Aspectos técnicos y clínicos de la prueba cruzada de histocompatibilidad en el trasplante de órganos solidos / Technical and clinical aspects of the histocompatibility crossmatch assay in solid organ transplantation

La presencia de anticuerpos dirigidos contra los antígenos leucocitarios humanos (Human Leukocyte Antigens, HLA) que se expresan en las células del donante, es uno de los factores de riesgo más importantes asociados con las complicaciones clínicas después del trasplante. La prueba cruzada es una de las pruebas de histocompatibilidad más eficaces para la detección de anticuerpos específicos contra el donante en los receptores de injertos. En los primeros métodos de la prueba cruzada, se utilizaba la citotoxicidad dependiente del complemento, que es útil para detectar dichos anticuerpos responsables del rechazo hiperagudo del injerto, pero carece de la sensibilidad adecuada. Por ello, se desarrollaron métodos de pruebas cruzadas más sensibles, entre ellas, la prueba cruzada por citometría de flujo que hoy se considera el método preferido. En este artículo se revisa la evolución de la prueba cruzada y los factores más importantes que deben tenerse en cuenta al realizarla y al interpretar los resultados de esta prueba fundamental para la supervivencia a largo plazo del injerto.

The presence of antibodies directed against human leukocyte antigens (HLA) expressed on donor cells is a significant risk factor for serious clinical complications after transplantation. The crossmatch assay is one of the most important tests available for the detection of donor-specific antibodies in potential allograft recipients. Early crossmatch methods utilized complement-dependent cytotoxicity, which is useful for detecting the donor-specific anti- HLA antibodies responsible for hyperacute allograft rejection but lacks adequate sensitivity. Consequently, more sensitive crossmatch methods have been developed, ultimately leading to the flow cytometry crossmatch as the currently preferred methodology. Herein, we review the evolution of the crossmatch assay and the most important factors to consider when performing and interpreting the results of this fundamental assay for ensuring the long-term survival of the transplanted organ.

Phasing out the pre-transplant cytotoxicity crossmatch: Are we missing something? / Exclusão da prova cruzada por citotoxicidade pré-transplante: estamos perdendo algo

Abstract Introduction: The anti-human globulin-enhanced complement-dependent cytotoxicity crossmatch (AHG-CDCXM) assay has been used to assess the presence of donor-specific antibodies (DSA) in recipient's serum before kidney transplantation. The flow cytometric crossmatch (FCXM) assay was first introduced as an additional test. The aim of this study was to clinically validate the single use of the FCXM assay. Methods: This study compared the outcomes of a cohort of kidney transplant patients that underwent FCXM only (FCXM group) versus a cohort of kidney transplant patients that underwent AHG-CDCXM (control group). Results: Ninety-seven patients in the FCXM group and 98 controls were included. All crossmatches in the control group were negative. One patient in the FCXM group had a positive B cell crossmatch. One year after transplantation, there were no significant differences in patient survival (p = 0.591) and graft survival (p = 0.692) between the groups. Also, no significant difference was found in the incidence of Banff ≥ 1A acute cellular rejection episodes (p = 0.289). However, acute antibody-mediated rejections occurred in 3 controls (p = 0.028). Conclusion: The results showed that discontinuing the AHG-CDCXM assay does not modify the clinical outcomes in a 1-year follow-up.

Resumo Introdução: O ensaio de prova cruzada por citotoxicidade dependente do complemento antiglobulina humana (AHG-CDCXM - do inglês anti-human globulin-enhanced complement-dependent cytotoxicity crossmatch) tem sido usado para avaliar a presença de anticorpos específicos contra o doador (DSA - do inglês donor-specific antibodies) no soro do receptor antes do transplante renal. O ensaio de prova cruzada por citometria de fluxo (CFXM) foi introduzido pela primeira vez como um teste adicional. O objetivo deste estudo foi validar clinicamente o uso único do ensaio CFXM. Métodos: Este estudo comparou os resultados de uma coorte de pacientes de transplante renal que foram submetidos apenas ao CFXM (grupo CFXM) contra uma coorte de pacientes de transplante renal submetidos ao AHG-CDCXM (grupo controle). Resultados: Foram incluídos noventa e sete pacientes no grupo CFXM e 98 controles. Todas as provas cruzadas no grupo controle foram negativas. Um paciente no grupo CFXM teve uma prova cruzada positiva para células B. Um ano após o transplante, não houve diferenças significativas na sobrevida do paciente (p = 0,591) e na sobrevida do enxerto (p = 0,692) entre os grupos. Também não foi encontrada diferença significativa na incidência de episódios de rejeição aguda celular (p = 0,289) segundo critério de Banff ≥ 1A. No entanto, rejeições agudas mediadas por anticorpos ocorreram em 3 controles (p = 0,028). Conclusão: Os resultados mostraram que a interrupção do ensaio AHG-CDCXM não modifica os desfechos clínicos em um acompanhamento de 1 ano.

