Ontogeny of cytokine responses to PHA from birth to adulthood.

BACKGROUND: Altered production of cytokines is believed to contribute to early childhood susceptibility to infection. The aim of this study was to get further insight into the developmental patterns of cytokine responses from birth to adulthood. METHODS: The expression levels of 13 cytokines were compared in the supernatants of phytohemaggluttinin (PHA)-stimulated whole blood from healthy neonates (cord blood, n = 8), infants ( < 1-year-old, n = 20), and school-aged children (3-15 y; n = 20). Five adults were used as reference. RESULTS: While Th1, Th2, and Th17 cytokine levels increased progressively from birth to childhood (Mann-Whitney, p < 0.003), high IL-10 secretion at birth dropped to low adult levels in infants (p < 0.004) such that a negative correlation between IL-10 and Th1, Th2, and Th17 cytokine levels at birth (Spearman's correlation, r < -0.70, p < 0.01) converted to a positive correlation in infants (r > 0.60, p < 0.001). Finally, high IL-2, IL-7, and Granulocyte-Colony Stimulating factor (G-CSF) cytokine levels at birth decreased steadily over the first year of life (Mann-Whitney, p ≤ 0.001). CONCLUSION: The most noticeable result of the study is the rapid shift from enhanced IL-10 secretion capacity at birth toward balanced IL-10/Th1/Th2/Th17 cytokine levels early in life. This change appears an essential precondition to fight pathogens and at the same time to avoid overwhelming inflammatory reactions.

HLA-DRB3/4/5 mismatches are associated with increased risk of acute GVHD in 10/10 matched unrelated donor hematopoietic cell transplantation.

Matching for HLA-A, -B, -C, and -DRB1 loci (8/8 match) is currently the gold standard for unrelated donor hematopoietic cell transplantation (HCT). In Europe, patients are also matched at the HLA-DQB1 loci (10/10 match). However, there is increasing evidence that matching at HLA-DRB3/4/5 loci may help to lower transplant-related morbidity and mortality. We therefore investigated the impact of HLA-DRB3/4/5 mismatches on outcomes in 1975 patients who received a first 10/10 matched unrelated donor (MUD) HCT in France from 2000 to 2012 for a hematological malignancy. High-resolution typing was performed at HLA-A, -B, -C, -DRB1, -DQB1, -DPB1, and -DRB3/4/5 loci for all donor/recipient pairs. Compared with DRB3/4/5-matched pairs, patients who received a MUD HCT from a DRB3/4/5 mismatched donor had a significantly increased risk of grade II-IV acute graft-versus-host disease (aGVHD) (Adjusted Hazard Ratio (HR) 1.43 (1.07 to 1.90)) associated with lower graft-versus-host disease-free and relapse-free survival (GRFS) (Adjusted HR 1.20 (1.02 to 1.42)). Conversely, we observed no differences in terms of chronic GVHD, nonrelapse mortality, relapse and overall survival. However, we believe that patients stand to benefit from DRB3/4/5 loci being considered for unrelated donor selection to improve GRFS and then quality of life after unrelated HCT.

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.

Impact of donor-specific anti-HLA antibodies on graft failure and survival after reduced intensity conditioning-unrelated cord blood transplantation: a Eurocord, Société Francophone d'Histocompatibilité et d'Immunogénétique (SFHI) and Société Française de Greffe de Moelle et de Thérapie Cellulaire (SFGM-TC) analysis.

