferritinas/análisis , Estudios de Seguimiento , Enfermedad Injerto contra Huésped/diagnóstico , Enfermedad Injerto contra Huésped/etiología , Enfermedad Injerto contra Huésped/prevención & control , Enfermedades Hematológicas/cirugía , Neoplasias Hematológicas/cirugía , Humanos , Terapia de Inmunosupresión , Lactante , Recién Nacido , Linfohistiocitosis Hemofagocítica/epidemiología , Linfohistiocitosis Hemofagocítica/etiología , Masculino , Insuficiencia Multiorgánica/epidemiología , Complicaciones Posoperatorias/epidemiología , Valor Predictivo de las Pruebas , Estudios Retrospectivos , Acondicionamiento Pretrasplante , Trasplante Homólogo , Resultado del Tratamiento , Adulto JovenAsunto(s)
Antineoplásicos/uso terapéutico , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Arsenicales/uso terapéutico , Hemorragia Cerebral/inducido químicamente , Sustitución de Medicamentos , Leucemia Promielocítica Aguda/tratamiento farmacológico , Óxidos/uso terapéutico , Adolescente , Antineoplásicos/efectos adversos , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Trióxido de Arsénico , Arsenicales/efectos adversos , Hemorragia Cerebral/diagnóstico , Esquema de Medicación , Femenino , Estudios de Seguimiento , Humanos , Cuidados a Largo Plazo , Óxidos/efectos adversos , Inducción de Remisión , Tomografía Computarizada por Rayos XRESUMEN
Two related boys who died from fulminant infectious mononucleosis were diagnosed with X-linked lymphoproliferative disease type 1 (XLP-1). Family screening (n=17) identified 6 female mutation carriers and 2 more XLP-1 patients in whom, despite recurrent infections, agammaglobulinemia, and Hodgkin's Disease, the genetic basis had been unknown; demonstrating that awareness and early genetic testing are crucial to reveal underlying primary immunodeficiencies and improve outcome. Furthermore, XLP should be included routinely in the differential diagnosis of severe hypogammaglobulinemia and/or lymphoma in males.
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Mononucleosis Infecciosa/genética , Péptidos y Proteínas de Señalización Intracelular/genética , Linfohistiocitosis Hemofagocítica/genética , Trastornos Linfoproliferativos/genética , Adolescente , Agammaglobulinemia/diagnóstico , Agammaglobulinemia/genética , Preescolar , Análisis Mutacional de ADN , Infecciones por Virus de Epstein-Barr/diagnóstico , Infecciones por Virus de Epstein-Barr/genética , Exones/genética , Resultado Fatal , Tamización de Portadores Genéticos , Enfermedades Genéticas Ligadas al Cromosoma X/diagnóstico , Enfermedades Genéticas Ligadas al Cromosoma X/genética , Pruebas Genéticas , Enfermedad de Hodgkin/diagnóstico , Enfermedad de Hodgkin/genética , Humanos , Lactante , Mononucleosis Infecciosa/diagnóstico , Discapacidad Intelectual/diagnóstico , Discapacidad Intelectual/genética , Linfohistiocitosis Hemofagocítica/diagnóstico , Linfohistiocitosis Hemofagocítica/mortalidad , Trastornos Linfoproliferativos/diagnóstico , Trastornos Linfoproliferativos/mortalidad , Masculino , Meningoencefalitis/complicaciones , Meningoencefalitis/diagnóstico , Meningoencefalitis/genética , Mutación Missense , Linaje , Proteína Asociada a la Molécula de Señalización de la Activación Linfocitaria , Adulto JovenRESUMEN
CLTA4 is relevant for FOXP3(+)Treg cells, and the link between skewed X chromosome inactivation (XCI) and autoimmunity is recognized. The observation of immune dysregulation polyendocrinopathy enteropathy X-linked syndrome and multiorgan endocrine autoimmune phenomena in various members of one family, associated with a CTLA4 polymorphism and skewed XCI, provides an in vivo model of how mechanisms of immune dysregulation may cooperate.
