On the gene expression landscape of cancer.

Kauffman picture of normal and tumor states as attractors in an abstract state space is used in order to interpret gene expression data for 15 cancer localizations obtained from The Cancer Genome Atlas. A principal component analysis of this data unveils the following qualitative aspects about tumors: 1) The state of a tissue in gene expression space can be described by a few variables. In particular, there is a single variable describing the progression from a normal tissue to a tumor. 2) Each cancer localization is characterized by a gene expression profile, in which genes have specific weights in the definition of the cancer state. There are no less than 2500 differentially-expressed genes, which lead to power-like tails in the expression distribution functions. 3) Tumors in different localizations share hundreds or even thousands of differentially expressed genes. There are 6 genes common to the 15 studied tumor localizations. 4) The tumor region is a kind of attractor. Tumors in advanced stages converge to this region independently of patient age or genetic characteristics. 5) There is a landscape of cancer in gene expression space with an approximate border separating normal tissues from tumors.

Estrategia didáctica para la habilidad toma de decisiones en la formación del especialista en Pediatría

Fundamento: la toma de decisiones como habilidad profesional en la formación del especialista en Pediatría es un aspecto que requiere atención desde el punto de vista didáctico. Objetivo presentar una estrategia didáctica para la toma de decisiones como habilidad profesional en la formación del especialista en Pediatría, así como un acercamiento a su implementación. Métodos se utilizaron métodos y técnicas de investigación cualitativa como la observación y el grupo de discusión mediante talleres para describir los resultados que se presentan en el artículo. Resultados se ofrecen acciones metodológicas llevadas a cabo mediante la ejecución de un taller de socialización, el registro de actividades prácticas con profesores/tutores y residentes en diferentes escenarios docente-asistenciales. Se muestran los resultados de la implementación de las acciones de la estrategia didáctica, así como las premisas y etapas que se determinaron durante su proceso de construcción. Se describen las principales regularidades. Conclusiones: la estrategia didáctica propuesta, y su carácter flexible, permiten su articulación durante los tres años de residencia de Pediatría, en beneficio de la toma de decisiones como habilidad profesional y asumiendo el principio de educación en el trabajo como la principal forma de enseñanza del especialista en formación.

Background: decision-making as a professional skill in the training of the Pediatrics specialist is an aspect that requires attention from the didactic point of view. Objective: to present a didactic strategy for decision making as a professional skill in the Pediatrics specialist training, as well as an approach to its implementation. Methods: Qualitative research methods and techniques such as observation and group discussion through workshops were used to describe the results presented in the article. Results: methodological actions carried out through the execution of a socialization workshop, the record of practical activities with teachers/tutors and residents in different teaching-assistance scenarios are offered. The results of the implementation of the actions of the didactic strategy are shown, as well as the premises and stages that were determined during its construction process. The main regularities are described. Conclusions: the proposed didactic strategy, and its flexible nature, allow its articulation during the three years of Pediatrics residency, to the benefit of decision-making as a professional skill and assuming the principle of education at work as the main way of teaching the pediatrician training specialist.

Murine Mammary Carcinoma Induces Chronic Systemic Inflammation and Immunosuppression in BALB/c Mice.

PURPOSE: The F3II cell line is a highly invasive variant of mammary carcinoma. Although it is frequently used as a model to evaluate the efficacy of immunotherapy, its impact on the immune system remains poorly understood. The main objectives of this study were to evaluate the effects of F3II tumors on the development of chronic inflammation and to characterize tumor-associated immunosuppression. METHODS: Following the experimental implantation of F3II tumors in BALB/c mice, alterations in the liver and spleen anatomy and the numbers of circulating leukocytes, myeloid-derived suppressor cells (MDSCs), and regulatory T cells were measured using hematological techniques, histopathological analysis, and flow cytometry. The capacity of the F3II tumor-bearing mice to reject MB16F10 allogeneic tumor transplantation was also evaluated. In addition, the restoration of immune parameters in tumor-bearing mice was evaluated after standard breast cancer chemotherapy and surgical tumor excision. RESULTS: F3II tumor implantation increased the levels of chronic inflammatory markers, such as the neutrophil-to-lymphocyte and platelet-to-lymphocyte ratios, and caused myeloid alterations, including extramedullary granulopoiesis and megakaryopoiesis, along with the recruitment of MDSCs to the spleen. Chemotherapy or surgical F3II tumor removal completely rescued the tumor-associated extramedullary granulopoiesis and megakaryopoiesis. Notably, the presence of F3II tumors reduced the capacity of BALB/c mice to reject MB16F10 allogeneic tumor transplantation. CONCLUSION: These results support the occurrence of F3II tumor-mediated immune cell dysfunction, which mimics the immune alterations characterized by chronic systemic inflammation and immunosuppression observed in breast cancer in clinical settings. Thus, the F3II tumor model is relevant for evaluating novel breast cancer immunotherapies and combinations in preclinical studies. This model could also be useful for identifying appropriate therapeutic targets and developing proof-of-concept experiments in the future.