Graft failure is a major complication after unrelated cord blood transplantation. Presence of HLA-antibodies before cord blood transplantation may impact graft failure. To analyze the effect of anti-HLA antibodies on unrelated cord blood transplantation outcomes, we analyzed 294 unrelated cord blood transplant recipients after reduced intensity conditioning regimen. The majority of the patients (82%) were transplanted for malignancies, 60% with double-unrelated cord blood transplant, 63% were HLA mismatched. Retrospectively, pre-unrelated cord blood transplant serum was tested for HLA-Ab using Luminex™ platform. Results were interpreted as mean fluorescence intensity (MFI) against donor-specific mismatch. Among 62 recipients (23%) who had anti-HLA antibodies before unrelated cord blood transplant, 14 patients had donor specific anti-HLA antibodies (DSA) (7 were donor-specific anti-HLA antibodies for single unrelated cord blood transplant and 7 for double unrelated cord blood transplant). Donor specific anti-HLA antibodies threshold ranged from 1620-17629 of mean fluorescence intensity (MFI). Cumulative incidence of Day-60 neutrophil engraftment was 76%: 44% for recipients with donor specific anti-HLA antibodies and 81% in those without donor specific anti-HLA antibodies (P=0.006). The cumulative incidence of 1-year transplant related mortality was 46% in patients with donor specific anti-HLA antibodies and 32% in those without antibodies (P=0.06). The presence of donor specific anti-HLA antibodies was associated with a trend for decreased survival rate (42% vs. 29%; P=0.07). Donor specific anti-HLA antibody in recipients of unrelated cord blood transplant is associated with graft failure and decreased survival. Patient's screening for donor specific anti-HLA antibodies before unrelated cord blood transplantation is recommended before choosing an HLA mismatched cord blood unit. Whenever possible it is important to avoid selecting a unit for which the patient has donor specific anti-HLA antibodies.

TNF-α/IL-2 ratio discriminates latent from active tuberculosis in immunocompetent children: a pilot study.

BACKGROUND: Distinguishing latent tuberculosis (LTB) from tuberculosis (TB) disease may be challenging in children. Here, we analyzed cytokine profiles that can distinguish the two infection stages in a nonendemic country (France). METHODS: Immunocompetent children with LTB (n = 6) or TB disease (n = 8) (median age: 6.2 and 5.7 years, respectively) were analyzed. Four young uninfected children were included as controls. A Luminex assay evaluated cytokine responses to Mycobacterium tuberculosis antigens. RESULTS: Poor interleukin-4 (IL-4) and IL-10 responses precluded analysis of these cytokines. Interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), IL-2, and T-helper type 1 (Th1) cytokines and IL-5, IL-13, T-helper type 2 (Th2) cytokines were simultaneously induced by antigens in 14/14 infected but 0/4 uninfected children. Th1 cytokine levels were similar in LTB and TB disease: IFN-γ: 12,254 and 10,495 pg/ml; IL-2: 2,097 and 1,869 pg/ml; and TNF-α: 1,020 and 2,875 pg/ml, respectively. Th2 cytokine levels were similar and even higher in LTB than in TB disease: IL-5: 23 and 10 pg/ml; IL-13: 284 and 109 pg/ml, respectively. Positive correlation of cytokine levels, whether Th1 or Th2, was observed. Higher (P = 0.008) TNF-α/IL-2 ratios distinguished 6/8 active TB disease cases from 6/6 LTB cases. CONCLUSION: TNF-α/IL-2 ratio may discriminate TB disease from LTB in immunocompetent children. Larger studies in TB endemic settings must verify these results.

Quantitative and qualitative CD4 T cell immune responses related to adenovirus DNAemia in hematopoietic stem cell transplantation.

