Successive emergence of two CD 8 subsets in primary CMV infection of allograft recipients

Abstract Allograft recipients with cytomegalovirus (CMV) infection develop increased proportions of circulating CD8 lymphocytes. A longitudinal study of 11 kidney and 5 liver allograft recipients with primary CMV infection but no other aetiological factor to explain graft dysfunction revealed selective imbalances in peripheral blood CD8' T cell subsets. Initially, CMV viraemia was associated with elevated CD8+bright' T cell numbers and T cell activation. Activation markers fell to normal when viral cultures became negative (before the end of the 1st month). During the 2nd-6th months, most (12/16) patients continued to have high CD8⁺ T cell counts (1050–2900 CD8⁺ cells/mm3), comprising an uncommon CD8⁺ T cell subset, as 45–73% of CD8^{+ bright} lymphocytes were CD3⁺ and TCRαβ⁺ but were not stained by anti-CD28, CD11b, CD16, CD56 and CD57 antibody. Unexpectedly, CD 8⁺ CD 57⁺ T cells, a hallmark of CMV infection, did not appear until the 2nd-6th months of primary CMV infection, and their numbers increased progressively thereafter. They became the predominant CD8⁺ T cell subset after about 6 months of infection and their persistence for several (up to 4) years was strongly correlated ( r = 0.87) with expansion of CD8⁺ cells. Persistence of CD 8 lymphocytosis was, thus, directly related to the rate of expansion of an uncommon CD 8⁺CD 57^- subset and its progressive replacement by CD 8⁺CD 57 ⁺ T cells that were chronically elicited by CMV.     

Patterns of CD4/CD8 T-cell ratio in dialysis effluents predict the long-term outcome of peritonitis in patients undergoing peritoneal dialysis.

BACKGROUND: The peritoneal immune compartment is a microenvironment with a particular T-cell repertoire and susceptible to local inflammation. To clarify the role of T lymphocytes in peritoneal immunity, the changes in T-cell subpopulations in peritoneal dialysis effluents (PDEs), and their influence on the response to the treatment of peritonitis and on its prognosis were studied in patients undergoing long-term, continuous ambulatory peritoneal dialysis (CAPD). METHODS: A cohort of 36 patients treated with CAPD and who had histories of peritonitis were divided into a group with rapid and a group with delayed response to antibiotics, and were followed for 3 years. CD4/CD8 T-cell ratios, T-cell cytokine mRNA expression patterns and transforming growth factor-beta1 (TGF-beta1) concentrations were examined in PDE during bouts of peritonitis. The change in 4 h D/P creatinine during the peritoneal equilibration test (PET) between year 0 and year 3 was expressed as deltaD/P creatinine. RESULTS: The serial changes in T-cell subsets in PDE during peritonitis showed two patterns: (i) pattern 1, manifest as a progressive increase in the CD4/CD8 ratio, and associated with a rapid response to treatment; and (ii) pattern 2, manifest as a progressive decrease in the CD4/CD8 ratio, and associated with a delayed response to treatment. The major T-cell phenotypes in PDE during peritonitis were Th1-CD4(+) and Tc2-CD8(+), determined by cloning techniques, RT-PCR and double immunofluorescence staining. TGF-beta1 in the effluent was undetectable in pattern 1 after 7-8 days, but remained detectable at 2 weeks in pattern 2. Pattern 2 patients had a significantly greater decrease (deltaD/P creatinine: -0.198+/-0.086) in solute transport than pattern 1 patients (deltaD/P creatinine: -0.036+/-0.077, P<0.05). CONCLUSIONS: These results suggest that a progressive decrease of the CD4/CD8 ratio in PDE correlates with a persistent expression of TGF-beta1, and plays a pathogenetic role in the evolution of peritonitis, PET deterioration and peritoneal fibrosis. Therefore, patterns of CD4/CD8 T-cell ratio in PDE may predict clinical outcomes of peritonitis in CAPD patients.     