Guía de Práctica Clínica de litiasis vesicular en niños y adolescentes / Clinical Practice Guidelines of Vesicular Lithiasis in Children and Adolescents

La litiasis vesicular en la infancia y adolescencia ha acusado un notable incremento en los últimos años. En países europeos, como Inglaterra, las colecistectomías se han triplicado desde 1997 y en el 2012 en el Hospital Infantil de Santiago de Cuba representó el 96,4 por ciento de todas las operaciones mayores electivas. En el IV Simposio Nacional de Cirugía Pediátrica (Varadero, Matanzas, 1- 3 de julio de 2019) fue presentada, discutida y aprobada esta "Guía de Práctica Clínica de litiasis vesicular en niños y adolescentes" y se recomendó, al concluir dicho evento, compartir dicha guía a través de su publicación, para que los servicios de cirugía pediátrica la empleen como referencia y la apliquen en las instituciones del sistema cubano de salud encargadas de la atención sanitaria de niños y adolescentes(AU)

Vesicular lithiasis in childhood and adolescence has had a marked increase in recent years. In European countries such as England, cholecystectomies have tripled since 1997 and in 2012 at the Children's Hospital in Santiago de Cuba accounted for 96.4 percent of all major elective operations. At the IV National Symposium on Pediatric Surgery (Varadero, Matanzas, July 1-3, 2019) this " Clinical Practice Guidelines of Vesicular Lithiasis in Children and Adolescents" was presented, discussed and approved, and it was recommended, at the conclusion of that event, to share this guidelines through its publication, for pediatric surgery services to use it as a reference and to be applied in the institutions of the Cuban health system which are responsible for the health care of children and adolescents(AU)

Concepciones sobre la formación del especialista en pediatría en Cuba: desafíos didácticos / Approaches about pediatric specialist training in Cuba: didactic challenges

RESUMEN La formación del pediatra cubano ha transitado por diferentes momentos a través de los años. El objetivo de este artículo es caracterizar la enseñanza de la pediatría cubana en las diferentes etapas: colonia, neocolonia y Revolución en el poder, en que la enseñanza pasó de un carácter biologicista y expositivo a vincular la teoría con la práctica. El programa de la especialidad de pediatría expresa el sistema de habilidades y conocimientos que debe desarrollar el educando en cada módulo, estancia o asignatura. Se aplican tres tipos de evaluación: evaluación en el curso de la residencia, por año, evaluación de fin de año y examen estatal. Los nuevos tiempos enfrentan desafíos que requieren de un pediatra integral con alto grado de formación, autonomía y buenas decisiones, lo que implica la intencionalidad didáctica en su orientación, desarrollo y evaluación.

ABSTRACT The training of the Cuban pediatrician has gone through different moments through the years. The objective of this article is to characterize the teaching of Cuban pediatrics in the different stages: colony, neo-colony and Revolution in power, in which the teaching went from a biologists and expository character to linking theory with practice. The pediatrics specialty program expresses the system of skills and knowledge that the student must develop in each module, stay or subject. Three types of assessment are applied: assessment in the course of residency, per year, end-of-year assessment, and state examination. New times face challenges that require a comprehensive pediatrician with a high degree of training, autonomy and good decisions, which require didactic intentionality in their orientation, development and assessment.

