Naïve subset develops the most important alloreactive response among human CD4+ T lymphocytes in Human Leukocyte Antigen‐identical related setting

In longitudinal clinical studies, receiving a high percentage of allogeneic donor‐derived CD4⁺CCR7⁺ T cells, which include naïve and central memory subsets have been correlated with increased incidence and severity of acute GVHD. Whether naïve and central memory CD4⁺ T‐cell subsets contribute more or equally to alloimmune responses are still unclear in human. The aim of this study was to investigate in vitro the alloreactive response of purified naïve, central memory, and effector memory CD4⁺ T‐cell subsets in HLA identical setting. By coculturing monocyte‐derived dendritic cells and purified CD4⁺ T‐cell subsets, from healthy HLA‐identical male and female sibling pairs, we found that naïve CD4⁺CCR7⁺CD45RA⁺ T cells developed the highest proliferative response upon stimulation by minor histocompatibility antigens and were progressively driven to produce high levels of interferon‐γ, tumor necrosis factor, and interleukin‐6. Comparatively, the central memory CD4⁺CCR7⁺CD45RA^neg subset proliferated to a lower extent and produced very low amounts of pro‐inflammatory cytokines while the CCR7^neg effector memory CD4⁺ subset was unresponsive. This study demonstrates the superior capacity of naïve CD4⁺ T cells to mount a primary alloreactive response as compared to central memory T cells. Their proliferative response associated with a pro‐inflammatory differentiation makes them potentially acute GVHD inducers. These in vitro results in line with what we have observed in clinical studies and may also lend support to approaches of partial selective T‐cell depletion for GVHD prevention.     

Relationship between cytomegalovirus (CMV) reactivation,CMV‐driven immunity,overall immune recovery and graft‐versus‐leukaemia effect in children

The interplay between immune recovery, cytomegalovirus (CMV)‐reactivation, CMV‐driven immunity and graft‐versus‐leukaemia effect (GVL) was analysed in 108 children (median age: 8 years) who underwent haematopoietic‐stem cell transplantation (HSCT) for acute leukaemia. Follow‐up was 2 years unless death or relapse occurred. CMV‐polymerase chain reaction (PCR) was programmed weekly until month +3 post‐HSCT. Immunomonitoring consisted of sequential lymphocyte subset enumerations and analyses of T‐cell proliferative and γ‐interferon responses to CMV and to adenovirus. In the 108 recipients, the 2‐year relapse rate (RR) was 25% (median time to onset 4·5 months; range: 24 d–17 months). CMV reactivation occurrence was 31% (median time to onset 26 d). Donor/recipient CMV serostatus did not influence RR. Among the 89 recipients disease‐free after day +120, i) early CMV‐reactivation before day +30 was more frequent (P = 0·01) in the relapse recipient group opposed to the non‐relapse group. ii) CD8⁺/CD28^? and CD4⁺CD45RA^? T‐cell expansions induced by CMV did not influence RR, iii) Recovery of anti‐CMV and also anti‐adenovirus immunity and of naïve CD4⁺ T‐cells was faster in the non‐relapse group (P = 0·008; 0·009 and 0·002 respectively). In contrast to adult acute myeloid leukaemia, CMV reactivation was associated with increased RR in this paediatric series. Accelerated overall immune recovery rather than CMV‐driven immunity had a favourable impact on RR.     

Prevention of red cell alloimmunization by CD25 regulatory T cells in mouse models

Transfusion therapy is currently an effective therapeutic intervention in a number of diseases, including sickle cell disease. However, its use is complicated by a high incidence of red blood cell (RBC) alloimmunization in the transfusion recipients. The identification of T regulatory cells (Tregs) among the CD4⁺ CD25⁺ T cell subset as key regulators of peripheral tolerance in mice as well as humans has opened an exciting era in the prevention and treatment of autoimmune disease and for improving organ transplantation. However, their potential in inducing transfusion tolerance remains to be explored. We used red cells from mice transgenic for human glycophorin A blood group antigen as donor cells and transfused wild‐type mice to induce alloantibodies, as an experimental system to study RBC alloimmunization. We found that depletion with anti‐CD25 enhanced the alloantibody production, indicating that CD25 Tregs play an important role in regulation of alloantibody responses. More importantly, adoptive transfer of purified population of CD4⁺CD25⁺ but not CD4⁺CD25^? cells from naïve mice prevented the induction of IgG and IgM alloantibody production in transfusion recipients, with a concomitant reduction in activated splenic B cells and macrophages. Similarly, adoptive transfer of purified populations of CD4⁺CD25⁺ cells from naïve mice into naïve syngeneic recipients inhibited the anti‐Ig response to rat RBCs in the recipients but transfer of control CD4⁺CD25^? cells did not. Altogether, our results demonstrate that Tregs participate in the control of transfusion‐associated RBC alloantibody responses, opening up the possibility that Treg immunotherapy may be exploited for suppressing transfusion immunization events. Am. J. Hematol., 2007. © 2007 Wiley‐Liss, Inc.     