Variaciones en el número y función de los linfocitos asesinos naturales durante infecciones recurrentes o graves / Variation in NK cell number and function in individuals with recurrent or severe infections

Introducción. Existen pocos datos sobre los defectos que afectan el desarrollo y función de los linfocitos asesinos naturales ( natural killers, NK) en pacientes con un incremento anormal en la recurrencia de infecciones. Objetivo. Realizar una evaluación sistemática de las diferentes subpoblaciones y la función de estas células en pacientes con infecciones recurrentes. Materiales y métodos. Se incluyeron 20 pacientes con infecciones graves o recurrentes y se analizaron las subpoblaciones y la respuesta citotóxica de los linfocitos NK en sangre periférica. Los resultados de los pacientes se compararon con controles sanos pareados por edad y sexo. Resultados. Los pacientes con episodios infecciosos activos presentaron anormalidades transitorias en el porcentaje o el número absoluto de linfocitos NK. Se caracterizaron, además, cinco pacientes con alteraciones persistentes en la distribución de las subpoblaciones de linfocitos NK. Estas alteraciones se debieron principalmente a la disminución de células CD56 dim CD16 bright . Se evidenciaron, también, defectos en la función de los linfocitos NK en algunos de nuestros pacientes; sin embargo, estas alteraciones fueron transitorias y se asociaron principalmente a la fase activa de la enfermedad. Conclusiones. Nuestros resultados evidencian defectos transitorios en el número y función de los linfocitos NK en pacientes con infecciones recurrentes o graves, además de alteraciones persistentes en los LNK CD56 dim CD16 bright en algunos individuos. Es necesario profundizar en los mecanismos que conllevan al desarrollo de estos defectos inmunes y estudiar cómo estas alteraciones influyen en la respuesta inmune.

Introduction: The information about defects affecting natural killer cell (NK) development and activity in patients with an abnormal increase of recurrent infections is scarce. Objective: To perform a systematic analysis of NK abnormalities in patients with recurrent infections. Materials and methods: Our study enrolled twenty patients with severe or recurrent viral infections. Natural killer cell subsets, surface receptors expression and cytotoxicity were analyzed. Results were compared with those from age- and sex-matched healthy controls. Results: Transient alterations were observed in the percentages and absolute numbers of NK cells in patients with infection active episodes. We also described five patients with stable disturbances in the distribution of NK cell subpopulations. These defects are mainly due to a decrease in the CD56 dim CD16 bright cells in peripheral blood. In addition, NK cell function abnormalities were observed in some patients, however, those were always transient and mainly associated to active disease. Conclusions: These findings demonstrate transient alterations in the percentages and absolute numbers of NK cells in patients with recurrent or severe infection. Also, stable disturbances in CD56 dim CD16 bright NK cells are observed in these patients. Nevertheless, these parameters must be thoroughly studied to determine the mechanisms that entail these immune abnormalities and investigate how they alter the immune response.

Preparation and cytotoxicity evaluation of chitosan-sodium alginate composite gel / 中国组织工程研究

BACKGROUND:Sodium alginate and chitosan are the polycation and polyanion natural polymer materials respectively, and they can be crosslinking agents complementing each other to form composite gel and avoid the cytotoxicity resulting from some common crosslinking agents . OBJECTIVE:To prepare the chitosan-sodium alginate composite gel and evaluate its cytotoxicity in vitro. METHODS:Chitosan was dissolved in 0.25 mol/L acetic acid to make a 30 g/L mass concentration solution, and 0.1 mol/L NaOH solution was added to neutralize its acidity. Neutralization of the chitosan solutions leads to the formation of a precipitate in ultrasmal particles. Then the chitosan and 3%sodium alginate solution in deionized water were mixed in 1:1 volume ratio by high frequency oscil ating to produce composite gel. The composite gel were detected by scanning electron microscopy and Fourier transform infrared spectrometry after freeze-drying. The 24-hour and 72-hour leaching solutions of composite gel, 24-hour and 72-hour leaching solutions of polyethylene and phenol solution were added to the L-929 cells’ culture medium respectively in order to evaluate the cytotoxicity of composite gel in vitro. RESULTS AND CONCLUSION:The results of Fourier transform infrared spectrometry showed the variation of characteristic peak values of composite gel which were different from sodium alginate and chitosan;and under scanning electron microscope, a spatial network structure formed with abundant intervals. Result of the cytotoxicity valuation was qualified for the chitosan-sodium alginate composite gel. These findings indicate that the chitosan-sodium alginate composite gel can be used as tissue engineering scaffold materials.

