Waiting time for kidney transplantation based on calculated panel reactive antibodies: experience of a southern Brazilian center / Tempo de espera para transplante renal com base em painel de reatividade de anticorpos calculado: experiência de um centro do sul do Brasil

ABSTRACT Introduction: The aim of this study was to analyze the waiting list for kidney transplantation in our hospital according to candidate's panel reactive antibodies (cPRA) and its outcomes. Methods: One thousand six hundred forty patients who were on the waiting list between 2015 and 2019 were included. For the analysis, hazard ratios (HR) for transplant were estimated by Fine and Gray's regression model according to panel reactivity and HR for graft loss and death after transplantation. Results: The mean age was 45.39 ± 18.22 years. Male gender was predominant (61.2%), but the proportion decreased linearly with the increase in cPRA (p < 0.001). The distribution of patients according to panels were: 0% (n = 390), 1% - 49% (n = 517), 50% - 84% (n = 269), and ≥ 85% (n = 226). Transplantation was achieved in 85.5% of the sample within a median time of 8 months (CI 95%: 6.9 - 9.1). The estimated HRs for transplantation during the follow-up were 2.84 (95% CI: 2.51 - 3.34), 2.41(95%CI: 2.07 - 2.80), and 2.45(95%CI: 2.08 - 2.90) in the cPRA range of 0%, 1%-49%, and 50%-84%, respectively, compared to cPRA ≥ 85 (p < 0.001). After transplantation, the HR for graft loss was similar in the different cPRA groups, but the HR for death (0.46 95% CI 0.24-0.89 p = 0.022) was lower in the 0% cPRA group when adjusted for age, gender, and presence of donor specific antibodies (DSA). Conclusion: Patients with cPRA below 85% are more than twice as likely to receive a kidney transplantation with a shorter waiting time. The risk of graft loss after transplantation was similar in the different cPRA groups, and the adjusted risk of death was lower in nonsensitized recipients.

RESUMO Introdução: O objetivo foi analisar a lista de espera para transplante renal em nosso hospital segundo o painel de reatividade de anticorpos (PRAc) do candidato e seus desfechos. Métodos: Incluímos 1.640 pacientes em lista de espera entre 2015 e 2019. Para a análise, estimou-se a razão de risco (HR) para transplante pelo modelo de regressão de Fine e Gray conforme o painel de reatividade e HR para perda do enxerto e óbito após o transplante. Resultados: A idade média foi 45,39 ± 18,22 anos. Sexo masculino foi predominante (61,2%), mas a proporção diminuiu linearmente com o aumento do PRAc (p < 0,001). A distribuição de pacientes conforme os painéis foi: 0% (n = 390), 1% - 49% (n = 517), 50% - 84% (n = 269), e ≥85% (n = 226). O transplante foi realizado em 85,5% da amostra em tempo mediano de 8 meses (IC 95%: 6,9 - 9,1). As HRs estimadas para transplante durante o acompanhamento foram 2,84 (IC 95%: 2,51 - 3,34), 2,41 (IC 95%: 2,07 - 2,80) e 2,45 (IC 95%: 2,08 - 2,90) no intervalo de PRAc de 0%, 1%-49% e 50%-84%, respectivamente, comparadas com PRAc ≥ 85 (p < 0,001). Após o transplante, a HR para perda do enxerto foi semelhante nos diferentes grupos de PRAc, mas HR para óbito (0,46 IC 95% 0,24-0,89 p = 0,022) foi menor no grupo PRAc 0% quando ajustada para idade, sexo e presença de anticorpos doador específico (DSA). Conclusão: Pacientes com PRAc abaixo de 85% têm mais que o dobro de probabilidade de receber transplante renal com tempo de espera menor. Risco de perda do enxerto após o transplante foi semelhante nos diferentes grupos PRAc, e risco ajustado de óbito foi menor em receptores não sensibilizados.