Monitoring of Human Cytomegalovirus-Specific CD4+ and CD8+ T-Cell Immunity in Patients Receiving Solid Organ Transplantation

Absolute and human cytomegalovirus (HCMV)-specific CD4+ and CD8+ T-cell counts were monitored in 38 solid organ (20 heart, 9 lung and 9 kidney) transplant recipients during the first year after transplantation by a novel assay based on T-cell stimulation with HCMV-infected autologous dendritic cells. According to the pattern of T-cell restoration occurring either within the first month after transplantation or later, patients were classified as either early (n = 21) or late responders (n = 17). HCMV-specific CD4+ and CD8+ T-cell counts were consistently lower in late compared to early responders from baseline through 6 months after transplantation. In addition, in late responders, while HCMV infection preceded immune restoration, HCMV-specific CD4+ restoration was significantly delayed with respect to CD8+ T-cell restoration. The number of HCMV-specific CD4+ and CD8+ T-cells detected prior to transplantation significantly correlated with time to T-cell immunity restoration, in that higher HCMV-specific T-cell counts predicted earlier immune restoration. Clinically, the great majority of early responders (18/21, 85.7%) underwent self-resolving HCMV infections (p = 0.004), whereas the great majority of late responders (13/17, 76.5%) were affected by HCMV infections requiring antiviral treatment (p = <0.0001). Simultaneous monitoring of HCMV infection and HCMV-specific T-cell immunity predicts T-cell-mediated control of HCMV infection.     

CD103免疫毒素在同种胰岛移植中的应用

目的 制备能体内杀伤CD103表达细胞的免疫毒素,观察其对同种胰岛移植排斥反应的影响.方法 将CD103抗体与植物毒素saporin耦联产生M290-SAP,以2 mg/kg剂量注入小鼠腹腔,实验分为磷酸盐缓冲液(PBS)、IgG-SAP、M290和M290-SAP组,用流式细胞术检测CD103阳性细胞的肖减,之后将M290-SAP应用于化学性糖尿病小鼠胰岛移植模型,观察胰岛有功能存活情况.结果 PBS、IgG-SAP和M290组,肠上皮内CD103+CD8+淋巴细胞占CD3+淋巴细胞的百分比分别为70.9%、68.4%和79.5%,而M290-SAP组几乎降至0;M290-SAP也杀灭了CD103+的胸腺细胞.M290-SAP组胰岛移植物存活时间(＞100 d,n=9),明显优于未处理组、IgG-SAP和M290组(均在20d内排斥)(P＜0.01).结论 M290-SAP消除CD103表达细胞能促进同种胰岛移植物长期存活.

Abstract：

Objective To develop an immunotoxin (M290-SAP) that selectively depleted CD103expressing cells in vivo and study the effect of M290-SAP on the pancreatic islet allograft rejection. Methods The CD103 antibody was conjugated with plant toxin (saporin) to produce M290-SAP. M290-SAP was intraperitoneally injected into mice at a dose of 2 mg/kg. The mice were divided into PBS, IgG-SAP,M290 and M290-SAP groups. CD103-positive cells were counted by flow cytometry. The islet allograft survival was observed in each treated group. Results The percentage of intestinal intraepithelial CD103 +CD8+ lymphocytes in total CD3 + lymphocytes was 70. 9%, 68.4% and 79. 5% in PBS, IgG-SAP and M290 groups, respectively, and that in M290-SAP group down to almost 0%. M290-SAP also abrogated the CD103+ thymocytes. Islet graft survival time was ( ＞ 100 days,n=9) in M290-SAP group, significantly longer than PBS group, IgG-SAP and M290 groups (islet allografts were rejected within 20 days) (P＜ 0. 01 ). Conclusion Elimination of CD103-expressing cells with M290-SAP can prolong long-term islet allograft survival.     