Coccidioidomycosis in Biopsies with Presumptive Diagnosis of Malignancy in Dogs: Report of Three Cases and Comparative Discussion of Published Reports.

Coccidioidomycosis is a respiratory fungal infection with occasional systemic dissemination. The disseminated coccidioidomycosis is considered a multifaceted disease. In medicine, disseminated coccidioidomycosis is included within a group of infectious diseases that have been referred as the great imitators. In many cases, malignancies are included in the presumptive diagnosis. In veterinary medicine, disseminated coccidioidomycosis is common in dogs. Nonetheless, despite of being a diagnostic dilemma, disseminated coccidioidomycosis is underestimated and frequently not included into differentials, even in endemic zones. Herein, we describe three cases of granulomatous inflammation caused by Coccidioides spp. which were masquerading malignancies in dogs (0.39 %). The presumptive diagnoses in these cases were osteosarcoma, lymphoma and neurofibroma, respectively. A PCR assay employing tissues in paraffin blocks resulted positive for C. posadasii in one of these cases. A comparative discussion on the ambiguous clinic-pathological presentation of disseminated coccidioidomycosis in dogs and humans is included.

High EGFR and low p-Akt expression is associated with better outcome after nimotuzumab-containing treatment in esophageal cancer patients: preliminary clinical result and testable hypothesis.

The epidermal growth factor receptor (EGFR) is widely overexpressed in esophageal squamous cell carcinoma (ESCC) and it results is associated with a poor prognosis. Identifying the subgroup of ESCC patients who are sensitive to EGFR-targeted therapy is a key point to facilitate its medical use.We retrospectively analyzed 32 ESCC patients treated with the combination of nimotuzumab (h-R3) and radiotherapy (RT) or chemoradiotherapy (CRT). Expression of EGFR and phosphorylated proteins associated with EGFR signaling pathway, i.e. p-Akt and p-Erk, were assessed with immunohistochemistry (IHC) for all patients. Correlations between these proteins' expression levels and overall survival (OS) were assessed.High expression of EGFR, p-Akt and p-Erk was detected in 53.1% (17/32), 54.8% (17/31) and 59.4% (19/32) of tumors respectively. No significant differences in OS were found between high EGFR, p-Akt and p-Erk expression groups and their respective counterparts. Of note, significantly better overall survival was observed in patients with coexistence of high EGFR expression and low p-Akt expression (p = 0.030).Our data allowed us to put forward a hypothesis that high EGFR and low p-Akt expression may predict a clinical benefit of EGFR antagonists such as nimotuzumab combined with RT or CRT. This can be discussed in the terms of oncogene addiction and synthetic lethality concepts. This hypothesis can be further tested in larger groups of patients.

Oncogenic Transformation Can Orchestrate Immune Evasion and Inflammation in Human Mesenchymal Stem Cells Independently of Extrinsic Immune-Selective Pressure.

Immune escape is a hallmark of cancer, but whether it relies upon extrinsic immune-selective pressure or is inherently orchestrated by oncogenic pathways is unresolved. To address this question, we took advantage of an in vitro model of sequentially transformed human mesenchymal stem cells (hMSC). Neoplastic transformation in this model increased the natural immune-evasive properties of hMSC, both by reducing their immunogenicity and by increasing their capacity to inhibit mitogen-driven T-cell proliferation. We also found that IFNγ signaling was globally affected in transformed hMSC. As a consequence, the natural inhibitory effect of hMSC on T-cell proliferation switched from an inducible mechanism depending on IFNγ signaling and mediated by indoleamine 2,3-dioxygenase to a constitutive mechanism that relied upon IL1ß involving both secreted and membrane-expressed molecules. After transformation, increased IL1ß expression both sustained the immunosuppressive properties of hMSC and increased their tumorigenicity. Thus, in this model system, IL1ß acted as intrinsic inflammatory mediator that exerted an autocrine influence on tumor growth by coordinately linking immune escape and tumorigenicity. Collectively, our findings show how oncogenes directly orchestrate inflammation and immune escape to drive the multistep process of cancer progression, independently of any need for immunoediting in the tumor microenvironment.