Inmunización feto materna contra antígenos de HLA en mujeres de una población paraguaya / Fetomaternal immunization against HLA antigens in women from a Paraguayan population

El embarazo es la única causa natural de inmunización contra el sistema de Antígenos Leucocitarios Humano (HLA). Durante la gestación hay paso de leucocitos fetales a través de la placenta, lo que puede desencadenar en la madre una respuesta inmunológica contra los antígenos HLA fetales de origen paterno, con la consecuente producción de anticuerpos. El objetivo del estudio fue conocer la prevalencia de sensibilización a antígenos HLA inducida por embarazos en mujeres paraguayas y estudiar las características y especificidades de los anticuerpos encontrados. Realizamos un estudio descriptivo, prospectivo, de corte transversal de 319 mujeres paraguayas, que acudieron al Laboratorio Central de Salud Pública entre abril de 2017 y abril de 2018 utilizando la tecnología LUMINEX para la detección de anticuerpos anti- HLA. Se encontraron anticuerpos anti-HLA en 46% de las mujeres multíparas. Se detectaron anticuerpos contra todos los antígenos testados. La gran mayoría de los sueros resultaron ser poliespecíficos. Concluimos que al aumentar el número de gestas no solo aumenta la probabilidad de una mujer de desarrollar anticuerpos anti- HLA, sino que también parece aumentar la cantidad de especificidades desarrolladas y el título de los anticuerpos

Pregnancy is the only natural cause of immunization against the Human Leukocyte Antigen (HLA) system. During pregnancy, fetal leukocytes pass through the placenta, which can trigger an immunological response in the mother against the fetus paternal HLA antigens, with the consequent production of antibodies. The objective of this study was to determine the prevalence of pregnancy-induced HLA antigen sensitization in Paraguayan women and to study the characteristics and specificities of the antibodies found. We conducted a descriptive, prospective, cross-sectional study of 319 Paraguayan women, who attended the Central Laboratory of Public Health between April 2017 and April 2018 using LUMINEX technology to detect anti-HLA antibodies. We found anti-HLA antibodies in 46% of multiparous women. Antibodies against all tested antigens were detected. The vast majority of the sera exhibited multiple specificities. We conclude that increasing the number of gestations not only increases a woman's likelihood of developing anti-HLA antibodies, but it also appears to increase the number of developed specificities and titers of antibodies

Caracterización de los anticuerpos anti-HLA en posibles receptores cubanos de trasplante cardiaco / Characterization of anti-HLA antibodies in Cuban possible receptors of heart transplant

Introducción: En la supervivencia del corazón trasplantado son de importancia el empleo de los anticuerpos contra el sistema principal de histocompatibilidad (anticuerpos anti-HLA). Hace seis años se introdujo en Cuba el porcentaje de anticuerpos anti-HLA frente a panel (PRA) por método de ensayo de inmunoabsorción ligado a enzima (ELISA) como parte de las pruebas de compatibilidad pretrasplante de los receptores de trasplante cardiaco. Objetivo: Caracterizar los anticuerpos anti-HLA en pacientes receptores cubanos de trasplante cardiaco. Métodos: Entre septiembre de 2013 y abril de 2017 se les realizó el PRA por ELISA a 38 muestras de pacientes recibidas en el laboratorio de histocompatibilidad del Instituto de Hematología e Inmunología. Se utilizó la comparación de proporciones para el análisis estadístico. Resultados: El 47,4 por ciento de los pacientes estudiados presentó anticuerpos anti-HLA, fueron los más frecuentes los de clase I. La proporción de pacientes con PRA del 0 por ciento fue mayor en PRA clase II que en I (p: 0,0027). Mientras que fue mayor la proporción de pacientes con PRA clase I entre el 20 y el 75 por ciento (p: 0,0046). El 77,8 por ciento de los pacientes tuvo un PRA clase I mayor al 10 por ciento y en el PRA clase II alcanzó el 80 por ciento. Conclusiones: El porcentaje de anticuerpos anti-HLA frente a panel por método de ensayo de inmunoabsorción ligado a enzima permitió una mejor caracterización de los anticuerpos anti-HLA, lo que contribuyó a mejorar la compatibilidad en este tipo de paciente(AU)