近交系大鼠肝移植自发免疫耐受模型的建立及其CD8+CD28-T细胞的作用

目的建立近交系大鼠原位肝移植自发免疫耐受模型,并研究CD8+CD28- T细胞在自发免疫耐受形成中的作用.方法双袖套法建立原位肝移植模型;流式细胞技术检测CD8+CD28- T抑制细胞含量变化;利用补体细胞毒和免疫磁珠方法分离CD8+CD28- T细胞,通过体外混合淋巴细胞反应验证其抑制功能.结果我们成功建立了BN(供体)LEW(受体)原位肝移植自发免疫耐受模型,并发现自发免疫耐受模型大鼠脾脏CD8+CD28- T细胞含量(23.7%±7.2%)显著高于正常大鼠(5.4%±1.5%)和急性排斥组大鼠(6.0%±1.3%),而且,分离纯化后的自发免疫耐受组大鼠脾脏CD8+CD28- T细胞可以抑制混合淋巴细胞反应的增殖,但急性排斥组大鼠脾脏CD8+CD28- T细胞无抑制功能.结论 BN(供体)LEW(受体)原位肝移植模型为自发免疫耐受;脾脏CD8+CD28- T细胞作为一种T抑制细胞,在自发免疫耐受的形成过程中具有重要作用.     

Characterization of CD3+CD4-CD8- (double negative) T cells reconstitution in patients following hematopoietic stem-cell transplantation

Background

CD3+CD4−CD8−double negative (DN) T cells, as a distinct subset of regulatory T cells (Tregs), played a pivotal role in patients following hematopoietic stem-cell transplantation.

Methods

This study examines the behavior of CD3+CD4−CD8− double negative (DN) T cells in 73 patients at days 30, 60, 90 and 180 after allo-HSCT.

Results

There was no significant difference in neutrophil and platelet engraftment between the higher and lower absolute counts of 30 days DN Tregs (p = 0.674, 0.863, respectively). The reconstitution of DN Tregs was significantly slower than that of CD8+, CD4+, and CD3+CD8+CD28− T cells (p < 0.001), but significantly faster than that of CD19+ and CD4+CD25+ T cells (p < 0.001, p = 0.032, respectively). Importantly, in the HLA mismatched group, DN Tregs reconstitution had significant effect on aGVHD (p = 0.027) and there was significant correlation between aGVHD and DN Tregs reconstitution (p = 0.035). DN Tregs reconstitution was significantly faster in the patients who were devoid of aGVHD than that of patients who developed aGVHD. Furthermore, we compared the absolute value of DN Tregs at 30 days, 60 days, 90 days and 180 days after allo-HSCT with grade aGVHD and found an inverse linear relationship in the HLA mismatched group (n = 37, P < 0.001, r = − 0.573).

Conclusions

The successful expansion of DN Tregs at 60 days after allo-HCST may help avoid severe manifestations of aGVHD in the HLA mismatched group, suggesting that DN Tregs have potential protection effect against aGVHD.     

Differential regulation of simultaneous antitumor and alloreactive CD8(+) T-cell responses in the same host by rapamycin

Rapamycin is an immunosuppressive agent routinely used in organ transplantation but also paradoxically exerts antiviral and antitumor activities. Pathogen-specific memory CD8(+) T-cell (T(CD8) ) responses were recently found to be augmented by rapamycin. However, whether rapamycin influences the magnitude and quality of anticancer T(CD8) responses is unknown. Importantly, how rapamycin may regulate simultaneous virus/tumor-specific and alloreactive T(CD8) in the same host remains unexplored. To answer these questions, we primed wild-type mice with allogeneic cells concomitantly expressing simian virus 40 large tumor antigen (T Ag), a viral oncoprotein with well-defined epitopes. Rapamycin selectively enhanced the cross-priming of T(CD8) specific for T Ag's most immunodominant epitope called site IV but not T(CD8) alloreactivity. Rapamycin-treated mice also had a high percentage of splenic CD127(high) KLRG1(low) T(CD8) and an increased frequency of site IV-specific T cells long after the peak of their primary response. When site IV was presented as a cytosolic minigene encoded by a recombinant vaccinia virus, rapamycin failed to boost the site IV-specific response. Therefore, the nature and presentation mode of antigen determine the susceptibility to the adjuvant effect of rapamycin. Our findings reveal the unexpected benefit of rapamycin treatment in recipients of allografts co-expressing tumor/viral Ags.     