The nature of adenovirus (AdV)-specific T cells that could best predict the capacity of immunocompromised host to fight AdV is unclear. To this aim, 47 pediatric patients were enrolled for at least 3 months either at allogeneic bone marrow transplantation (BMT) (23 genoidentical, 18 unrelated of which 9 were 10/10 and 9 were 9/10 HLA-matched) or at unrelated cord blood transplantation (n = 6). Enumeration of AdV-specific CD4 T cells secreting cytokines (flow cytometry) and proliferative responses to AdV ((3)HT-incorporation) were compared to AdV-DNAemia. A total of 44/47 patients did not evidence AdV-DNAemia. Thirty-two of 44 (73%) developed CD4-mediated interferon-gamma (IFN-γ) responses to AdV (median 0.36 CD4/µL of blood) since the first month post-HSCT (n = 11: 8 genoidentical and 3 unrelated) or the third month (n = 21 additional patients). At 3 months, both incidence and level intensities of AdV-specific CD4 appeared similar in genoidentical and unrelated BMT (70% and 80%; 0.36 and 0.21 CD4/µL, respectively) and not statistically different from age-matched controls (76%; 1.35 CD4/µL), whereas cord blood transplanted patients exhibited similar incidence but higher level intensities (67%; 1.49 CD4/µL). Polyfunctional (IL2 + IFN-γ) and proliferative responses appeared later, after the third month. Three of 4 9/10 HLA-matched unrelated HSCT that did not develop immunity to AdV presented chemotherapy-resistant AdV-DNAemia at 3 to 5 months post-hematopoietic stem cell transplantation (HSCT). Two were successfully treated with AdV-specific CTL infusion. Monitoring, since month 1 post-HSCT, of IFN-γ-secreting AdV-specific CD4 appears suitable for early detection of at-risk patients especially in 9/10 HLA-matched unrelated HSCT and preferable to monitoring of more delayed IL2- and proliferative responses.

Contribution of HLA-A/B/C/DRB1/DQB1 common haplotypes to donor search outcome in unrelated hematopoietic stem cell transplantation.

In unrelated hematopoietic stem cell transplantation (HSCT), the prediction of donor search outcome at the time of search initiation is of great value for the physicians to delineate the strategy of patient care. The probability of finding an unrelated donor is high for patients who carry at least 1 of the 10 most common HLA haplotypes in Caucasians. As only 10% to 20% patients respond to this criterion, here we aimed at finding additional common haplotypes to improve the prediction of a successful search. HLA broad HLA-A/B/DRB1 haplotypes that were observed with frequencies ≥0.19% in patient families of European origin and that split into ≤2 predominant 4-digit HLA-A/B/C/DRB1/DQB1 haplotypes were considered as common. Carriage of at least 1 of those in 168 patients of various geographic areas with no family donor was confronted to the chance of finding ≥9/10 HLA-matched unrelated donors. Fifty common 4-digit haplotypes were identified. A higher (P < 5 × 10(-6)) chance of finding a suitable donor was found for 55 of 170 (32%) recipients that carried at least 1 of these common haplotypes. Up to now, estimates classified patients into ≥3 groups of probability with ≥1 intermediate group of poor utility for the clinicians. Considering carriage of these common haplotypes together with the frequencies of alleles and of B/C and DRB1/DQB1 associations, which are carried by patient HLA haplotypes, we could classify the patients into 2 groups of probability with a 98% and 26% chance of finding a donor, respectively. Prediction of search outcome could be improved by including the 50 most common HLA haplotypes in the current approaches.

Outcome of children treated with haematopoietic-stem cell transplantations from donors expressing the rare C77G variant of the PTPRC (CD45) gene.

The uncommon C77G polymorphism of the Protein-Tyrosine Phosphatase (PTPRC) gene (PTPRC; previously termed CD45) could confer an increased risk of immunopathology. This study compared the outcome of children following human leucocyte antigen-matched unrelated haematopoïetic-stem cell transplantations (HSCT) from donors carrying (C77G cases: n = 8) or not (controls: n = 36) the PTPRC C77G polymorphism. Transmission of the PTPRC C77G polymorphism through the graft was suggested by unusual CD45RA phenotype in the donors and/or in the recipients after, but not before HSCT. Restriction-Fragment Length Polymorphism and sequencing confirmed the polymorphism. Overall survival rates were similar in C77G cases and controls (63% vs. 61%). Acute leukaemia relapse tended to be less frequent in C77G cases (0% vs. 32%; P = 0·09). Among recipients surviving ≥ 30 d, acute GVHD (aGVHD) ≥ grade 2 tended to be more frequent (100% vs. 58%; P = 0·07) and the rate of steroid-refractory or -dependant aGVHD higher (67% vs. 28%) in C77G cases. Finally, extensive chronic GVHD tended to occur more frequently (40% vs. 9%) in C77G cases. Recovery of lymphocyte subsets and virus-specific CD4 was similar in C77G cases and controls while interleukin 2 (IL2)-responses through CD3 stimulation were higher in C77G cases (P = 0·004). In conclusion, HSCT from PTPRC C77G donors could increase GVHD risk without compromising overall survival. Altered IL2-responses could be involved in this process.