Introduction: In survival after heart transplantation, the use of antibodies against the main histocompatibility system (anti-HLA antibodies) is important. Six years ago, the percentage of anti-HLA antibodies against panel (PRA) by enzyme-linked immunosorbent assay (ELISA) method was introduced in Cuba as part of the pre-transplant compatibility tests of heart transplant recipients. Objective: To characterize anti-HLA antibodies in Cuban heart transplant recipients. Methods: Between September 2013 and April 2017, PRA by ELISA was performed on 38 patient samples received in the histocompatibility laboratory of the Institute of Hematology and Immunology. Comparison of proportions was used for statistical analysis. Results: 47.4 percent of the study patients presented anti-HLA antibodies; those in class were the most frequent. The proportion of patients with PRA of 0 percent was higher in PRA class II than in class I (p=0.0027). The proportion of patients with PRA class I was greater, accounting for 20-75 percent (p=0.0046). 77.8 percent of the patients had a class I PRA greater than 10 percent, while in class II PRA it reached 80 percent. Conclusions: The percentage of anti-HLA antibodies versus a panel of enzyme linked immunosorbent assay method allowed better characterization of anti-HLA antibodies, which contributed to improving compatibility in this type of patient(AU)

The miss rate analysis of anti-HLA antibodies detection for kidney transplantation preoperative recipients with sensitization history based on luminex xMAP / 中华器官移植杂志

Objective To interrogate the detection of anti-HLA antibodies using two methods of Luminex xMAP,and to compare their detection capacity and to analyze their misdetection rate for initial screening,providing more accurate results in clinical practice.Methods 214 serum samples from recipients with a history of sensitization before renal transplantation were collected and detected by LM (LABScreen Mixed) and LSA (LABScreen Single Antigen) respectively on the Luminex xMAP platform.Results For the LM detection,the positive rates of anti-HLA class Ⅰ and Ⅱ were 50.9％ and 23.4％ respectively,which were lower than those used by the LSA detection (58.9％ and 46.7％ respectively).The difference had statistical significance (P ＜ 0.05).The sensitivity,specificity,miss rate and mistake rate of anti-HLA class Ⅰ and Ⅱ[detection were 80.2％,90.9％,19.8％,9.1％ and 49.0％,99.1％,51.0％,0.9％ respectively.The missed detection gene with the highest rate was Cw * 17:01,B * 15:12,B * 45:01 for anti-HLA class Ⅰ and DPA1 * 01:03,DPB1 * 06:01,DPA1 * 01:03,DPB1 * 01:01 for anti-HLA class Ⅱ.The highest MFI value was 10603 and 3659.For the recipients with only blood transfusion history or pregnancy history,LM and LSA detection showed no statistically significant difference when detecting anti-HLA class Ⅰ antibodies,but had statistically significant difference when testing anti-HLA class Ⅱ antibodies.For the patients with history of both blood transfusion and pregnancy history,LM and LSA showed no significant difference in the detection of anti-HLA class Ⅰ antibodies and anti-HLA class Ⅱ antibodies.The miss rate of anti-HLA class Ⅰ antibody detection was lower than that of anti-HLA class Ⅱ antibody detection.Conclusion LSA detection has the higher sensivity and lower miss rate than LM detection.In the light of the disadvantage of LM detection as diagnostic preliminary screening,it is suggested that LSA detection should be used directly for the recipients with a history of sensitization.By this process optimization,it is more likely to cause missent inspection and the occurrence of rejection,as well as a poor long-term survival rate.

Anticuerpos anticitomegalovirus y anti-virus de Epstein Barr pretrasplante renal en Cuba / Renal pretransplant anti-citomegalovirus and anti-Epstein Barr virus antibodies in Cuba