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Enfermedades Autoinmunes/genética , Antígeno CTLA-4/genética , Factores de Transcripción Forkhead/genética , Predisposición Genética a la Enfermedad , Inactivación del Cromosoma X/genética , Adulto , Enfermedades Genéticas Ligadas al Cromosoma X/genética , Humanos , Masculino , Mutación , LinajeRESUMEN
Allogeneic hematopoietic stem cell transplantation (HSCT) in childhood is associated with severe pulmonary complications, but the pathophysiologic mechanisms remain unclear. Our aim was to evaluate the association of total and specific IgE, eosinophil cationic protein (ECP) and eosinophilia in HSCT recipients with pulmonary complications. We prospectively measured total and specific serum IgE, eosinophils, and ECP before and 28, 100, and 180 days after HSCT. We included 30 children (age 2-17 years) undergoing HSCT. Nine patients had a history of previous atopy without being associated with pulmonary complications after HSCT until day +360. Specific IgE levels showed a decline after HSCT, associated with the absence of allergy symptoms, suggesting a reduction of atopy. Elevated total serum IgE levels occurred in seven patients on day +28 after HSCT. This elevation did not coincide with allergy symptoms. ECP showed no correlation with total allergy symptoms, eosinophilia, IgE levels, or pulmonary complications. There was a significant correlation (p = 0.0367) between ECP levels on day +28 and concurrent acute graft-versus-host disease (GvHD). Non-atopic serum ECP and IgE levels are elevated on day +28 after HSCT in children, with ECP showing a potential relation to acute GvHD.
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Proteína Catiónica del Eosinófilo/sangre , Enfermedad Injerto contra Huésped/diagnóstico , Trasplante de Células Madre Hematopoyéticas/efectos adversos , Inmunoglobulina E/sangre , Adolescente , Niño , Preescolar , Neumonía en Organización Criptogénica/sangre , Neumonía en Organización Criptogénica/diagnóstico , Neumonía en Organización Criptogénica/epidemiología , Neumonía en Organización Criptogénica/etiología , Femenino , Enfermedad Injerto contra Huésped/sangre , Enfermedad Injerto contra Huésped/epidemiología , Enfermedad Injerto contra Huésped/inmunología , Trasplante de Células Madre Hematopoyéticas/estadística & datos numéricos , Humanos , Hipersensibilidad Inmediata/sangre , Hipersensibilidad Inmediata/epidemiología , Hipersensibilidad Inmediata/inmunología , Leucemia Mieloide Aguda/sangre , Leucemia Mieloide Aguda/diagnóstico , Leucemia Mieloide Aguda/epidemiología , Leucemia Mieloide Aguda/terapia , Enfermedades Pulmonares/sangre , Enfermedades Pulmonares/diagnóstico , Enfermedades Pulmonares/epidemiología , Enfermedades Pulmonares/etiología , Masculino , Leucemia-Linfoma Linfoblástico de Células Precursoras/sangre , Leucemia-Linfoma Linfoblástico de Células Precursoras/diagnóstico , Leucemia-Linfoma Linfoblástico de Células Precursoras/inmunología , Leucemia-Linfoma Linfoblástico de Células Precursoras/terapia , Prevalencia , Trasplante HomólogoRESUMEN
Autoimmune lymphoproliferative syndrome (ALPS) is mainly caused by defects in the CD95 pathway. Raised CD3+TCRαß+CD4-CD8- double negative T cells and impaired T cell apoptosis are hallmarks of the disease. In contrast, the B cell compartment has been less well studied. We found an altered distribution of B cell subsets with raised transitional B cells and reduced marginal zone B cells, switched memory B cells and plasma blasts in most of 22 analyzed ALPS patients. Moreover, 5 out of 66 ALPS patients presented with low IgG and susceptibility to infection revealing a significant overlap between ALPS and common variable immunodeficiency (CVID). In patients presenting with lymphoproliferation, cytopenia, hypogammaglobulinemia and impaired B cell differentiation, serum biomarkers were helpful in addition to apoptosis tests for the identification of ALPS patients. Our observations may indicate a role for apoptosis defects in some diseases currently classified as CVID.