Lymphopenia in patients with chronic idiopathic neutropenia is associated with decreased number of T-lymphocytes containing T-cell receptor excision circles

Objectives: Chronic idiopathic neutropenia (CIN) is a disorder of granulopoiesis characterized by the presence of activated T‐lymphocytes that induce/sustain apoptosis of bone marrow (BM) granulocytic progenitors. T‐cell lymphopenia is commonly found in CIN. The aim of the study is to probe the mechanisms underlying T‐cell lymphopenia in CIN. Methods: We investigated parameters of T‐cell homeostasis namely the proliferation/apoptotic rate of naïve and memory T cells, the T‐cell senescence by telomere measurement, the recent thymic T‐cell production through quantification of T‐cell receptor rearrangement excision circles (TRECs), and the production of interleukin (IL)‐7. Results: Patients with CIN (n = 44) displayed lower proportion of naïve CD45RA⁺ cells within the CD4⁺ and CD8⁺ cells compared with controls (n = 15). The proportion of apoptotic cells within the CD8⁺ fraction was higher in patients compared with controls and was correlated with the percentage of Ki‐67⁺ cells, indicating an activation‐induced accelerated CD8⁺ cell death. The TREC content of CD4⁺ and CD8⁺ cells was lower in patients compared with controls and was correlated with the proportion of CD45RA⁺ CD4⁺ and CD8⁺ cells and with the levels of serum and BM IL‐7, which were significantly decreased in the patients. The mean relative telomere length of CD4⁺ and CD8⁺ cells was significantly lower in patients with CIN compared with age‐matched controls. Conclusions: The aberrant T‐cell expansions associated with the pathogenesis of CIN result in increased proliferation/apoptosis and possibly exhaustion of peripheral blood T cells which, in association with the inadequate compensatory thymic export of new TREC expressing T cells partially because of IL‐7 deficiency, may contribute to lymphopenia in CIN.     

Age-matched lymphocyte subpopulation reference values in childhood and adolescence: application of exponential regression analysis

Background: Normal values of lymphocyte subpopulations for healthy children and adults have been published in defined age groups exclusively, which results in difficult data interpretation for patients close to the limit of contiguous age group ranges. In addition, normal values for a number of lymphocyte subpopulations have not been established to date. Objective: The aim of this study was to develop a model which provides continuous age‐dependent reference values. This model was applied for lymphocyte subpopulations such as naïve and memory T cells as well as their activation profile with diagnostic relevance in children and adults. Study design: A total of 100 blood samples, obtained from 80 healthy children and 20 adults were analysed by means of four colour‐flow cytometry. Continuous age‐dependent reference values were computed based on the residual values in an exponential regression model. Results: We calculated a continuous age‐related regression model for both, absolute cell counts and percentages of CD3⁺CD4⁺ T helper (T_H) cells, CD3⁺CD8⁺ cytotoxic T cells, CD56⁺CD3^? natural killer (NK) cells, CD56⁺CD3⁺ T cells, CD3⁺CD4⁺CD45RA⁺ naïve T_H cells, CD3⁺CD4⁺CD45RO⁺ memory T_H cells, CD3⁺CD8⁺CD45RA⁺CD28⁺ naïve cytotoxic T cells, CD3⁺CD8⁺CD45RO⁺ memory cytotoxic T cells, CD3⁺CD8⁺CD69⁺ early activated cytotoxic T cells and CD3⁺CD8⁺HLA‐DR⁺ late activated cytotoxic T cells, respectively, to obtain reference values. Conclusion: Based on an exponential regression model, the obtained reference values reflect the continuous maturation of lymphocyte subsets during childhood.     