Introducción: las infecciones virales postrasplante de órganos sólidos constituyen las principales causas de morbilidad y mortalidad de los pacientes trasplantados. En Cuba se introdujo recientemente la detección de anticuerpos clase IgM e IgG, antivirus de Epstein Barr (EBV) y anticitomegalovirus (CMV) mediante técnicas de ELISA con analizador automático como parte del aseguramiento pretrasplante renal. Objetivo: determinar la prevalencia de las infecciones en los pacientes en espera de trasplante renal y si existe asociación entre la presencia de anticuerpos anti-EBV y anti-CMV con posibles eventos sensibilizantes y la presencia de anticuerpos anti-HLA. Métodos: se estudiaron 1 179 muestras de pacientes en espera de trasplante renal, entre agosto de 2013 y diciembre de 2014. Se realizaron 4 técnicas de inmunoensayos enzimáticos (ELISA) de tipo heterogéneo, no competitivo, cuantitativo e indirecto usando los estuches comerciales: Cytomegalovirus IgG ELISA, Cytomegalovirus IgM ELISA, Epstein-Barr virus VCA IgG y Epstein-Barr virus VCA IgM. El estado de aloinmunizacion anti-HLA clase I y II se definió de acuerdo a los estudios realizados por ELISA con los estuches comerciales: LIFECODES QuikScreen y LIFECODES B-Screen. Se empleó el estadígrafo Chi cuadrado de independencia para determinar la existencia de asociación entre la presencia de anticuerpos y el sexo, las transfusiones sanguíneas, trasplantes previos, hepatitis B, C y anticuerpos anti-HLA. Resultados: la prevalencia de infección con estos virus fue semejante en sujetos sanos y pacientes en espera de trasplante renal. Existió asociación entre IgM anti-CMV, IgG anti-CMV y IgM anti-EBV con el sexo, e IgG anti-CMV con las transfusiones, la seropositividad para la hepatitis C y los anticuerpos anti-HLA clase I. Conclusiones: se hace necesario tomar medidas para evitar el contagio peritrasplante por transmisión sanguínea de los pacientes seronegativos a estos virus pues debido a la inmunosupresión que provocan constituyen un riesgo para el éxito del trasplante renal(AU)

Introduction: Solid organ post-transplant viral infections are the main cause of worldwide morbi-mortality in transplanted patients. In Cuba it has been recently introduced the IgM and IgG anti Epstein Barr (EBV) and anti Citomegalovirus (CMV) antibody detection by ELISA with automatic analyzers as part of the pre transplant studies. Objective: to know population viral infection prevalence and to find possible association between anti EBV and anti CMV antibodies with sensitizing events and anti-HLA antibodies. Methods: An, investigation was carry out using 1179 samples from patients waiting for renal transplant at the Institute of Hematology and Immunology since August 2013 to December 2014. Four enzyme immunoassay (ELISA) heterogeneous type, non-competitive, quantitative and indirect were performed using commercial kits: Cytomegalovirus IgG ELISA, IgM ELISA Cytomegalovirus, Epstein-Barr virus VCA IgG and Epstein-Barr virus VCA IgM. Alloimmunization state anti-HLA class I and II are defined according to studies by ELISA with commercial kits: LIFECODES QuikScreen and LIFECODES B-Screen. Chi square test of independence was used to determine the existence of association between the presence of antibodies and sex, blood transfusions, previous transplantation, hepatitis B, C and anti-HLA antibodies. Results: It was found that the viral infection prevalence was the same as other populations, association of IgM anti CMV, IgG anti CMV and IgM anti EBV with sex and IgG anti CMV with blood transfusions, hepatitis C seropositivity and anti-HLA clase I antibodies. Conclusions : It is necessary to take measures to avoid peritransplant contagion of seronegative patients to theseviruses by blood transmission due to the immunosuppression that they cause, in order to obtain a renal transplant success(AU)

Características de los pacientes en espera de trasplante renal / Characteristics of patients waiting for kidney transplantation

Los pacientes con insuficiencia renal crónica presentan un marcado descenso de la tasa de filtración glomerular por lo que requieren de terapia de reemplazo renal como la diálisis o el trasplante para sobrevivir. El objetivo del estudio fue determinar las características de los pacientes en lista de espera para trasplante renal. Analizamos 156 pacientes provenientes de diversos centros de diálisis que acudieron al Laboratorio Central de Salud Pública entre julio de 2.013 y agosto de 2.014. Se recolectaron datos demográficos y muestras de sangre para determinar la presencia de anticuerpos anti-HLA por ELISA. Las edades estaban comprendidas entre 4 y 74 años, con un promedio de 40 años. Se registraron pacientes de 15 de las 18 Regiones Sanitarias del país, 50% de los cuales provenían de Asunción y del Departamento Central. La cobertura médica se encontró dividida en partes iguales entre el Ministerio de Salud Pública y el Instituto de Previsión Social. El tiempo promedio en diálisis fue de 34 meses, el 66% de los pacientes fueron poli-transfundidos, el 13% candidatos a retrasplante y el 34% de las mujeres fueron multíparas. El 36% de la población estudiada presentó anticuerpos anti-HLA. Se concluye que los pacientes en espera de trasplante renal se caracterizan por encontrarse en plena edad productiva y por permanecer en diálisis durante varios años. Además, un tercio de esta población se encuentra inmunizada frente a antígenos de histocompatibilidad, lo que dificulta su acceso al trasplante.