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Síndrome Linfoproliferativo Autoinmune/diagnóstico , Síndrome Linfoproliferativo Autoinmune/inmunología , Linfocitos B/inmunología , Inmunodeficiencia Variable Común/diagnóstico , Inmunodeficiencia Variable Común/inmunología , Proteína Ligando Fas/sangre , Interleucina-10/sangre , Vitamina B 12/sangre , Adolescente , Adulto , Agammaglobulinemia/inmunología , Apoptosis , Biomarcadores/sangre , Niño , Preescolar , Diagnóstico Diferencial , Proteína Ligando Fas/inmunología , Citometría de Flujo , Humanos , Inmunoglobulina G/sangre , Interleucina-10/inmunología , Persona de Mediana Edad , Monocitos/inmunología , Fenotipo , Linfocitos T/inmunología , Vitamina B 12/inmunología , Receptor fas/sangre , Receptor fas/inmunologíaRESUMEN
Despite antibiotics, antifungals and haematopoietic growth factors, infections remain a major threat to neutropenic patients. To determine the role of granulocyte transfusions (GTs) in anti-infective therapy during neutropenia, GT administration was randomized in 74 adults with haematological or malignant diseases, febrile neutropenia and pulmonary or soft-tissue infiltrates after conventional or high-dose chemotherapy, a majority of them after allo-SCT (n=39). Neutrophil reconstitution was equal in the treatment and control arm. GT toxicity was minimal. The probability of 28-day survival after randomization was >80% in both groups, and no effect of GT on survival until day 100 could be detected in patients with fungal (n=55), bacterial or unknown infection (n=17) and various levels of neutropenia (ANC <500 vs >500 x 10(6)/l). These findings can be attributed primarily to procedural obstacles, such as long delay from randomization to first GT, low cell content and slow sequence of GT, difficulties in randomizing a safe and potentially life-saving treatment in severely endangered individuals, and a large proportion of rapidly recovering patients in both arms. The requirement of another trial in a more specific patient population with daily transfusions of sufficient numbers of granulocytes to support or refute the empirically acknowledged benefits of GT is discussed.
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Granulocitos/trasplante , Transfusión de Leucocitos , Neutropenia/terapia , Adolescente , Adulto , Anciano , Femenino , Enfermedades Hematológicas/complicaciones , Enfermedades Hematológicas/terapia , Humanos , Infecciones/mortalidad , Infecciones/terapia , Masculino , Persona de Mediana Edad , Neoplasias/complicaciones , Neoplasias/terapia , Neutropenia/mortalidad , Tasa de Supervivencia , Resultado del Tratamiento , Adulto JovenRESUMEN
Hematopoietic stem cell transplantation (HSCT) is complicated by unwelcome side-effects that arise on the basis of an altered immune system. Infectious complications and alloreactive T-cell responses trigger a process of ongoing immune activation and inflammation. Negative-feedback mechanisms to counteract inflammation involve the induction of the immunoregulatory enzyme indoleamine 2,3-dioxygenase (IDO), which mediates anti-inflammatory activities and T-cell inhibition via tryptophan catabolism. However, persistent immune activation and generalized release of pro-inflammatory cytokines deviate immune regulation towards chronic suppression incapable to abrogate the inflammatory response. This review focuses on the unique role of tryptophan catabolism in modulating inflammatory processes and T-cell responses after HSCT.
Asunto(s)
Trasplante de Células Madre Hematopoyéticas , Indolamina-Pirrol 2,3,-Dioxigenasa/inmunología , Animales , Humanos , Linfocitos T/inmunologíaRESUMEN
E2A-HLF, the chimeric fusion protein resulting from the leukemogenic translocation t(17;19), appears to employ evolutionarily conserved signaling cascades for its transforming and antiapoptotic functions. These arise from both impairment of normal E2A function and activation of a survival pathway triggered through the HLF bZip DNA binding and dimerization domain. Recent reports identify wild-type E2A as a tumor suppressor in T lymphocytes. Moreover, E2A-HLF has been shown to activate SLUG, a mammalian homologue of the cell death specification protein CES-1 in Caenorhabditis elegans, which appears to regulate an evolutionarily conserved cell survival program. Recently, several key mouse models have been generated, enabling further elucidation of these pathways on a molecular genetic level in vivo. In this review, we discuss the characteristics of both components of the fusion protein with regard to their contribution to the regulation of cell fate and the oncogenic potential of E2A-HLF.