Lymphocyte subset reconstitution after unrelated cord blood or bone marrow transplantation in children

We report the post‐transplant lymphocyte subset recovery of 226 children treated with Unrelated Cord Blood transplant (UCBT) (n = 112) or Unrelated Bone Marrow Transplant (UBMT) (n = 114) for malignant or non‐malignant diseases. Absolute numbers of natural killer (NK), B and T cells were monitored by flow cytometry up to 5 years post‐transplant. Immunological endpoints were: time to achieve a CD3⁺ cell count >0·5 and 1·5 × 10⁹/l, CD4⁺ > 0·2 and 0·5 × 10⁹/l, CD8⁺ > 0·25 × 10⁹/l, CD19⁺ > 0·2 × 10⁹/l, NK > 0·1 × 10⁹/l. These endpoints were analysed through the use of cumulative incidence curves in the context of competing risks. CD8⁺ T cell recovery was delayed after UCBT with a median time to reach CD8⁺ T cells > 0·25 × 10⁹/l of 7·7 months whereas it was 2·8 months in UBMT (P < 0·001). B cell recovery was better in UCBT, with a median time to reach CD19⁺ cells > 0·2 × 10⁹/l of 3·2 months in UCBT and 6·4 months in UBMT (P = 0·03). Median time for CD4⁺ T cell and NK cell recovery was similar in UCBT and UBMT. CD4⁺ T cells recovery was negatively correlated to age (better reconstitution in younger patients, P = 0·002). CD8⁺ T cells recovery was shorter in recipients with a positive cytomegalovirus serology (P = 0·001).     

Cytokine profile of Plasmodium falciparum-specific T cells in non-immune malaria patients

CD3⁺ T cells are important sources of both pro‐ and anti‐inflammatory cytokines during Plasmodium falciparum malaria. We studied the frequency of interleukin‐2 (IL‐2), gamma interferon (IFN‐γ), tumour necrosis factor‐alpha (TNF‐α) and IL‐10 expressing CD3⁺ cells in 10 non‐immune malaria patients with uncomplicated malaria and in one patient with cerebral malaria after P. falciparum‐specific and non‐specific mitogenic stimulation. Analysis by fluorescence‐activated cell sorting was performed after drug‐induced clearance of parasites to allow previously sequestered T cells to be detected in peripheral blood. CD3⁺ cells of patients responded to P. falciparum infected erythrocytes with significant increases in the percentage of IL‐2, IFN‐γ, and TNF‐α, but also IL‐10, positive cells. CD3⁺ cells from malaria‐naïve donors were also responsive to specific stimulation albeit to a much lesser extent. Mitogenic stimulation of PBMC revealed no significant differences between cells of patients and controls. CD3⁺ cells of the patient with cerebral malaria were hyporesponsive both to the infecting parasite isolate as well as to our laboratory‐adapted P. falciparum isolate, whereas two patients with uncomplicated disease were more responsive to their infecting parasites than to the laboratory‐adapted isolate. The results indicate that the increased responsiveness of in vivo primed compared to malaria‐naïve CD3⁺ cells is Plasmodium‐specific and biased towards production of IFN‐γ and TNF‐α.     

Omission of in vivo T-cell depletion promotes rapid expansion of naïve CD4+ cord blood lymphocytes and restores adaptive immunity within 2 months after unrelated cord blood transplant

Umbilical cord blood transplant (UCBT) is associated with impaired early immune reconstitution. This might be explained by a lower T‐cell dose infused, the naivety of cord blood T‐cells and the use of in vivo T‐cell depletion. We studied the pattern of early immune reconstitution and the clinical outcome of children undergoing unrelated UCBT when in vivo T‐cell depletion was omitted. Thirty children affected by malignancies (46%) or immunodeficiencies (54%) underwent an unrelated UCBT. Prospective assessment of immune reconstitution and clinical outcome was performed. We observed an unprecedented CD4⁺ T‐cell reconstitution, with a median cell count at 30 and 60 d post UCBT of 0·3 × 10⁹/l and 0·56 × 10⁹/l, respectively. Early T‐cell expansion was thymic‐independent, with a rapid shift from naïve to central memory phenotype and early regulatory T‐cell recovery. Viral infections were frequent (63%) but resolved rapidly in most cases and virus‐specific T‐lymphocytes were detected within 2 months post‐UCBT. Acute graft‐versus‐host disease (GvHD) was frequent (grade II = 34%, grade III–IV = 16%) but steroid responsive, and the incidence of chronic GvHD was low (14%). The omission of in vivo T‐cell depletion promotes a unique thymic‐independent CD4⁺ T‐cell reconstitution after unrelated UCBT in children. We postulate that this relates to the specific immunological and ontological qualities of fetal‐derived lymphocytes.     