Patients with chronic renal failure present a pronounced reduction of the glomerularfiltration rate and therefore, require renal replacement therapy such as dialysis or kidneytransplantation to survive. The aim of this study was to determine the characteristics ofpatients on the waiting list for kidney transplantation. We analyzed 156 patients fromvarious dialysis centers who came to the Central Laboratory of Public Health betweenJuly, 2013 and August, 2014. Demographic information and blood samples were collectedto determine the presence of anti-HLA antibodies by ELISA. Ages were between 4 and 74years, with a mean of 40 years. There were patients from 15 of the 18 health regions ofthe country, 50% of them came from Asunción and the Central Department. Medicalcoverage was found to be divided in equal parts between the Ministry of Public Health andthe Social Security Institute. The mean time on dialysis was 34 months, 66% of thepatients had received multiple blood transfusions, 13% of them were candidates for asecond transplant, and 34% of the women were multiparous. Thirty six percent of thestudied population presented anti-HLA antibodies. The results of this study indicate thatpatients awaiting kidney transplantation in Paraguay are characterized by being at theirproductive age and remain on dialysis for several years. In addition, a third of this population is immunized against histocompatibility antigens, which hinders their access totransplantation.

Anticuerpos contra células del trofoblasto en el primer trimestre del embarazo / Antibodies against trophoblast cells in the first quarter of pregnancy

Las células del trofoblasto no expresan los antígenos HLA clásicos de clase I (A, B, C), pero sí los antígenos HLA G que pueden generar anticuerpos capaces de tener reacción cruzada con los primeros. Se estudiaron 24 mujeres en el primer trimestre del embarazo, sin antecedentes de embarazos o transfusiones de sangre, con anticuerpos reactivos contra leucocitos, plaquetas o ambos (9 antigranulocitarios y 15 anti-HLA), para determinar la presencia de anticuerpos antitrofoblasto, mediante técnica de inmunofluorescencia indirecta en lámina. El 54,16 por ciento presentó anticuerpos antitrofoblasto. El 86,66 por ciento de las embarazadas con anticuerpos anti-HLA, presentó anticuerpos contra trofoblasto, mientras que ninguno de los sueros con anticuerpos específicos de granulocitos reaccionó con las células trofoblásticas (p=0,00). Después de la adsorción con tejido trofoblástico, los sueros con anticuerpos con especificidad granulocitaria mantuvieron la reactividad con leucocitos de sangre periférica, y solo 2 de los que presentaban especificidad HLA. Los resultados sugieren que la mayoría de los anticuerpos anti-HLA, reactivos con leucocitos, plaquetas o ambos, pueden estar dirigidos contra antígenos HLA-G del trofoblasto y muestran reacción cruzada con los antígenos HLA leucocitarios, lo cual favorece el bloqueo de la respuesta de los leucocitos maternos contra las células fetales, lo que pudiera explicar, además, la alta prevalencia de anticuerpos anti-HLA en el embarazo temprano

Trophoblast cells do not express classical HLA class I antigens (A, B, C), but they do express HLA G antigens which may generate antibodies capable of cross-reacting with the former. A study was conducted of 24 women in the first quarter of pregnancy, with no previous pregnancies or blood transfusions, with reactive antibodies against leukocytes, platelets or both (9 antigranulocytary and 15 anti-HLA), to determine the presence of antitrophoblast antibodies, by plate indirect immunofluorescence technique. 54.16 percent had antitrophoblast antibodies. 86.66 percent of the pregnant women with anti-HLA antibodies had antibodies against the trophoblast, whereas none of the sera with granulocyte specific antibodies reacted with trophoblastic cells (p=0,00). Following adsorption with trophoblastic tissue, the sera with antibodies showing granulocyte specificity remained reactive with peripheral blood leukocytes, as opposed to just 2 of those showing HLA specificity. Results suggest that most anti-HLA antibodies reactive with leukocytes, platelets or both, may be aimed against trophoblast HLA-G antigens, and cross-react with leukocyte HLA antigens, which facilitates blockage of the response of maternal leukocytes against fetal cells. This may also explain the high prevalence of anti-HLA antibodies during early pregnancy