Development of cytomegalovirus and adenovirus-specific memory CD4 T-cell functions from birth to adulthood.

Age-related changes in memory CD4 T cells (CD4) are poorly known. To address this issue, CD4 proliferative and cytokine responses to an anti-CD3 monoclonal (CD3), to cytomegalovirus (CMV), and to adenovirus (AdV) were assessed in 57 children (age, 0.07-17.16 y) and 17 adults. Results showed i) accumulation of memory CD4 with aging, with 2-3 times more central-memory T cell (TCM; CD45RA/CD62L) than effector-memory T cell (TEM; CD45RA/62L) CD4 at any age. ii) In children older than 2 y, CMV-specific CD4-secreting IFNγ alone predominated over CD4-secreting IL2 + IFNγ and a continuous increase, with aging, in IFNγ responses to the virus was observed. In contrast, in AdV infection, CD4-secreting IL2 + IFNγ predominated and IFNγ responses to the virus reached adult levels from 3 y of age. iii) In children aged 0-2 y, lower total IFNγ responses to CMV (p < 0.02), AdV (p = 0.05), and CD3 (p < 0.01) and lower IFNγ + IL2-responses (p = 0.1, p < 0.02, p < 0.05, respectively) contrasted with no decrease in CD4-secreting IFNγ alone. Defective proliferative responses to AdV (p = 0.03) were also observed. In conclusion, the development of memory CD4 differed in acute AdV and persistent CMV infections. Young age seemed to depress mostly polyfunctional (IL2 + IFNγ secreting) CD4 in both infections.

Performance of the QuantiFERON-TB Gold Assay Among HIV-infected Children With Active Tuberculosis in France.

BACKGROUND: Data regarding the use of QuantiFERON to assist the diagnosis of active tuberculosis (TB) in HIV-infected children are limited, especially in countries with low incidence of TB/HIV coinfection. METHODS: QuantiFERON results were analyzed in 63 HIV-infected children who presented to our hospital in Paris, France. Seventeen HIV-uninfected children with active TB (4 culture-confirmed) were included for comparison. RESULTS: The 63 HIV-infected children (median age: 11 yr) had 113 QuantiFERON tests. Thirty-four (54%) were born in sub-Saharan Africa. Vertical HIV transmission was documented for 50 of 52 (96%) and stage III HIV-infection for 30 of 50 children (60%). Over the study period, active TB was diagnosed in 7 of 63 HIV-infected children (3 culture-confirmed). Additional ongoing or previous opportunistic infections were present in 4 of 7. QuantiFERON results were positive in 2 of 7 HIV-infected children with active TB (sensitivity: 29%) and 16 of 17 HIV-uninfected children with active TB (sensitivity: 94%). At initial QuantiFERON testing of the 63 HIV-infected children, 8 (13%) had positive results (1, active TB; 5, latent TB; 2, previous TB) and 51 (81%) had negative results. Of 33 children with repeat testing after an initially positive or negative result, the only change was one conversion from a negative to a positive result at the onset of active TB. The 4 children (6%) with indeterminate quantiFERON results had a concomitant opportunistic infection. Results of repeat testing after clinical stabilization were negative in all 4. CONCLUSIONS: QuantiFERON testing performed poorly for active TB diagnosis in this series of children with advanced HIV infection.

HLA alleles and haplotypes in French North African immigrants.