Allogeneic transplantation using CD34+ selected peripheral blood progenitor cells combined with non‐mobilized donor T cells for refractory severe aplastic anaemia

Allogeneic haematopoietic stem cell transplantation is curative for severe aplastic anaemia (SAA ) unresponsive to immunosuppressive therapy. To reduce chronic graft‐versus‐host disease (GVHD ), which occurs more frequently after peripheral blood stem cell (PBSC ) transplantation compared to bone‐marrow transplantation (BMT ), and to prevent graft rejection, we developed a novel partial T‐cell depleted transplant that infuses high numbers of granulocyte colony‐stimulating factor‐mobilized CD 34⁺ selected PBSC s combined with a BMT ‐equivalent dose of non‐mobilized donor T‐cells. Fifteen patients with refractory SAA received cyclophosphamide, anti‐thymocyte globulin and fludarabine conditioning, and were transplanted with a median 8 × 10⁶ CD 34⁺ cells/kg and 2 × 10⁷ non‐mobilized CD 3⁺ T‐cells/kg from human leucocyte antigen‐matched sibling donors. All achieved sustained engraftment with only two developing acute and two developing chronic GVHD . With a 3·5‐year median follow‐up, 86% of patients survived and were transfusion‐independent. When compared to a retrospective cohort of 56 bone‐marrow failure patients that received the identical transplant preparative regimen and GVHD prophylaxis with the exception that the allograft contained unmanipulated PBSC s, partial T‐cell depleted transplant recipients had delayed donor T‐cell chimerism and relative reduction of 75% in the incidence of acute grade II ‐IV GVHD (13% vs. 52%; P  =  0·010) and of 82% in chronic GVHD (13% vs. 72%; P  =  0·0004). In multivariate analysis, partial T‐cell depleted transplants remained significantly associated with a reduced risk of GVHD . In conclusion, for patients with refractory SAA , this novel transplant strategy achieves excellent engraftment and survival when compared to unmanipulated PBSC transplants and dramatically reduces the incidence of both acute and chronic GVHD .     

Moderate and intense exercise lifestyles attenuate the effects of aging on telomere length and the survival and composition of T cell subpopulations

Studies indicate that exercise might delay human biological aging, but the effects of long-term exercise on T cell function are not well known. We tested the hypothesis that moderate or intense exercise lifestyle may attenuate the effects of aging on the telomere length and the survival and composition of T cell subpopulations. Elderly (65–85 years) with intense training lifestyle (IT, n?=?15), moderate training lifestyle (MT, n?=?16), and who never trained (NT, n?=?15) were studied. Although the three groups presented the age-associated contraction of the TCD4⁺/TCD8⁺ naïve compartments and expansion of the memory compartments, both training modalities were associated with lower proportion of terminally differentiated (CD45RA⁺CCR7^neg) TCD4⁺ and TCD8⁺ cells, although among the latter cells, the reduction reached statistical significance only with IT. MT was associated with higher proportion of central memory TCD4⁺ cells, while IT was associated with higher proportion of effector memory TCD8⁺ cells. However, both training lifestyles were unable to modify the proportion of senescent (CD28^neg) TCD8⁺ cells. Telomeres were longer in T cells in both training groups; with IT, telomere length increased mainly in TCD8⁺ cells, whereas with MT, a modest increase in telomere length was observed in both TCD8⁺ and TCD4⁺ cells. Reduced commitment to apoptosis of resting T cells, as assessed by caspase-3 and Bcl-2 expression, was seen predominantly with IT. Measurement of pro-inflammatory cytokines in serum and peripheral blood mononuclear cell (PBMC)’s supernatants did not show chronic low-grade inflammation in any of the groups. In conclusion, MT and IT lifestyles attenuated some of the effects of aging on the immune system.     

