RESUMO
Background: Enhanced B-cell presentation of donor alloantigen relative to presentation of HLA-mismatched reference alloantigen is associated with acute cellular rejection (ACR), when expressed as a ratio called the antigen presenting index (API) in an exploratory cohort of liver and intestine transplant (LT and IT) recipients. Methods: To test clinical performance, we measured the API using the previously described 6-h assay in 84 LT and 54 IT recipients with median age 3.3 y (0.05-23.96). Recipients experiencing ACR within 60 d after testing were termed rejectors. Results: We first confirmed that B-cell uptake and presentation of alloantigen induced and thus reflected the alloresponse of T-helper cells, which were incubated without and with cytochalasin and primaquine to inhibit antigen uptake and presentation, respectively. Transplant recipients included 76 males and 62 females. Rejectors were tested at median 3.6 d before diagnosis. The API was higher among rejectors compared with nonrejectors (2.2â ±â 0.2 versus 0.6â ±â 0.04, P value = 1.7E-09). In logistic regression and receiver-operating-characteristic analysis, API ≥1.1 achieved sensitivity, specificity, and positive and negative predictive values for predicting ACR in 99 training set samples. Corresponding metrics ranged from 80% to 88% in 32 independent posttransplant samples, and 73% to 100% in 20 independent pretransplant samples. In time-to-event analysis, API ≥1.1 predicted higher incidence of late donor-specific anti-HLA antibodies after API measurements in LT recipients (P = 0.011) and graft loss in IT recipients (P = 0.008), compared with recipients with API <1.1, respectively. Conclusions: Enhanced donor antigen presentation by circulating B cells predicts rejection after liver or intestine transplantation as well as higher incidence of DSA and graft loss late after transplantation.
RESUMO
BACKGROUND: Allospecific CD154+T-cytotoxic memory cells (CD154+TcM) predict acute cellular rejection after liver transplantation (LTx) or intestine transplantation (ITx) in small cohorts of children and can enhance immunosuppression management, but await validation and clinical implementation. METHODS: To establish safety and probable benefit, CD154+TcM were measured in cryopreserved samples from 214 children younger than 21 years (National Clinical Trial 1163578). Training set samples (n = 158) were tested with research-grade reagents and 122 independent validation set samples were tested with current good manufacturing practices-manufactured reagents after assay standardization and reproducibility testing. Recipient CD154+TcM induced by stimulation with donor cells were expressed as a fraction of those induced by HLA nonidentical cells in parallel cultures. The resulting immunoreactivity index (IR) if greater than 1 implies increased rejection-risk. RESULTS: Training and validation set subjects were demographically similar. Mean coefficient of test variation was less than 10% under several conditions. Logistic regression incorporating several confounding variables identified separate pretransplant and posttransplant IR thresholds for prediction of rejection in the respective training set samples. An IR of 1.1 or greater in posttransplant training samples and IR of 1.23 or greater in pretransplant training samples predicted LTx or ITx rejection in corresponding validation set samples in the 60-day postsampling period with sensitivity, specificity, positive, and negative predictive values of 84%, 80%, 64%, and 92%, respectively (area under the receiver operator characteristic curve, 0.792), and 57%, 89%, 78%, and 74%, respectively (area under the receiver operator characteristic curve, 0.848). No adverse events were encountered due to phlebotomy. CONCLUSIONS: Allospecific CD154+T-cytotoxic memory cells predict acute cellular rejection after LTx or ITx in children. Adjunctive use can enhance clinical outcomes.