Human leukocyte antigen (HLA) haplotypes (n = 187) were genotyped and assigned by the mode of inheritance in migrant families from North Africa who reside in the Paris, France, area. The distribution of alleles and haplotypes in that population was compared with the one obtained in a control population of ancient French natives residing in the same area (248 independent haplotypes also assigned by the mode of inheritance were studied). The results in migrants reveal the following: (1) a higher diversity in the distribution of HLA-A and -DRB1 alleles; (2) lower frequencies of alleles common in our region, such as A*0201 B*1501, B*4001, and DRB1*0401 and increased frequencies of minor subtypes, such as A*3002 and DRB1*0402; and (3) distinct distributions of B/Cw, DRB1/DQB1 or B/Cw/DRB1/DQB1 haplotypes. The results also revealed that the four most frequent five-allele haplotypes in controls i.e., HLA-A*0101/B*0801/Cw*0701/DRB1*0301/DQB1*0201; A*0301/B*0702/Cw*0702/DRB1*1501/DQB1*0602 (both of Indo-Celtic origin); A*2902/B*4403/Cw*1601/DRB1*0701/DQB1*0202 (frequent in Western-Europeans); and A*0201/B*1501/Cw*0304/DRB1*0401/DQB1*0302, represent 10.5% of the total haplotypes in controls but 1.6% in North Africans. Conversely, 9 five-allele haplotypes in multiple copy in North Africans (among which A*3002/B*1801/Cw*0501/DRB1*0301/DQB1*0201 of Paleo-North African origin and A*0201/B*0702/Cw*0702/DRB1*1501/DQB1*0602 of ancient European and Paleo-North African origin) represent 9.6% of the total haplotypes in North Africans but 2.4% in controls. These results thus suggest a low degree of admixture between the two populations.

[Polymorphism in HLA and KIR genes and the impact on hematopoietic stem cell transplantation outcomes and unrelated donor selection: Guidelines from the Francophone Society of Bone Marrow Transplantation and Cellular Therapy (SFGM-TC)]. / Polymorphisme des gènes HLA et KIR et l'impact sur le devenir de la greffe et le choix du donneur non apparenté de cellules souche hématopoïétiques : recommandations de la Société francophone de greffe de moelle et de thérapie cellulaire (SFGM-TC).

In an attempt to harmonize clinical practices among French hematopoietic stem cell transplantation centers, the Francophone Society of Bone Marrow Transplantation and Cellular Therapy (SFGM-TC) held its sixth annual workshop series in September 2015 in Lille. This event brought together practitioners from across the country with the purpose of offering careful analysis of published studies on clinical practice issues that remain to be disputed. This article addresses the impact of HLA and KIR gene polymorphism on the outcome of the transplantation in order to optimize unrelated donor selection.

Altered cytokine profiles in children with indeterminate quantiferon results and common infections.

OBJECTIVES: An increased rate of indeterminate quantiferon results (low IFN-γ release in the phytohemagglutinin-stimulated tube) has been reported in children with clinical signs compatible with tuberculosis but with the final diagnosis of infectious diseases different from tuberculosis. Here, we addressed the mechanisms involved and assessed potential alternative biomarkers to overcome indeterminate quantiferon results under these conditions. METHODS: Cytokine concentrations were measured in residual plasma from quantiferon assays performed in immunocompetent children (cases, median age: 3 years 9 months) with indeterminate results and community acquired pneumonia (n = 7) or meningoencephalitis (n = 1). Controls were age-matched immunocompetent children with determinate quantiferon results (infected with mycobacterium tuberculosis, n = 7 or not, n = 8). RESULTS: Lower IFN-γ expression in phytohemagglutinin-stimulated cultures from cases was accompanied by lower Th1 (IL-2, TNF-α, IP-10) and Th2 (IL-5, IL-13), but similar IL-10 secretion capacities as the controls. CONCLUSIONS: A state of hyporesponsiveness that resembles the concept of immunoparalysis in severe infection was observed in children with milder infections. Though IP-10, IL-2, IL-5 and IL-13 were confirmed as promising alternative biomarkers for discriminating controls with and without tuberculosis in this study, defective induction of these biomarkers by phytohemagglutinin in cases precluded their usefulness in overcoming quantiferon indeterminate results in the above-mentioned clinical conditions.