Analysis of Positive Flow Cytometric Crossmatch in Organ Transplantation

BACKGROUND: Pretransplant HLA crossmatch is one of the most important parts in solid organ transplantation. Flow cytometic crossmatch (FCXM) is more sensitive than anti-human globulin enhanced complement dependent lymphocytotoxicity (AHG-CDC) in detecting anti-HLA antibodies. We compared the results of the two methods and analyzed the FCXM-positive cases in various aspects. METHODS: Sera from 212 patients were tested for the detection of anti-HLA antibodies by FCXM and 188 of them were also tested by AHG-CDC assay. The results were analyzed in relation to their histories of pregnancy, transfusion or organ transplantation and also according to the donor patient relationships. We compared the FCXM results obtained before and after desensitization therapy (using plasmapheresis and anti-CD20 antibody) in 5 sensitized patients. RESULTS: Concordance of the results between the two methods was 88.8% (167/188). FCXM results correlated with history of pregnancy, but not with that of transfusion. When the patients were divided into 4 groups according to donor-patient relationships, the T cell FCXM mean fluorescence intensity (MFI) ratio (sample/control) was significantly higher in the husband-to-multiparous wife group compared to the other 3 groups (children-to-mother, unrelated donor-to-multipara, and the rests). After desensitization therapy, MFI ratios of T cell FCXM decreased and those of B cell FCXM increased, probably due to rituximab effect, in all 5 patients. CONCLUSIONS: FCXM using a MFI ratio, has a higher sensitivity than AHG-CDC in detection of donor specific antibodies. Also it can be useful in monitoring antibody levels during desensitization therapy.

The Frequency and Characteristics of the Platelet Refractoriness and Alloimmunization in Platelet Concentrate Multiple-Transfused Thrombocytopenic Patients / 대한혈액학회지

BACKGROUND: Understanding the cause for platelet refractoriness in a given patient is the critical step in determining the strategy for optimum management. The aim of this study was to establish the causes and frequency of platelet refractoriness as well as the incidence of anti- HLA antibodies and anti-platelet specific antibodies in multiple transfused thrombocytopenic patients. METHODS: Our study was based on 58 patients requiring platelet transfusions on at least three consecutive occasions from September 1997 to December 1997 in our hospital. The platelet refractoriness was defined as 18-24 hour post-transfusion corrected count increment (CCI) of less than 5,000. Enzyme immunosorbent assay (EIA), panel reactive antibody test (PRA) and Modified antigen capture ELISA (MACE) were applied for the detection of alloimmunization. RESULTS: Thirty-nine patients had episodes of refractoriness (67%). In 39 patients, poor response was seen in 38 patients (97%) with presence of non-immune factors known to be associated with platelet refractoriness. The total rate of alloimmunization was 31%, accounting for fourteen patients (24%) who had HLA antibodies, and four patients (7%) who had platelet specific antibodies. No patient had platelet-specific antibodies in addition to HLA antibodies. From our results, alloimmunization has shown a statistically meaningful relationship with CCI and the use of leukoreduction filtered blood components. CONCLUSION: Our data suggest that immune mechanisms are not the predominant cause of platelet refractoriness and HLA antibodies are produced separately with platelet-specific antibodies, as well as more frequently in alloimmunization.

Frequency of HLA antibodies in south India.

Sera from 4088 pregnant women (649 antenatal bleeding and 3439 post-partum bleeding) living in Madurai, were collected and screened for anti-HLA. Α, Β and DR antibodies. 696 of them were screened for anti-HLA DR antibodies. Ten per cent (65/649) of antenatal sera and 13·4% of post-partum sera (463/3439) were positive for HLA A and Β antibodies: nonetheless the percentage of monospecific sera were almost the same in both. Screening for HLA DR antibodies were carried out using platelet absorption in test tray technique: seventy three of 696 (10·5%) were positive. The incidence of anti-HLA A, B antibodies correlates to the allelic frequencies in the population. Thus in India, collection and screening post-partum haemorrhage is the simplest and cost effective method of acquiring polyclonal sera for routine laboratory and diagnostic use.