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.

The impact of donor-specific anti-human leukocyte antigen antibodies in salvage haploidentical hematopoietic cell transplantation with posttransplant cyclophosphamide in patients with nonmalignant disorders.

The presence of donor-specific anti-human leukocyte antigen (HLA) antibodies (DSAs) has been recognized as a major risk factor for graft failure (GF) after haploidentical hematopoietic cell transplantation with posttransplant cyclophosphamide (haplo-PTCy). However, the role of DSAs in salvage haplo-PTCy for rescuing patients with nonmalignant disorders (NMDs) has not yet been reported. The present study retrospectively analyzed 22 patients with NMDs who underwent salvage haplo-PTCy from January 2008 to December 2017. The median age at the time of the rescue haplo-PTCy was 9 years (range, 1-26 years). Median time from the first transplant to second haplo-PTCy was 56 days (range, 37-591 days). Among all patients, six (27.3%) had DSAs, with a median DSA strength (mean fluorescence intensity [MFI]) of 5201 (range, 1412-11,543) in the first DSA testing. In addition, the median DSA MFI was 2672 (range, 832-10,498) before the bone marrow infusion. Overall, GF occurred in 5 (25%) of the 20 assessable patients. Three of four (75%) patients with DSAs experienced GF versus 2 of 16 (12.5%) DSA-negative patients (P = 0.032). The median DSA MFI for patients with GF was 6437 (range, 1412-10,498) versus 1845 (range, 832-2672) for those who engrafted or had early death (P = 0.030). One-year event-free survival was significantly lower in DSA-positive patients than in those without DSAs (16.7% vs. 62.5%, P = 0.002). DSA-negative patients had an acceptable 1-year survival of 62.5%. In conclusion, this study suggests that DSAs may be associated with deleterious outcomes after salvage haplo-PTCy in patients with NMDs.

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)

Anti-HLA Class II Antibodies Correlate with C-Reactive Protein Levels in Patients with Rheumatoid Arthritis Associated with Interstitial Lung Disease.

The pathogenesis of Rheumatoid Arthritis (RA) is not fully understood, probably influenced by genetic and environmental factors. Interstitial Lung Disease (ILD) is an extra-articular manifestation of RA, which contributes significantly to morbidity and mortality. The identification of anti-HLA antibodies has been useful in the transplantation field; however, its contribution to autoimmune diseases as RA has not been fully studied. We aimed to determine the presence of anti-HLA antibodies in RA patients with and without ILD and its possible association with clinical and biochemical markers. One-hundred and forty-seven RA patients, of which 65 had ILD (RA-ILD group), were included. Sera samples for Anti-HLA Class II LABScreen panel-reactive antibodies (PRA) were analyzed. In both groups, women predominated, and lung function was worse in patients with ILD. The anti-CCP+ (UI/mL) was higher in the RA group in comparison to RA-ILD (p < 0.001). Expositional risk factors (tobacco smoking and biomass-burning smoke) were higher in RA-ILD patients. PRA+ was identified in ~25% RA-ILD patients, while ~29% in the RA group. The CRP levels have a positive correlation with the percentage of reactivity (%PRA, p = 0.02, r2 = 0.60) in the RA-ILD group. In conclusion, anti-HLA antibodies correlate with C-reactive protein levels in RA patients with ILD.

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.

Dynamics of anti-human leukocyte antigen antibodies after renal transplantation and their impact on graft outcome.

The purpose of this study was to sequentially monitor anti-HLA antibodies and correlate the results with antibody-mediated rejection (AMR), graft survival (GS), and graft function (GF). We collected sera from 111 kidney transplant recipients on transplant days 0, 7, 14, 30, 60, 90, 180, and 360 and analyzed PRA levels by ELISA. DSAs were analyzed by single-antigen beads in rejecting kidneys. At pre-transplant, 79.3% of the patients were non-sensitized (PRA = 0%) and 20.7% were sensitized (PRA > 1%). After transplant, patients were grouped by PRA profile: no anti-HLA antibodies pre- or post-transplant (group HLApre-/post-; n = 80); de novo anti-HLA antibodies post-transplant (group HLApre-/post+; n = 8); sensitized pre-transplant/increased PRA post-transplant (group HLApre+/post↑; n = 9); and sensitized pre-transplant/decreased PRA post-transplant (group HLApre+/post↓; n = 14). De novo anti-HLA antibodies were detected at 7-180 d. In sensitized patients, PRA levels changed within the first 30 d post-transplant. Incidence of AMR was higher in HLApre-/post+ and HLApre+/post↑ than in HLApre-/post-, and HLApre+/post↓ (p < 0.001) groups. One-yr death-censored GS was 36% in group HLApre+/post↑, compared with 98%, 88% and 100% in groups HLApre-/post-, HLApre-/post+, and HLApre+/post↓, respectively (p < 0.001). Excluding first-year graft losses, GF and GS were similar among the groups. In conclusion, post-transplant antibody monitoring can identify recipients at higher risk of AMR.

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