Liver allograft rejection in rats depleted of CD8+ cells

The mechanism(s) of rejection or tolerance induction is a competitive, complex process that presumably involves interactions between multiple subpopulations of T lymphocytes. We investigated the roles of CD8⁺ cytolytic and CD4+ helper T cells in rat strains that tolerate liver allografts and that differ at both the major histocompatibility complex (MHC) (RT1) and minor histocompatibility genes. Orthotopic liver transplantation (OLT) with arterial reconstruction was performed with Brown Norway (BN) (RT1ⁿ) donors and Lewis (RT1¹) recipients, some of which were untreated, others treated with anti-CD8 antibody, and still others treated with anti-CD4 antibody. Liver graft rejection was monitored for 28 days on the basis of two criteria: (1) serum levels of AST enzyme at 3-day intervals and (2) liver biopsies at weekly intervals and at the time of sacrifice at the end of the study period. In the untreated control group, an elevation of AST was found to peak at day 6 after grafting, and it remained elevated until day 28 (AST 542±72 U/l). Histologically, signs of severe rejection were first observed on day 9; these changed to moderate rejection about day 21 and to mild rejection by day 28, when the animals were sacrificed. Recipients pre-treated with anti-CD8 demonstrated a significant elevation of AST within 6 days that, unlike in the control recipients, continued to rise sharply through the observation period (AST 1127±181 U/1, P=0.009 vs control group). Liver biopsies showed mild rejection at day 9 and moderate rejection at days 21 through 28. Recipients pretreated with anti-CD4 showed a time course of enzyme elevation and severity of rejection that was not significantly different from that observed in the control group. However, anti-CD4 treatment resulted in only 75% depletion of CD4⁺ cells in peripheral blood as compared to complete elimination of CD8⁺ cells following anti-CD8 treatment. Functional studies of spleen and liver-infiltrating lymphocytes obtained after 28 days showed low proliferative response in mixed lymphocyte culture with both BN and PVG stimulator spleen and lymph node cells. These results suggest that in this donor/recipient combination, removal of CD8⁺ cells increases the severity of rejection as demonstrated by a progressive rise in AST and histology. Moreover, OLT in this combination results in a profound, nonspecific inhibition of proliferative T-cell responses to MHC alloantigens.     

Functional CD25(bright+) alloresponsive T cells in fully immunosuppressed renal allograft recipients

BACKGROUND: Evidence from animal studies indicate a crucial role for CD25(bright+) regulatory T cells in transplantation tolerance. METHODS: To assess whether peripheral CD25(bright+) T cells control immune responses in immunosuppressed kidney transplant patients, we analyzed the suppressive capacities of these cells using mixed lymphocytes reactions. RESULTS: Allogeneic stimulation of patients peripheral blood mononuclear cells was associated with IL-2 production and T-cell proliferation. Depletion of CD25(bright+) T cells resulted in a 35% (median) higher IL-2 production and a 38% higher proliferative response against third party cells, showing that functional regulatory CD25(bright+) T cells were present (p = 0.03 and 0.02 respectively). In eight out of 11 patients, we also demonstrated regulation activity against donor-activated T cells (p = 0.03). These data were confirmed in coculture experiments with isolated CD25(-/dim) T cells plus CD25(bright+) T cells. At a 1:2 ratio, the CD25(bright+) T cells suppressed the proliferation of CD25(-/dim) donor- and third party-stimulated responder T cells. CONCLUSIONS: CD25(bright+) T cells with immune regulatory activities against anti-donor-responsive T cells are readily detectable in renal allograft recipients during treatment with full dosage immunosuppression. Whether CD25(bright+) T cells indeed play a role in graft acceptance after organ transplantation in patients remains to be elucidated.     