Early development of human hematopoietic and acquired immune systems in new born NOD/Scid/Jak3<Superscript>null</Superscript> mice intrahepatic engrafted with cord blood-derived CD34<Superscript>+</Superscript> cells

An animal model in which the human immune system can be reconstituted is necessary to study acquired immunity in vivo. We report here a novel model, the NOD/SCID/JAK3^null mouse, for the human immune system’s development. Newborn mice transplanted with human cord blood CD34⁺ cells intrahepatically, developed human T and B cells, and myeloid and plasmacytoid dendritic cells. The T and B cells had a naïve to memory phenotype, and included plasma cells. The human acquired immune system can be reconstituted from CD34⁺ cells in NOD/SCID/JAK3^null mice. This model is a powerful tool for the study of human immunity.     

Mucosal T‐cell responses to HIV: responding at the front lines

Mucosal surfaces of the body serve as the major portal of entry for human immunodeficiency virus (HIV). These tissues also house a majority of the body’s lymphocytes, including the CD4⁺ T cells that are the major cellular target for HIV infection. Mucosal surfaces are defended by innate and adaptive immune mechanisms, including secreted antibodies and CD8⁺ cytotoxic T cells (CTL). CTL in mucosal lymphoid tissues may serve to limit viral replication, decreasing the host’s viral burden as well as reducing the likelihood of sexual transmission to a naïve host. This review summarizes recent literature on HIV‐specific T‐cell responses in mucosal tissues, with an emphasis on the gastrointestinal tract.     

In vivo imaging studies of the effect of recipient conditioning,donor cell phenotype and antigen disparity on homing of haematopoietic cells to the bone marrow

Summary. Homing of transplanted bone marrow cells (BMC) to the host bone marrow (BM) is the first step of engraftment towards durable multilineage haematopoietic reconstitution. We used an in vivo assay to track PKH‐labelled cells in the BM of mice after transplantation, using fluorescence microscopy through an optical window placed over the distal femoral epiphysis. Within hours after intravenous injection, the cells moved in and out the femur, and were mobile within the marrow space. One hour after injection of whole BMC into non‐conditioned syngeneic and allogeneic recipients, the homing efficiencies (HE) were 1·23 ± 0·14% and 0·12 ± 0·02% respectively (P < 0·001). Irrespective of antigen disparity, the number of PKH‐labelled cells in the femur decreased by 30% and 50% after 1 and 3 d respectively (P < 0·001). Similar HE of naïve and irradiated cells suggested that the majority of cells (> 80%) were quiescent in the BM during the first 3 d. HE were twofold higher in busulphan‐myeloablated recipients (P < 0·001 vs non‐conditioned), and allogeneic transplantation resulted in 84 ± 9% donor chimaerism at 4 weeks. The HE of lin^– cells was 16‐fold higher than that of lin⁺ cells (P < 0·001), and the subset of lin^– SCA‐1⁺ cells was 4·6‐fold higher in the BM‐homed cell population (P < 0·001 vs lin^– cells). Approximately 1500 of the BM‐homed cells rescued 62–71% secondary syngeneic and allogeneic myeloablated recipients. Strikingly, the HE could be predicted during the first 3 d after transplantation by correcting the measurements performed in vivo for the enrichment of progenitors in donor inoculum, donor‐recipient antigen disparity and myeloablative conditioning.     

Cell-contact-dependent activation of CD4+ T cells by adhesion molecules on synovial fibroblasts

Objective: To determine how cell–cell contact with synovial fibroblasts (SF) influence on the proliferation and cytokine production of CD4^+?T cells.

Methods: Naïve CD4^+?T cells were cultured with SF from rheumatoid arthritis patients, stimulated by anti-CD3/28 antibody, and CD4^+?T cell proliferation and IFN-γ/IL-17 production were analyzed. To study the role of adhesion molecules, cell contact was blocked by transwell plate or anti-intracellular adhesion molecule-1 (ICAM-1)/vascular cell adhesion molecule-1(VCAM-1) antibody. To study the direct role of adhesion molecules for CD4^+?T cells, CD161^+?or CD161^- naïve CD4^+?T cells were stimulated on plastic plates coated by recombinant ICAM-1 or VCAM-1, and the source of IFN-γ/IL-17 were analyzed.