Expression and cytotoxic effect of transmembrane form of human blood group A antigen mimotope vaccine in a malignant melanoma cell line B16 / 中华皮肤科杂志

Objective To establish a stable cell line expressing transmembrane form of human blood group A antigen mimotope vaccine by transfecting malignant melanoma cell line B16, and to detect the cytotoxicity of the vaccine against melanoma cells. Methods Cultured B16 cells were classified into 4 groups, i.e.,P/F-M-pIRES group [transfected with the recombinant plasmid mimotope peptide/Fas-macrophage inflammatory protein (Mip)-pIRES], P/F-pIRES group (transfected with the recombinant plasmid mimotope peptide/FaspIRES), M-pIRES group (transfected with the recombinant plasmid Mip-pIRES), and pIRES group (transfected with the empty plasmid pIRES). B 16 cells were transfected through Lipofectamine 2000. Subsequently, RT-PCR and Western blotting were performed to detect the mRNA and protein expressions of the mimotope peptide/Fas fusion gene and Mip3β in transfected B16 cells. Cell counting kit-8 (CCK-8) was used to evaluate the vaccinemediated complement dependent cytotoxicity (CDC) and antibody-dependent cell-mediated cytotoxicity (ADCC)against B16 cells. Results RT-PCR yielded specific DNA fragments with expected size. Western blotting revealed the anti-A antibody-binding activity of the recombinant mimotope peptide/Fas fusion protein. Factor analysis indicated significant differences in CDC (F = 244.522, P ＜ 0.01 ) and ADCC (F = 71.593, P ＜ 0.01 )against B16 cells between the 4 groups. Group comparisons demonstrated more intense CDC and ADCC in P/FM-pIRES and P/F-pIRES groups compared with M-plRES and pIRES groups, stronger ADCC in P/F-M-pIRES group in comparison with P/F-pIRES group (F = 15.42, P ＜ 0.05), but no significant difference in CDC was observed between M-pIRES and pIRES group. Conclusions The transmembrane form of human blood group A antigen mimotope vaccine could be stably expressed in B16 cells, and mediate ADCC and CDC against B16 cells in vitro.

Basic sieving of an injectable prosthetic nucleus pulposus by studying cytotoxicity in vitro / 中华骨科杂志

To sieve a new type of polyether polyurethane as an injectable prosthetic nucleus pulpous through testing the cytotoxicity in vitro.Methods Five experimental groups were set as following:that samples 1,2,3 groups were polyether-polyurethane polymerized of different ratio of soft and hard segment with different catalysts; group 4 was polyether polyurethane polymerized slowly at 37 ℃ without catalyst; group 5was polyether polyurethane that toxic monomer responded completely.Additionally,a control group of culture medium was set without material extracts.Get 0.6 mg from each sample product and make into material extracts after disinfection,then dilution them by 50% and culture the mouse fibroblasts(cell L929)until 3 d,4d,5 d,by Adopting 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl tetrazolium bromide(MTT)colorimetric method to compare the 490 nm OD between the materials and control groups obtained by enzyme linked immune analysis,calculate the RGR of cells,and then evaluating the cytotoxicity of the materials.Results The RGR of L929 cell in group 4 and group 5 have no significant difference compared to the control group.Cytotoxic levels were 0 to 1; difference of the RGR of L929 cell between group 1-3 and control group were statistically significant.Cytotoxic levels were 1 to 2,but the cell morphology was normal.Conclusion The material polymerized without catalyst does not show cytotoxicity,and has great potential to be used as a substitute for nucleus pulposus.The cytotoxicity of the materials polymerized with catalyst needs to be tested more.