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Proteínas de Unión al ADN/metabolismo , Proteínas de Unión al ADN/fisiología , Proteínas de Fusión Oncogénica/metabolismo , Proteínas de Fusión Oncogénica/fisiología , Translocación Genética , Animales , Apoptosis , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico , Caenorhabditis elegans , Linaje de la Célula , Supervivencia Celular , Proteínas de Unión al ADN/química , Evolución Molecular , Humanos , Leucemia/etiología , Leucemia/genética , Ratones , Modelos Biológicos , Proteínas de Fusión Oncogénica/química , Estructura Terciaria de Proteína , Transducción de Señal , Factores de TranscripciónRESUMEN
The A(2A)-adenosine receptor, a prototypical G(s)-coupled receptor, activates mitogen-activated protein (MAP) kinase in a manner independent of cAMP in primary human endothelial cells. In order to delineate signaling pathways that link the receptor to the regulation of MAP kinase, the human A(2A) receptor was heterologously expressed in Chinese hamster ovary (CHO) and HEK293 cells. In both cell lines, A(2A) agonist-mediated cAMP accumulation was accompanied by activation of the small G protein rap1. However, rap1 mediates A(2A) receptor-dependent activation of MAP kinase only in CHO cells, the signaling cascade being composed of G(s), adenylyl cyclase, rap1, and the p68 isoform of B-raf. This isoform was absent in HEK293 cells. Contrary to CHO cells, in HEK293 cells activation of MAP kinase by A(2A) agonists was not mimicked by 8-bromo-cAMP, was independent of Galpha(s), and was associated with activation of p21(ras). Accordingly, overexpression of the inactive S17N mutant of p21(ras) and of a dominant negative version of mSos (the exchange factor of p21(ras)) blocked MAP kinase stimulation by the A(2A) receptor in HEK 293 but not in CHO cells. In spite of the close homology between p21(ras) and rap1, the S17N mutant of rap1 was not dominant negative because (i) overexpression of rap1(S17N) failed to inhibit A(2A) receptor-dependent MAP kinase activation, (ii) rap1(S17N) was recovered in the active form with a GST fusion protein comprising the rap1-binding domain of ralGDS after A(2A) receptor activation, and (iii) A(2A) agonists promoted the association of rap1(S17N) with the 68-kDa isoform of B-raf in CHO cells. We conclude that the A(2A) receptor has the capacity two activate MAP kinase via at least two signaling pathways, which depend on two distinct small G proteins, namely p21(ras) and rap1. Our observations also show that the S17N version of rap1 cannot be assumed a priori to act as a dominant negative interfering mutant.
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Proteínas Quinasas Dependientes de Calcio-Calmodulina/metabolismo , Proteínas de Unión al GTP/metabolismo , Proteína Oncogénica p21(ras)/metabolismo , Receptores Purinérgicos P1/metabolismo , Transducción de Señal , Animales , Células CHO , Cricetinae , Activación Enzimática , Humanos , Factores de Transcripción/metabolismo , Factor de Intercambio de Guanina Nucleótido ral , Proteínas de Unión al GTP rapRESUMEN
Interleukin-2 (IL-2) and IL-12 modify the functional status of T- and natural killer (NK) cells by regulating proliferation, cytolytic activity, cytokine induction, and T-cell subset differentiation. These effects are exploited in immunotherapy of cancer patients with IL-2 or IL-12, which, however, is limited by potentially life-threatening side effects. IL-15 shares many of the biological activities of IL-2 and may therefore represent a therapeutic alternative. Here we have compared the ability of these interleukins to stimulate NK activity in peripheral blood lymphocytes (PBLs) isolated from healthy donors (n = 12) as well as from patients (n = 12) suffering from metastatic disease (melanoma). Target (K562) cell lysis was assessed by determining the release of 51Cr and lactate dehydrogenase (LDH) which gave equivalent results. The NK-resistant DAUDI cell line served as control target. Unstimulated NK activity was significantly lower in PBLs purified from melanoma patients. However, cytolytic activity was readily stimulated by preincubation of PBLs (18 h) with cytokines such that the maximum target cell lysis was comparable to that seen in PBL of healthy donors. Similarly, the potency of IL-2 (EC50 = 20.2+/-1.3 and 22.0+/-1.3 u/ml in healthy donors and patients, respectively), IL-12 (EC50 = 11.0+/-1.1 and 4.3+/-1.6 u/ml) and IL-15 (EC50 = 0.3+/-0.1 and 0.2+/-0.1 u/ml) was comparable. Importantly, if the preincubation was carried out with cytokine concentrations in the EC50 range, the effects of two cytokines (tested in all combinations) were additive. A synergism was evident in PBLs obtained both from healthy donors and melanoma patients if concentration-response curves for IL-12 were determined in the presence of increasing concentrations of IL-2 (enhanced efficacy) or IL-15 (enhanced efficacy and potency). Our observations suggest possible alternatives to the monotherapy with IL-2 (or IL-12) in cancer treatment. Provided that the present findings can be extrapolated to the situation in vivo, the combined administration of IL-12 and IL-15 may be as efficacious as the immunotherapy with IL-2; this approach ought to allow for a marked reduction in cytokine dose and thereby improve the therapeutic index.