Apoptosis and CD8 and CD54 cell expression in rat small bowel transplantation

The importance of activated CD8 cells expressing IL-2R in small bowel and other organ rejection has been reported. Some authors even consider that a positive correlation might be demonstrated between the number of apoptotic enterocytes and the degree of graft rejection. In addition, moderate to intense activation of endothelial molecules in small bowel allograft in rats has been reported in chronic rejection. The aim of the present paper is to ascertain, in a heterotopic small bowel transplantation (HSBT) in rats, whether CD3, CD4, CD8, and CD54 cell expression in the allograft infiltrates shows some relationship with allograft enterocyte apoptosis when rejection is present. Wistar Furth male rats were allotted to two groups: group A was the control group without transplantation; group B received a heterotopic small bowel allograft from Fisher rats and an im dose of FK506 (0.25 mg/kg/day). A significant increase of CD8, CD54 cell receptor expression, and apoptosis in the group undergoing HSBT showed rejection. No significant differences have been observed in the variables under study between the control and HSBT without rejection groups or in CD3 and CD4 among the three groups. We observed a significant correlation between apoptosis and rejection, between CD8 and CD54 with apoptosis and with rejection, and between CD8 and CD54. This indicates that the activation of endothelial molecules and cells may play an important role in established HSBT chronic rejection. We consider that this study may contribute to the knowledge of small bowel allograft chronic rejection and its immunomodulation.     

CD154 Deficiency Uncouples Allograft CD8+ T‐Cell Effector Function from Proliferation and Inhibits Murine Airway Obliteration

Obliterative bronchiolitis (OB) limits the long‐term success of lung transplantation, while T‐cell effector mechanisms in this process remain incompletely understood. Using the murine heterotopic tracheal transplant model of obliterative airway disease (OAD) to characterize airway allograft rejection, we previously reported an important role for CD8⁺ T cells in OAD. Herein, we studied the role of CD154/CD40 costimulation in the regulation of allospecific CD8⁺ T cells, as airway rejection has been reported to be CD154‐dependent. Airway allografts from CD154^−/− recipients had significantly lower day 28 OAD scores compared to wild‐type (WT) recipients, and adoptive transfer of CD8⁺ T cells from WT recipients, but not CD154^−/− recipients, were capable of airway rejection in fresh CD154^−/− allograft recipients. Intragraft CD8⁺ T cells from CD154^−/− mice showed similar expression of the surface markers CD69, CD62L^low CD44^high and PD‐1, but markedly impaired IFN‐γ and TNF‐α secretion and granzyme B expression versus WT controls. Unexpectedly, intragraft and systemic CD8⁺ T cells from CD154^−/− recipients demonstrated robust in vivo expansion similar to WT recipients, consistent with an uncoupling of proliferation from effector function. Together, these data suggest that a lack of CD154/CD40 costimulation results in ineffective allospecific priming of CD8⁺ T cells required for murine OAD.     

Alloreactive (CD4-Independent) CD8+ T Cells Jeopardize Long-Term Survival of Intrahepatic Islet Allografts

Despite success of early islet allograft engraftment and survival in humans, late islet allograft loss has emerged as an important clinical problem. CD8⁺ T cells that are independent of CD4⁺ T cell help can damage allograft tissues and are resistant to conventional immunosuppressive therapies. Previous work demonstrates that islet allografts do not primarily initiate rejection by the (CD4-independent) CD8-dependent pathway. This study was performed to determine if activation of alloreactive CD4-independent, CD8⁺ T cells, by exogenous stimuli, can precipitate late loss of islet allografts. Recipients were induced to accept intrahepatic islet allografts (islet 'acceptors') by short-term immunotherapy with donor-specific transfusion (DST) and anti-CD154 mAb. Following the establishment of stable long-term islet allograft function for 60–90 days, recipients were challenged with donor-matched hepatocellular allografts, which are known to activate (CD4-independent) CD8⁺ T cells. Allogeneic islets engrafted long-term were vulnerable to damage when challenged locally with donor-matched hepatocytes. Islet allograft loss was due to allo specific immune damage, which was CD8- but not CD4-dependent. Selection of specific immunotherapy to suppress both CD4- and CD8-dependent immune pathways at the time of transplant protects islet allografts from both early and late immune damage.     