Assuntos
Ligante de CD40/análise , Citometria de Fluxo , Rejeição de Enxerto/imunologia , Imunidade Celular , Testes Imunológicos/métodos , Intestinos/transplante , Transplante de Fígado/efeitos adversos , Linfócitos T Citotóxicos/imunologia , Doença Aguda , Adolescente , Área Sob a Curva , Biomarcadores/análise , Células Cultivadas , Criança , Pré-Escolar , Criopreservação , Feminino , Rejeição de Enxerto/prevenção & controle , Humanos , Imunidade Celular/efeitos dos fármacos , Memória Imunológica , Imunossupressores/uso terapêutico , Lactente , Intestinos/imunologia , Modelos Logísticos , Masculino , Análise Multivariada , Valor Preditivo dos Testes , Curva ROC , Reprodutibilidade dos Testes , Medição de Risco , Fatores de Risco , Linfócitos T Citotóxicos/efeitos dos fármacos , Fatores de Tempo , Resultado do Tratamento , Adulto JovemRESUMO
BACKGROUND: Alloreactive T-cell apoptosis may explain reduced immunosuppression requirements with proapoptotic immunosuppression and among rejection-free recipients. This possibility remains unproven. METHODS: Apoptotic (caspase-3+, cathepsin B+) and inflammatory (CD154+) T-cell subsets were evaluated before and after adding rabbit antithymocyte globulin (rATG) to mixed lymphocyte co-cultures between human leukocyte antigen-mismatched peripheral blood lymphocytes from healthy adults. In random samples from children with liver (LTx-20) and intestine (ITx-13) transplantation, apoptotic T cells were evaluated for association with rejection-free outcomes using the caspase-3 substrate, phiphilux. RESULTS: In mixed lymphocyte co-cultures between normal human peripheral blood lymphocytes, (1) frequencies of memory (M) and naive (N) Th and Tc, which expressed activated caspase-3, were enhanced most by the combination of allostimulation and rATG, than either stimulus alone. These findings were confirmed with antibody to activated caspase-3, phiphilux, and terminal deoxynucleotide transferase-mediated dUTP nick-end labeling (TUNEL) assay; (2) frequencies of Th subsets, which expressed activated cathepsin B, were similarly increased with combined stimulation. Tc seemed resistant to cathepsin B activation; (3) with increasing rATG concentrations, proportionately more allospecific CD154+T-cytotoxic memory cells (TcM) survived than TcM, resulting in relative enrichment of allospecific CD154+TcM. In random blood samples, phiphilux+T-cell subset frequencies were higher among 14 rejection-free LTx and ITx recipients and demonstrated a greater increase with ex vivo rATG pretreatment than 19 rejectors. In logistic regression analysis, phiphilux+TcM associated best with rejection-free outcomes with a sensitivity of 57% and a specificity of 89%. CONCLUSION: Rabbit antithymocyte globulin facilitates apoptosis of alloreactive T cells by means of caspase-3 activation, which may explain its steroid-sparing effect in pediatric liver and intestine recipients. Apoptotic susceptibility of T-cytotoxic memory cells, which resist cathepsin B activation, may distinguish rejection-free and rejection-prone liver recipients.
Assuntos
Soro Antilinfocitário/uso terapêutico , Apoptose/efeitos dos fármacos , Caspase 3/metabolismo , Rejeição de Enxerto/prevenção & controle , Imunossupressores/uso terapêutico , Intestinos/transplante , Transplante de Fígado , Subpopulações de Linfócitos T/efeitos dos fármacos , Biomarcadores/metabolismo , Ligante de CD40/metabolismo , Catepsina B/metabolismo , Células Cultivadas , Criança , Pré-Escolar , Técnicas de Cocultura , Citocinas/metabolismo , Relação Dose-Resposta a Droga , Ativação Enzimática , Feminino , Rejeição de Enxerto/imunologia , Rejeição de Enxerto/patologia , Sobrevivência de Enxerto/efeitos dos fármacos , Antígenos HLA/imunologia , Humanos , Memória Imunológica/efeitos dos fármacos , Transplante de Fígado/efeitos adversos , Teste de Cultura Mista de Linfócitos , Masculino , Transdução de Sinais/efeitos dos fármacos , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/patologia , Fatores de Tempo , Resultado do TratamentoRESUMO
BACKGROUND: The transcription factor, t-bet, promotes inflammatory polarization and intestinal homing of many inflammatory cells. In previous studies, the t-bet and granulysin genes were upregulated in peripheral blood before and after intestine transplantation (ITx) rejection, but not during rejection, possibly because of sequestration in allograft mucosa. Mucosal sequestration of t-bet and granulysin may also explain the presence of inflammatory CD14+ monocyte-derived macrophages (MDM) and immunoglobulin G+ B-cell lineage cells, and loss of mature non-inflammatory CD138+ plasma cells in allograft mucosa during ITx rejection in these previous studies. METHODOLOGY: T-bet-stained and granulysin-stained cells, MDM and CD138+ plasma cells were evaluated with immunohistochemistry in serial biopsies from 17 children, in whom changes in MDM and CD138+ plasma cells were observed previously. RESULTS: T-bet-positive mucosal cells were significantly higher in postperfusion (P = 0.035) and early posttransplant biopsies (P = 0.016) among rejectors, compared with nonrejectors. T-bet-positive cell counts per high-power field (hpf) were (a) positively correlated with MDM counts/hpf in postperfusion (Spearman r = 0.73; P = 0.01) and early posttransplant biopsies (r = 0.54, r = 0.046), and (b) negatively correlated with CD138+B-/pre-plasma cells in early posttransplant biopsies (r = 0.63, P = 0.038). T-bet expression in CD14+ monocytes, CD19+B cells, and several other leukocyte subsets was higher in random blood samples from two rejectors, compared with those from five normal human subjects and three nonrejectors. Scant granulysin-stained mucosal cells precluded additional evaluation of this cytotoxin and its role in ITx rejection. SIGNIFICANCE: The transcription factor, t-bet, primes ITx rejection, and associates with disrupted homeostatic relationships between innate and adaptive immune cells in the allograft mucosa during rejection.