Results: SF enhanced naïve CD4^+?T cell proliferation and IFN-γ/IL-17 production in cell-contact and in part ICAM-1-/VCAM-1-dependent manner. Plate-coated ICAM-1 and VCAM-1 enhanced naïve CD4^+?T cell proliferation and IFN-γ production, while VCAM-1 efficiently promoting IL-17 production. CD161^+?naïve T cells upregulating LFA-1 and VLA-4 were the major source of IFN-γ/IL-17 upon interaction with ICAM-1/VCAM-1.

Conclusion: CD4^+?T cells rapidly expand and secrete IFN-γ/IL-17 upon cell-contact with SF via adhesion molecules. Interfering with ICAM-1-/VCAM-1 may be beneficial for inhibiting RA synovitis.     

Diminution of Circulating CD4<Superscript>+</Superscript>CD25<Superscript>high</Superscript> T Cells in Na?ve Crohn’s Disease

Crohn’s disease is considered to be caused either by an excess of T-cell effector functions and/or by a defective regulatory T-cell compartment. The aim of this study was to assess in Crohn’s disease the frequency of circulating CD4⁺CD25^high T cells that possess regulatory T-cell functions and CD4⁺CD25^low T cells that contain activated T cells. Flow cytometry of peripheral blood was used to assess CD4⁺CD25^high and CD4⁺CD25^low T-cell frequencies in a cohort of 66 patients with Crohn’s disease in comparison to 19 patients with ulcerative colitis and 31 healthy individuals enrolled as controls. The CD4⁺CD25^high T-cell frequency was significantly lowered in naïve Crohn’s disease (P = 0.013) and in ulcerative colitis (P = 0.001). CD4⁺CD25^low T-cell frequency was increased in Crohn’s disease (P = 0.0001) and in ulcerative colitis (P = 0.0002). Both CD4⁺CD25^high and CD4⁺CD25^low T-cell frequencies are altered in naïve Crohn’s disease resulting in an imbalance between both populations and a relative contraction of the CD4⁺CD25^high T-cell population.     

Long-lasting changes in the T-cell receptor V beta repertoires of CD4 memory T-cell populations in the peripheral blood of radiation-exposed people

Summary. To study the long‐term effects of radiation‐induced T‐cell depletion on the T‐cell receptor (TCR) Vβ repertoires of human peripheral CD4 T‐cell populations, we measured the percentages of CD4 T cells representing each of the full range of possible TCR Vβ families in a cohort of atomic bomb survivors. We then estimated the extent to which the expression levels for individual TCR Vβ families differed from the average expression level for that particular TCR Vβ family across the entire cohort. We found no evidence of a systematic change in the TCR Vβ repertoires of the naïve CD4 T‐cell populations, but memory CD4 T‐cell TCR Vβ family expression levels diverged significantly from the population average for counterpart families, especially in individuals who had been exposed to higher doses and were at least 20 years of age at the time of the bombing. Comparisons of the TCR Vβ family expression profiles in the naïve and memory CD4 T‐cell pools of the same group of adult survivors revealed that differences in the TCR Vβ repertoires of these two types of CD4 T‐cell pool were larger in more heavily exposed survivors than in unexposed controls. These findings suggest that the memory CD4 T‐cell pools of individuals who received significant radiation doses in adulthood may well have become (and could still be) dependent upon a much less diverse complement of TCR Vβ families than would otherwise have been the case.     

Abnormal expansion of naïve B lymphocytes after unrelated cord blood transplantation – a case report

A 33‐year‐old woman underwent unrelated cord blood transplantation (U‐CBT) for myelodysplastic syndrome (MDS)‐related secondary AML. She showed impressive increases in the number of CD19⁺ B cells in bone marrow and CD19⁺27^?IgD⁺ B cells in peripheral blood from about 1 month to 3 months after U‐CBT. The serum level of IL‐6 temporarily increased after transplantation, and this increase seemed to be correlated with the expansion of CD19⁺ B cells. Although, compared with BMT, little is known about the kinetics of hematological and immunological reconstitution in U‐CBT, there was initial B‐cell recovery after CBT as some described. This B cell recovery may be associated with a high number of B‐cell precursors present in cord blood (CB). The phenomenon of naïve B lymphocyte expansion that we found might be associated with a high number of B‐cell precursors present in CB.     