CD4+ and CD8+ T cell subset distribution in the blood of small-bowel-grafted rats: modification during graft-versus-host disease

Abstract We studied the modifications of blood T cell distribution following small-bowel allografting in rats under different experimental conditions. Group 1: ACI (RT1^a) rats were used as small-bowel donors for ACI × Wistar (RT1^y) F₁, hybrid rats (WAF₁) in which graft-versus- host disease (GVHD) developed. Group 2: WAF₁ rats were used as small bowel donors to ACI rats which developed rejection. Group 3: WAF₁ rats received small bowel from ACI rats hyperimmunized for 10 days (by grafting them with WAF₁ skin) and GVHD developed. Group 4: Wistar rats received small bowel from ACI rats hyperimmunized for 10 days (by Wistar skin) and bidirectional GVHD and rejection were assured. A second set of the same groups which were continuously administered with cyclosporin (15 mg/kg per day s.c. for 15 consecutive days) was also studied. Recipient peripheral blood lymphocytes, obtained at 7 and 15 days following small-bowel transplantation, were stained with monoclonal antibodies anti-rat CD4 and CD8 and then analyzed in an automated flow cytometer. A significant major reduction of CD4⁺/CD8⁺ T cell ratios was shown in rats that developed simultaneous GVHD and rejection with respect to ungrafted rats.     

CD8+CD28-T细胞在脑疝患者的动态变化与临床意义

【摘要】 目的 探讨脑疝患者外周血CD8+CD28-T细胞的动态变化与临床意义。方法〓收集36例脑疝组(A组)患者外周血,以41例未出现脑疝的重型颅脑损伤患者(B组)及32例健康人(C组)作为对照,采用流式细胞术检测外周血CD8+CD28-T细胞及其胞内转化生长因子β1(TGF-β1)及白介素10(IL-10)百分含量。分别在伤后3 h、6 h及12 h观察A及B组患者外周血CD8+CD28-T细胞、TGF-β1及IL-10变化。结果〓三组CD8+CD28-T细胞、TGF-β1及IL-10总体差异均有显著性(P < 0.05),但B组与C组无统计学差异,而A组上述三者均显著低于另外B及C组(P < 0.05)。B组患者在伤后3 h、6 h及12 h的CD8+CD28-T细胞、TGF-β1及IL-10差异均无统计学意义|A组患者3 h、6 h及12 h的CD8+CD28-T细胞、TGF-β1及IL-10均呈进行性下降,表现为任意两个时间点的差异均有统计学意义(P < 0.05),且均显著低于B组(P < 0.05)。结论〓CD8+CD28-T细胞显著下降是脑疝患者的一个重要细胞免疫学特征,其伤后12h内进行性下降与病情进展密切相关。     

Islet allograft rejection by contact-dependent CD8+ T cells: perforin and FasL play alternate but obligatory roles.

Though CD8(+) T lymphocytes are important cellular mediators of islet allograft rejection, their molecular mechanism of rejection remains unidentified. Surprisingly, while it is generally assumed that CD8(+) T cells require classic cytotoxic mechanisms to kill grafts in vivo, neither perforin nor FasL (CD95L) are required for acute islet allograft rejection. Thus, it is unclear whether such contact-dependent cytotoxic pathways play an essential role in islet rejection. Moreover, both perforin and CD95L have been implicated in playing roles in peripheral tolerance, further obscuring the role of these effector pathways in rejection. Therefore, we determined whether perforin and/or FasL (CD95L) were required by donor MHC-restricted ('direct') CD8(+) T cells to reject islet allografts in vivo. Islet allograft rejection by primed, alloreactive CD8(+) T cells was examined independently of other lymphocyte subpopulations via adoptive transfer studies. Individual disruption of T-cell-derived perforin or allograft Fas expression had limited impact on graft rejection. However, simultaneous disruption of both pathways prevented allograft rejection in most recipients despite the chronic persistence of transferred T cells at the graft site. Thus, while there are clearly multiple cellular pathways of allograft rejection, perforin and FasL comprise alternate and necessary routes of acute CD8(+) T-cell-mediated islet allograft rejection.     

Treatment with recombinant human erythropoietin is associated with rejuvenation of CD8+ T cell compartment in chronic renal failure patients.

