技术资料

Transfusion-related acute lung injury (TRALI) is a serious complication of transfusion and has been ranked as one of the leading causes of transfusion-related fatalities. Nonetheless,many details of the immunopathogenesis of TRALI,particularly with respect to recipient factors are unknown. We used a murine model of antibody-mediated TRALI in an attempt to understand the role that recipient lymphocytes might play in TRALI reactions. Intravenous injection of an IgG2a antimurine major histocompatibility complex class I antibody (34-1-2s) into BALB/c mice induced moderate hypothermia and pulmonary granulocyte accumulation but no pulmonary edema nor mortality. In contrast,34-1-2s injections into mice with severe combined immunodeficiency caused severe hypothermia,severe pulmonary edema,and approximately 40% mortality indicating a critical role for T and B lymphocytes in suppressing TRALI reactions. Adoptive transfer of purified CD8(+) T lymphocytes or CD4(+) T cells but not CD19(+) B cells into the severe combined immunodeficiency mice alleviated the antibody-induced hypothermia,lung damage,and mortality,suggesting that T lymphocytes were responsible for the protective effect. Taken together,these results suggest that recipient T lymphocytes play a significant role in suppressing antibody-mediated TRALI reactions. They identify a potentially new recipient mechanism that controls the severity of TRALI reactions. View Publication

IL-12 is an immunoregulatory cytokine,which promotes Th1 cell differentiation and is a major inducer of IFN-gamma. IFN-beta,a Type I IFN used in the treatment of multiple sclerosis,has been shown to significantly increase the expression of the anti-inflammatory cytokine IL-10,a major suppressor of Th1 cytokines. The beneficial immunomodulatory effects of IFN-beta may in part be a result of its ability to suppress IL-12. However,IL-12 and IFN-beta signal via the STAT4 pathway. Our aim was to investigate the relationship between IL-12 and IFN-beta by observing the effect of prior exposure to IL-12 or IFN-beta on the ability of T cells to subsequently respond to the other cytokine. We report that IFN-beta increases IL-12-induced STAT4 phosphorylation and up-regulates IL-12 receptor beta1 and beta2 expression. However,despite this up-regulation,IFN-beta suppressed IL-12-induced IFN-gamma expression. Our results suggest that this may be a result of the parallel induction of IL-10 by IFN-beta. View Publication

BACKGROUND/AIM Live attenuated vaccines confer partial protection in pigs before the appearance of neutralizing antibodies,suggesting the contribution of cell-mediated immunity (CMI). However,PRRSV-specific T-lymphocyte responses and protective mechanisms need to be further defined. To this end,the hypothesis was tested that PRRSV-specific T-lymphocytes induced by exposure to type-2 PRRSV can recognize diverse isolates. METHODS An IFN-gamma ELISpot assay was used to enumerate PRRSV-specific T-lymphocytes from PRRSVSD23983-infected gilts and piglets born after in utero infection against 12 serologically and genetically distinct type-1 and -2 PRRSV isolates. The IFN-gamma ELISpot assay using synthetic peptides spanning all open reading frames of PRRSVSD23983 was utilized to localize epitopes recognized by T-lymphocytes. Virus neutralization tests were carried out using the challenge strain (type-2 PRRSVSD23983) and another strain (type-2 PRRSVVR2332) with high genetic similarity to evaluate cross-reactivity of neutralizing antibodies in gilts after PRRSVSD23983 infection. RESULTS At 72 days post infection,T-lymphocytes from one of three PRRSVSD23983-infected gilts recognized all 12 diverse PRRSV isolates,while T-lymphocytes from the other two gilts recognized all but one isolate. Furthermore,five of nine 14-day-old piglets infected in utero with PRRSVSD23983 had broadly reactive T-lymphocytes,including one piglet that recognized all 12 isolates. Overlapping peptides encompassing all open reading frames of PRRSVSD23983 were used to identify ≥28 peptides with T-lymphocyte epitopes from 10 viral proteins. This included one peptide from the M protein that was recognized by T-lymphocytes from all three gilts representing two completely mismatched MHC haplotypes. In contrast to the broadly reactive T-lymphocytes,neutralizing antibody responses were specific to the infecting PRRSVSD23983 isolate. CONCLUSION These results demonstrated that T-lymphocytes recognizing antigenically and genetically diverse isolates were induced by infection with a type 2 PRRSV strain (SD23983). If these reponses have cytotoxic or other protective functions,they may help overcome the suboptimal heterologous protection conferred by conventional vaccines. View Publication

Gag-specific CD4 proliferative responses correlate inversely with HIV-1 RNA levels in infected adults,and robust responses are characteristic of long-term nonprogressive infection. However,strong responses are seldom detected in adult subjects with progressive infection and are not generally reconstituted on highly active antiretroviral therapy (HAART). To date,the role of HIV-1-specific Th responses in children has not been thoroughly examined. We characterized Gag-specific CD4 responses among 35 perinatally infected subjects,including 2 children who spontaneously control viremia without antiretroviral therapy,21 children with viral loads (VL) of textless400 on HAART,and 12 viremic children. Gag-specific Th activity was assessed by lymphoproliferative assay,and responses were mapped using overlapping Gag peptides in an IFN-gamma ELISPOT. Robust proliferative responses were detected in the children exhibiting spontaneous control of viremia,and mapping of targeted Gag regions in one such subject identified multiple epitopes. Among children textgreateror=5 years old,14 of 17 subjects with VL of textless400 on HAART demonstrated a significant p24 proliferative response (median p24 stimulation index,20),in contrast with only 1 of 9 viremic children (median p24 stimulation index,2.0; p = 0.0008). However,no subject younger than 5 years of age possessed a significant response,even when viremia was fully suppressed. When compared with adults with VL of textless400 on HAART,Th responses among children with VL of textless400 were both more frequent (p = 0.009) and of greater magnitude (p = 0.002). These data suggest that children may have a greater intrinsic capacity to reconstitute HIV-1-specific immunity than adults,and may be excellent candidates for immune-based therapies. View Publication

Regulatory T cells (Tregs) are a suppressive subset of CD4(+) T lymphocytes implicated in the prevention of acute GVHD (aGVHD) after allo-SCT (ASCT). To determine whether increased frequency of Tregs with a skin-homing (cutaneous lymphocyte Ag,CLA(+)) or a gut-homing (α(4)β(7)(+)) phenotype is associated with reduced risk of skin or gut aGVHD,respectively,we quantified circulating CLA(+) or α(4)β(7)(+) on Tregs at the time of neutrophil engraftment in 43 patients undergoing ASCT. Increased CLA(+) Tregs at engraftment was associated with the prevention of skin aGVHD (2.6 vs 1.7%; P=0.038 (no skin aGVHD vs skin aGVHD)),and increased frequencies of CLA(+) and α(4)β(7)(+) Tregs were negatively correlated with severity of skin aGVHD (odds ratio (OR),0.67; 95% confidence interval (CI),0.46-0.98; P=0.041) or gut aGVHD (OR,0.93; 95% CI,0.88-0.99; P=0.031),respectively. This initial report suggests that Treg tissue-homing subsets help to regulate organ-specific risk and severity of aGVHD after human ASCT. These results need to be validated in a larger,multicenter cohort. View Publication