Paroxysmal nocturnal haemoglobinuria phenotype cells and leucocyte subset telomere length in childhood acquired aplastic anaemia

The significance of paroxysmal nocturnal haemoglobinuria (PNH^pos) cells and leucocyte subset telomere lengths in paediatric aplastic anaemia (AA) is unknown. Among 22 children receiving immunosuppressive therapy (IST) for AA, 73% (16/22) were PNH^pos, of whom 94% achieved at least a partial response (PR) to IST; 11/16 (69%) achieved complete response (CR). Only 2/6 (33%) PNH^neg patients achieved PR. PNH^pos patients were less likely to fail IST compared to PNH^neg patients (odds ratio 0·033; 95% confidence interval 0·002–0·468; P = 0·012). Children with AA had short granulocyte (P = 7·8 × 10^?9), natural killer cell (P = 6·0 × 10^?4), naïve T lymphocyte (P = 0·002) and B lymphocyte (P = 0·005) telomeres compared to age‐matched normative data.     

Mechanistic insights into the impairment of memory B cells and antibody production in the elderly

It is well established that immunologic memory generated early in life can be maintained into old age and mediate robust anamnestic antibody responses. Little is known, however, about the initiation of memory B cells in the elderly. We have conducted a prospective analysis of the quantities and functionalities of antigen-specific B cell responses and its association with the functional helper CD4⁺T cell responses. The ability of naïve B cells from old (60–80 years) and young (20–31 years) humans to establish functional memory was examined following primary and booster vaccination with an inactivated-virus vaccine against tick-borne encephalitis. Our data show that the number of antigen-specific memory B cells generated during primary vaccination was ～3-fold lower in old than in young individuals. The maintenance and booster responsiveness of these memory B cells were not compromised, as evidenced by similar increases in specific memory B cell frequencies upon revaccination in old and young adults. In contrast, the Ab response mediated per memory B cell after revaccination was dramatically diminished in the elderly. Also, antigen-specific IL-2-positive CD4⁺T cell responses were strongly reduced in the elderly and displayed an excellent correlation with Ab titres. The data suggest that the dramatically lower antibody response in the elderly could only partially be accounted for by the reduced B cell numbers and was strongly correlated with profound functional defects in CD4 help.     

A novel immunogenic CS1-specific peptide inducing antigen-specific cytotoxic T lymphocytes targeting multiple myeloma

The CS1 antigen provides a unique target for the development of an immunotherapeutic strategy to treat patients with multiple myeloma (MM). This study aimed to identify HLA‐A2⁺ immunogenic peptides from the CS1 antigen, which induce peptide‐specific cytotoxic T lymphocytes (CTL) against HLA‐A2⁺ MM cells. We identified a novel immunogenic HLA‐A2‐specific CS1_239‐247 (SLFVLGLFL) peptide, which induced CS1‐specific CTL (CS1‐CTL) to MM cells. The CS1‐CTL showed a distinct phenotype, with an increased percentage of effector memory and activated CTL and a decreased percentage of naïve CTL. CS1_239‐247 peptide‐specific CD8⁺ T cells were detected by DimerX analyses and demonstrated functional activities specific to the peptide. The CTL displayed HLA‐A2‐restricted and antigen‐specific cytotoxicity, proliferation, degranulation and γ‐interferon (IFN‐γ) production against both primary MM cells and MM cell lines. In addition, the effector memory cells subset (CD45RO⁺CCR7^?/CD3⁺CD8⁺) within CS1‐CTL showed a higher level of CD107a degranulation and IFN‐γ production as compared to effector cells (CD45RO^?CCR7^?/CD3⁺CD8⁺) against HLA‐A2⁺ primary MM cells or MM cell lines. In conclusion, this study introduced a novel immunogenic HLA‐A2‐specific CS1_239‐247 peptide capable of inducing antigen‐specific CTL against MM cells that will provide a framework for its application as a novel MM immunotherapy.