BACKGROUND: A growing body of evidence suggests an impact of rHuEpo on the immune system. METHODS: We assessed the impact of recombinant human erythropoietin (rHuEpo) on the immunity of 11 chronic renal failure patients who did not require haemodialysis. Na?ve (Tn), central (Tcm) and effectory memory (Tcm, Tem, TemRA) subsets of CD8+ T cells, memory-CMV-specific CD8+ T cells, titres of anti-CMV antibodies and activity of NK cells were evaluated during the first year of rHuEpo administration. RESULTS: While the number of CD8 T cells did not change, significant change was found in their proportions. Percentage of Tn cells increased at the expense of Tcm cells. Appearing Tn cells were CD28+ increasing the total pool of CD28+ T cells. Together with decreasing number, Tcm cells changed to mainly CD28- Tcm cells. A 'move' towards the na?ve compartment was also confirmed as the level of memory-CMV-specific CD8+ T cells decreased. Humoral immunity analysed as titres of anti-CMV antibodies as well as innate immunity measured as cytotoxicity of NK cells did not change during the follow-up. CONCLUSIONS: We found that the administration of rHuEpo caused rejuvenation of cellular CD8+ T-dependent immunity in our patients.     

Human CD8 responder cells can be directly activated to proliferate and to produce IL-2 following stimulation by allogeneic, but not by xenogeneic, porcine blood mononuclear cells

Abstract: In order to determine the precise nature of human T lymphocytes reactivity against porcine stimulator cells, purified CD4₊ and CD8+ human peripheral T lymphocytes have been tested for their responsiveness against porcine stimulator cells. In a xenogeneic mixed lymphocyte reaction (MLR), CD4+ T cells were capable of proliferating as a result of the recognition of porcine peripheral blood lymphocytes (PBL), whereas CD8+ T cells were unresponsive. A proliferative response of CD8+ T cells could be restored by treatment with human IL-2, but not by IL-lα, IL-lβ, or IL-6. Production of IL-2 was not detected in the xenostimulated CD8+ responder cells, nor could IL-2 production be restored by the addition of IL-lα, IL-1β, or IL-6. The presence of human CD4₊ responder cells was crucial both for a xenoproliferative response and for IL-2 synthesis. However, when the expression of the IL-2 receptor (CD25) on the CD8₊ T cells was analyzed, no difference was detected between xenostimulated and allostimulated CD8₊ T cells. When the development of cytotoxic T cells in xenogeneic and allogeneic MLRs was compared, the cytotoxic activity exhibited by purified CD8+ T cells in xenogeneic MLR was significantly lower than that in the allogeneic combination. In the xenogeneic combination, exogenous IL-2 reconstituted the cytotoxicity by purified CD8₊ T cells; however, IL-lα, IL-lβ, or IL-6 did not.
Our results show that purified human CD4₊ T cells respond directly against pig PBMCs, whereas purified CD8₊ T cells do not. Furthermore, responsiveness in CD8₊ T cells is completely restored by the addition of human IL-2.     

EBV-Specific CD8+ T Cell Reactivation in Transplant Patients Results in Expansion of CD8+ Type-1 Regulatory T Cells

Posttransplantation lymphoproliferative disorders (PTLD) are life-threatening complications of solid organ transplantation, triggered by EBV infection in chronically immunosuppressed (IS) patients. Our goal is to establish DC-based protocols for adoptive immunotherapy of refractory PTLD, while understanding how the immunosuppressive drug environment may subvert DC-EBV-specific T cell interactions. Type-1 CD8(+) T cells are critical for efficient immune surveillance and control of EBV infection, whereas type-2 or Treg/type-3 responses may provide an environment conductive to disease progression. We have recently reported that chronic IS inhibits DC function in transplant patients. Here, we have analyzed the comparative ability of mature, type-1 polarized DCs (i.e. DC1) generated from quiescent transplant patients or healthy controls, to boost type-1 EBV-specific CD8(+) T cells in vitro. Our results show that unlike healthy controls, where DC1 loaded with MHC class I EBV peptides preferentially reactivate specific type-1 CD8(+) T cells, DC1 generated from transplant patients reactivate EBV-specific CD8(+) T cells that produce both IFN-gamma and IL-10, up-regulate FOXP3 mRNA, and suppress noncognate CD4(+) T-cell proliferation via cell-cell contact. These data support a novel regulatory pathway for anti-EBV T-cell-mediated responses in IS transplant patients, with implications for the design of adoptive immunotherapies in this setting.