Predicting the right spacing between protein immobilization sites on self-assembled monolayers to optimize ligand binding.

Self-assembled monolayers designed to immobilize capture antibodies are usually prepared using a mixture of functional and inactive linkers. Here, using low molar ratios (1:1 to 1:100) of the two linkers resulted in loss of binding capability of the anti-EGFR (epidermal growth factor receptor) antibody nimotuzumab, as assessed by surface plasmon resonance imaging. We then developed a simple theoretical model to predict the optimal surface density of the functional linker, taking into account the antibody size and linker diameter. A high (1:1000) dilution of the functional linker yielded the best results. As an advantage, this approach does not require chemical modification of the protein.

Oncogenic transformation tunes the cross-talk between mesenchymal stem cells and T lymphocytes.

Stem cells from mesenchymal origin (MSC) exert a plethora of immunomodulatory effects. We created a neoplastic model based on in vitro step-wise transformation to assess whether oncogenic pathways have the capacity to mould the cross-talk of MSC and lymphocytes. Neoplastic MSC exhibit an increased inhibitory effect on T cell proliferation, either directly or mediated by myeloid derived suppressor cells. Additionally, transformation of MSC enhances T cell apoptosis without reducing either the percentage of CD25 expressing cells or the level of this protein expression. Malignant transformation drives MSC to lose dependency on nitric oxide for immunosuppression whilst increasing the constitutive production of PGE2. Our results indicate that oncogenesis tunes the interplay between MSC and immune cells, favoring cancer immune evasion.

A randomized, multicenter, placebo-controlled clinical trial of racotumomab-alum vaccine as switch maintenance therapy in advanced non-small cell lung cancer patients.

PURPOSE: Racotumomab-alum is an anti-idiotype vaccine targeting the NeuGcGM3 tumor-associated ganglioside. This clinical trial was conducted to provide a preliminary estimate of efficacy and safety of racotumomab as switch maintenance for patients with advanced non-small cell lung cancer (NSCLC). EXPERIMENTAL DESIGN: Patients with stage IIIb/IV NSCLC who have at least stable disease after first-line chemotherapy were randomized 1:1 to racotumomab-alum (5 immunizations every 2 weeks and re-immunizations every 4 weeks) or placebo. Treatment was administered beyond progressive disease, until severe performance status worsening or toxicity. At progression, only five patients per group received further anticancer therapy. The primary endpoint was overall survival (OS). RESULTS: One-hundred and seventy-six patients were randomized to racotumomab-alum (n = 87) and placebo (n = 89). Median OS was 8.23 and 6.80 months, respectively [HR, 0.63; 95% confidence interval (CI), 0.46-0.87; P = 0.004]. Median progression-free survival (PFS) in vaccinated patients was 5.33 versus 3.90 months for placebo (HR, 0.73; 95% CI 0.53-0.99; P = 0.039). The most common adverse events in the racotumomab-alum arm were burning and pain at the injection site, bone pain, and asthenia. A high antibody response of IgM and IgG isotype against the NeuGcGM3 ganglioside was obtained. Hyperimmune sera were able to specifically recognize and kill the NeuGcGM3-expressing L1210 cell line. Patients who developed anti-NeuGcGM3 antibodies capable to bind and kill ≥30% L1210 cells showed longer median survival times. CONCLUSIONS: Switch maintenance with racotumomab-alum is an effective and a well-tolerated treatment option for patients with advanced NSCLC.

Role of B-1 cells in the immune response against an antigen encapsulated into phosphatidylcholine-containing liposomes.