B-cell Complement Dependent Cytotoxic Crossmatch Positivity is an Independent Risk Factor for Long-term Renal Allograft Survival

The clinical significance of positive B-cell complement-dependent cytotoxicity crossmatching (B-CDC) in renal transplant recipients remains unclear. We reviewed 20 recipients with isolated B-CDC positivity at the time of transplantation. We compared the clinical characteristics, acute rejection and long-term graft survival between positive and negative B-CDC patients (n = 602). The number of retransplant recipients and positivity for T- and B-flowcytometric crossmatch was greater in positive B-CDC patients than in negative B-CDC patients. The overall acute rejection rate of positive B-CDC patients was significantly higher (P < 0.001), and Banff grade II or III cellular rejection was more frequently observed in positive B-CDC patients (P = 0.037). Compared with negative B-CDC patients, acute cellular rejection as a cause of graft loss was more prevalent (P = 0.020) and rescue rejection therapy was more frequently needed in positive B-CDC patients (P = 0.007). The allograft survival rate of positive B-CDC patients was significantly lower than that of negative B-CDC patients (P < 0.001), and B-CDC positivity independently increased the risk of allograft failure 2.31-fold (95% CI 1.15-4.67; P = 0.019) according to multivariate analysis. In conclusion, isolated B-CDC positivity is an independent long-term prognostic factor for allograft survival.

Expression of membrane inhibitor of reactive lysis in non-small cell lung carcinoma and its clinical significance / 中国基层医药

Objective To survey membrane inhibitor of reactive lysis(MIRL) expression in non-small cell lung careinoma(NSCLC) and to analyze the relationship between MIRL expression and clinical staging, adjuvant chemotherapy and disease-free survial. Methods The expression of MIRL in 8 adjacent tissues and 36 NSCLC sam-pies were determined by immunohistochemistry. Furthermore, the relationship between MIRL expression and clinical stage ,adjuvant chemotherapy and disease-free survival was assayed by follow-up. Results Among 36 samples of non-small-cell lung cancer,there were 10(27.8%) samples expressing MIRE. Out of 18 samples of squamous carcinoma, 4(22.2%) expressed MIRL,while 6(37.5%) expressed it in 16 samples of adenocarcinoma,there was no statistical significance between them(P>0.05). There were no expression in 2 samples of large cell carcinoma. There was no correlation between MIRL expression and disease-free survival(P>0.05). MIRL positive expression rate in patients with preoperational adjuvant chemotherapy was significantly lower than that of those without preoperational adjuvant chemotherapy(P<0.05). Conclusions There is great percentage of MIRE expression in NSCLC. Our present study suggests that the immunological inhibition of MIRL should be blocked when monoclonal antibody is used in the treat-merit of NSCLC.

Avaliação da citotoxidade de materiais odontológicos através do método de MTT e produção de óxido nítrico: descrição de uma técnica / Cytotoxicity citotoxicity of dental materials by the MTT assay and nitric oxide production: description of a technique

Introdução: Um dos problemas apresentados pelos materiais utilizados em Odontologia está associado à biocompatibilidade, já que poucos são totalmente inertes do ponto de vista biológico. Os materiais a serem usados em contato com tecidos humanos devem, portanto, ser testados com o objetivo de simular reações biológicas e ajudar no entendimento das respostas obtidas. Os estudos in vitro constituem a primeira etapa destes testes. A International Organization Standardization (ISO) e o Council on Dental Materials Instruments and Equipment of the American Dental Association recomendam o uso de uma bateria de testes in vivo e in vitro para estudar a biocompatibilidade dos materiais e, de acordo com as normatizações, a principal categoria de testes com este objetivo é a dos testes de biocompatibilidade. Dentre estes testes o protocolo MTT assay é um dos mais utilizados para se determinar a citotoxicidade de materiais de diversas naturezas sobre células em cultura. A citotoxicidade pode também estar relacionada às moléculas que, ao serem liberadas a partir de um determinado estímulo podem ocasionar danos aos tecidos. Estudos têm relatado a presença de uma molécula com potencial citotóxico, o óxido nítrico, em tecidos da cavidade bucal e seu envolvimento em doenças inflamatórias. Objetivo: Apresentação de uma metodologia de avaliação da citotoxicidade de materiais odontológicos através do método MTT e da análise da produção de óxido nítrico (NO), o qual está relacionado com a ação destes materiais na indução da resposta inflamatória. Conclusão: Verifica-se nesta metodologia que o ensaio de MTT pode ser facilmente adaptado para testes de citotoxicidade de materiais de diferentes composições e a mensuração da produção de óxido nítrico através do método de Griess fornece dados adicionais para a análise da citotoxicidade.