B-1 lymphocytes comprise a unique subset of B cells that differ phenotypically, ontogenetically and functionally from conventional B-2 cells. A frequent specificity of the antibody repertoire of peritoneal B-1 cells is phosphatidylcholine. Liposomes containing phosphatidylcholine have been studied as adjuvants and their interaction with dendritic cells and macrophages has been demonstrated. However, the role of B-1 cells in the adjuvanticity of liposomes composed of phosphatidylcholine has not been explored. In the present work, we studied the contribution of B-1 cells to the humoral response against ovalbumin (OVA) encapsulated into dipalmitoylphosphatidylcholine (DPPC) and cholesterol-containing liposomes. BALB/X-linked immunodeficient (xid) mice, which are deficient in B-1 cells, showed quantitative and qualitative differences in the anti-OVA antibody response compared with wild-type animals after immunization with these liposomes. The OVA-specific immune response was significantly increased in the BALB/xid mice when reconstituted with B-1 cells from naive BALB/c mice. Our results indicate the internalization of DPPC-containing liposomes by these cells and their migration from the peritoneal cavity to the spleen. Phosphatidylcholine significantly contributed to the immunogenicity of liposomes, as DPPC-containing liposomes more effectively stimulated the anti-OVA response compared with vesicles composed of dipalmitoylphosphatidylglycerol. In conclusion, we present evidence for a cognate interaction between B-1 cells and phosphatidylcholine liposomes, modulating the immune response to encapsulated antigens. This provides a novel targeting approach to assess the role of B-1 cells in humoral immunity.

Liposomes of phosphatidylcholine and cholesterol induce an M2-like macrophage phenotype reprogrammable to M1 pattern with the involvement of B-1 cells.

Macrophages respond to endogenous and non-self stimuli acquiring the M1 or M2 phenotypes, corresponding to classical or alternative activation, respectively. The role of B-1 cells in the regulation of macrophage polarization through the secretion of interleukin (IL)-10 has been demonstrated. However, the influence of B-1 cells on macrophage phenotype induction by an immunogen that suppress their ability to secrete IL-10 has not been explored. Here, we studied the peritoneal macrophage pattern induced by liposomes comprised of dipalmitoylphosphatidylcholine (DPPC) and cholesterol (Chol) carrying ovalbumin (OVA) (Lp DPPC/OVA), and the involvement of B-1 cells in macrophage polarization. Peritoneal cells from BALB/c, B-1 cells-deficient BALB/xid and C57BL/6 mice immunized with Lp DPPC/OVA and OVA in soluble form (PBS/OVA) were analyzed and stimulated or not in vitro with lipopolysaccharide (LPS). Peritoneal macrophages from BALB/c and C57BL/6 mice immunized with Lp DPPC/OVA showed an M2-like phenotype as evidenced by their high arginase activity without LPS stimulation. Upon stimulation, these macrophages were reprogrammable toward the M1 phenotype with the upregulation of nitric oxide (NO) and a decrease in IL-10 secretion. In addition, high IFN-γ levels were detected in the culture supernatant of peritoneal cells from BALB/c and C57BL/6 mice immunized with Lp DPPC/OVA. Nevertheless, still high levels of arginase activity and undetectable levels of IL-12 were found, indicating that the switch to a classical activation state was not complete. In the peritoneal cells from liposomes-immunized BALB/xid mice, levels of arginase activity, NO, and IL-6 were below those from wild type animals, but the last two products were restored upon adoptive transfer of B-1 cells, together with an increase in IFN-γ secretion. Summarizing, we have demonstrated that Lp DPPC/OVA induce an M2-like pattern in peritoneal macrophages reprogrammable to M1 phenotype after LPS stimulation, with the involvement of B-1 cells.

Effects of an epidermal growth factor receptor-based cancer vaccine on wound healing and inflammation processes in murine experimental models.

Anti-epidermal growth factor receptor (EGFR) therapies have been proven clinically effective for a variety of epithelial tumours. Vaccination of mice with the extracellular domain (ECD) of autologous EGFR overcomes the tolerance to self-EGFR and has antimetastatic effect on EGFR+ tumour. Because EGF/EGFR-signalling plays an important role in the inflammation stage of wound healing, the main objective of this study was to explore the possible role of murine (m) EGFR-ECD vaccine in the croton-oil-induced ear oedema and wound healing process in mice as autologous experimental models, mimicking the possible post-surgical wound complication in patients treated with human EGFR-ECD/VSSP vaccine. Mice were intramuscularly immunised four times; biweekly with the mEGFR-ECD/VSSP/Mont. Seven days later, an 8 mm diameter, full-thickness skin wound was created on the back of each animal. Immunisation induced a strong specific humoral response against the mEGFR-ECD protein and a DTH dose-response curve but interestingly, animals treated with mEGFR-ECD/VSSP/Mont had similar inflammatory and healing speed responses compared to control ones. These data suggest that application of mEGFR-ECD/VSSP vaccine as a therapeutic approach in cancer patients could not elicit a poor healing process after surgery.

EGFR-targeting therapy as an evolving concept: learning from nimotuzumab clinical development.

Epidermal growth factor receptor (EGFR)-targeted therapies have been extensively evaluated in the clinic for different tumor localizations and using different EGFR-targeting products, either registered or still in clinical development. Nonetheless, there still is a long way to go to optimize the clinical benefit from EGFR-targeted therapies. In this article we briefly discuss on current paradigms guiding the use of EGFR-targeting agents in the clinic, and on new emergent concepts. The discussion is largely based on experiences from the clinical development of the monoclonal antibody nimotuzumab, which has shown a quite particular clinical profile, characterized by a very low toxicity. In order to optimize the design of EGFR-targeting therapies, clinical researchers should take into account the interconnection between the EGFR pathway and other cellular pathways. Thus, clinical trials need to incorporate more translational research.

Análisis estadístico de indicadores de calidad del hospital Dr. Joaquín Castillo Duany / Statistics analysis of quality indicators of the hospital Dr. Joaquín Castillo Duany

La presente investigación se desarrolla en la sala de cuidados intensivos del hospital Dr. Joaquín Castillo Duany, de Santiago de Cuba, donde se aplica el análisis multivariado con el objetivo de determinar un modelo econométrico que permita estimar y evaluar los costos de calidad, contribuyendo significativamente a la obtención de la excelencia en los servicios de salud y al proceso de perfeccionamiento hospitalario. La investigación se sustenta en la aplicación de la correlación canónica como técnica multivariante muy potente y poco explotada, utilizando los principales pilares de la econometría como ciencia aplicada, donde se recopilan los indicadores de calidad y eficiencia con la finalidad de realizar un análisis multivariado, que ha permitido obtener un modelo econométrico para la estimación de los costos de calidad en el servicio seleccionado. El modelo aplicado, ha permitido cuantificar y evaluar el comportamiento de los costos de calidad, siendo de gran utilidad para generalizarlo a otros servicios en el sector de la salud. Constituye una herramienta de trabajo para la dirección de la entidad al permitir mejorar el proceso de toma de decisiones en relación con los costos de calidad y evaluar los niveles de eficiencia en los servicios de salud(AU)

The present investigation was done at the intensive care unit of the hospital Dr. Joaquín Castillo Duany in Santiago de Cuba. Multivariate analysis is applied in order to determine and apply a scientific econometric model that helps to estimate and evaluate quality costs, this model will contribute significantly on obtaining a better health service in the hospital. The investigation helps the general fundamental theory upon the quality cost and the application of the canonical correlation as a very potent and little exploited multivariate technique using the principal pillars of the econometrics as an applied science. The indicators of quality and efficiency with the final statistics has permitted us to obtain a mathematical model that permits the estimation of quality cost in the service selected. The above mentioned model application has permitted us to quantify and evaluate the conduct of the quality cost, making it a great utility to generalise to other entity services which constitutes a tool for improve decision making in relation with the cost of quality. It also benefits the evaluation of efficiency level in the health service(AU)

A view on EGFR-targeted therapies from the oncogene-addiction perspective.

Tumor cell growth and survival can often be impaired by inactivating a single oncogen- a phenomenon that has been called as "oncogene addiction." It is in such scenarios that molecular targeted therapies may succeed. among known oncogenes, the epidermal growth factor receptor (EGFR) has become the target of different cancer therapies. So far, however, the clinical benefit from EGFR-targeted therapies has been rather limited. a critical review of the large amount of clinical data obtained with anti-EGFR agents, carried out from the perspective of the oncogene addiction concept, may help to understand the causes of the unsatisfactory results. In this article we intend to do such an exercise taking as basis for the analysis a few case studies of anti-EGFR agents that are currently in the clinic. There, the "EGFR addiction" phenomenon becomes apparent in high-responder patients. We further discuss how the concept of oncogene addiction needs to be interpreted on the light of emerging experimental evidences and ideas; in particular, that EGFR addiction may reflect the interconnection of several cellular pathways. In this regard we set forth several hypotheses; namely, that requirement of higher glucose uptake by hypoxic tumor cells may reinforce EGFR addiction; and that chronic use of EGFR-targeted antibodies in EGFR-addicted tumors would induce stable disease by reversing the malignant phenotype of cancer stem cells and also by sustaining an anti-tumor T cell response. Finally, we discuss possible reasons for the failure of certain combinatorial therapies involving anti-EGFR agents, arguing that some of these agents might produce either a negative or a positive trans-modulation effect on other oncogenes. It becomes evident that we need operational definitions of EGFR addiction in order to determine which patient populations may benefit from treatment with anti-EGFR drugs, and to improve the design of these therapies.

P3 mAb: An Immunogenic Anti-NeuGcGM3 Antibody with Unusual Immunoregulatory Properties.

P3 is a murine IgM mAb that recognize N-glycosylated gangliosides, sulfatides, and antigens expressed in melanoma, breast, and lung human tumors. This antibody has the ability to trigger an IgG antibody response in the syngeneic BALB/c model, even when it is administered in the absence of adjuvant or carrier protein. The mechanism by which the P3 mAb, a self-immunoglobulin, induce this immune response in the absence of co-stimulatory or classical danger signals is still unknown. In the present paper we show that the high immunogenicity of P3 mAb depends not only on CD4 but also on CD8(+) T cells, since the depletion of CD8(+) or CD4(+) T cells led to the loss of P3 mAb immunogenicity in the syngeneic model. Furthermore, the immunization with P3 mAb enhanced the recovery of the CD8(+) T cell population in mice treated with an anti-CD8a antibody. Additionally, the immunization with P3 mAb restored the capacity of immunosuppressed mice to reject allogeneic tumors, a mechanism mediated by the action of CD8(+) T cells. Finally, in mice with cyclophosphamide induced lymphopenia, the administration of P3 mAb accelerated the recovery of both CD4(+) and CD8(+) T cells. These results show new possibilities for B and CD8(+) T cells interactions during the immune response elicited by a self-protein. Furthermore they point to P3 mAb as a potential interesting candidate for the treatment of immunosuppressed patients.

Induction of immunogenic apoptosis by blockade of epidermal growth factor receptor activation with a specific antibody.

Despite promising results in the use of anti-epidermal growth factor receptor (EGFR) Abs for cancer therapy, several issues remain to be addressed. An increasing emphasis is being placed on immune effector mechanisms. It has become clear for other Abs directed to tumor targets that their effects involve the adaptive immunity, mainly by the contribution of Fc region-mediated mechanisms. Given the relevance of EGFR signaling for tumor biology, we wonder whether the oncogene inhibition could contribute to Ab-induced vaccine effect. In a mouse model in which 7A7 (an anti-murine EGFR Ab) and AG1478 (an EGFR-tyrosine kinase inhibitor) displayed potent antimetastatic activities, depletion experiments revealed that only in the case of the Ab, the effect was dependent on CD4(+) and CD8(+) T cells. Correspondingly, 7A7 administration elicited a remarkable tumor-specific CTL response in hosts. Importantly, experiments using 7A7 F(ab')(2) suggested that in vivo Ab-mediated EGFR blockade may play an important role in the linkage with adaptive immunity. Addressing the possible mechanism involved in this effect, we found quantitative and qualitative differences between 7A7 and AG1478-induced apoptosis. EGFR blocking by 7A7 not only prompted a higher proapoptotic effect on tumor metastases compared with AG1478, but also was able to induce apoptosis with immunogenic potential in an Fc-independent manner. As expected, 7A7 but not AG1478 stimulated exposure of danger signals on tumor cells. Subcutaneous injection of 7A7-treated tumor cells induced an antitumor immune response. This is the first report, to our knowledge, of a tumor-specific CTL response generated by Ab-mediated EGFR inhibition, suggesting an important contribution of immunogenic apoptosis to this effect.