Cytokine responses to quantiferon peptides in pediatric tuberculosis: a pilot study.

OBJECTIVES: Detailed understanding of tuberculosis (TB) immunopathology and cytokine/chemokine responses can ultimately lead to the development of new diagnostic tools, especially useful in children where TB diagnosis remains challenging. METHODS: Nineteen cytokine/chemokine responses to Mycobacterium tuberculosis (M.tb) antigens were analyzed in 47 children distributed as follow: 28 with TB-disease (TD), 12 with latent TB and 7 uninfected controls. All the cytokines and chemokines were quantified in a multiplexed microsphere-based assay by using residual plasma from the quantiFERON kit (IFNγ release assay). RESULTS: IP-10, IL-2, IL-5 and IL-13 were among the best cytokines to diagnose infection as related by the area under ROC curve for IP-10 (0.96, 95%CI: 0.91-1.00), IL-2 (0.98, 95%CI: 0.93-1.02), IL-5 (0.91, 95%CI: 0.81-1.01) and IL-13 (0.97, 95%CI: 0.93-1.00). None of the 5 biomarkers, however, discriminated TB-disease from latent-TB. Finally, lower IL-5 (p = 0.02) and IL-13 (p = 0.02) levels were observed in severe opposed to non-severe TB. CONCLUSION: These results suggest that IP-10, IL-2, IL-5 and IL-13 may find a diagnostic application in pediatric tuberculosis and argue against the paradigm of a negative influence of Th2 responses in severe pediatric M.tb infection.

QuantiFERON to diagnose infection by Mycobacterium tuberculosis: performance in infants and older children.

OBJECTIVES: QuantiFERON value to diagnose tuberculosis (TB) in young children remains to be clarified. To this aim QF-TB-IT performance was evaluated in a large series of immunocompetent children that were stratified according to age and clinical conditions. METHODS: QF-TB-IT reactivity was analyzed in 226 immunocompetent children (0-15 years old): 31 were uninfected despite TB contact; 51 presented TB disease; 39 had Latent TB (LTBI) and 105 had TB disease suspected but an alternative diagnosis (TB excluded). RESULTS: QF-TB-IT specificity was 100% in TB excluded. In TB disease, low sensitivity of QF-TB-IT in infants (40%) increased with aging (77% in 1-<5 years and 82% in 5-<15 years old subgroups). In LTBI, agreement between TST and QF-TB-IT was 0% in infants, 40% in 1-<5 years and 57% in children >5 years old. Finally, the incidence of indeterminate results was high (24%) in children <5 years old with TB excluded, especially with non-TB pneumonitis (61%), but was low (0-6%) regardless of age group in TB disease, LTBI and uninfected contact cases. CONCLUSIONS: In our low burden country, i) QF-TB-IT specificity was 100%, ii) QF-TB-IT sensitivity was low in infants but commensurable to adult values in older children, and iii) indeterminate results mostly relied on ongoing infections unrelated to TB.

Cellular and humoral immunity elicited by influenza vaccines in pediatric hematopoietic-stem cell transplantation.

Immunity induced by influenza vaccines following hematopoietic stem-cell transplantation (HSCT) is poorly understood. Here, 14 pediatric recipients (mean age: 6 years) received H1N1 (n=9) or H1N1/H3N2 (n=5) vaccines at a median of 5.7 months post-HSCT (HLA-identical related bone-marrow graft: 10/14). Fourteen clinically-matched non-vaccinated recipients were included as controls. Cellular response to vaccination was assessed by a T-cell proliferation assay. Humoral response was assessed by H1N1-specific antibody titration. IL2 and IFNγ responses to influenza were also evaluated by an intracellular cytokine accumulation method for some of the recipients. Higher proliferative responses to H1N1 (p=0.0001) and higher H1N1-specific antibody titers (p<0.02) were observed in vaccines opposed to non-vaccinated recipients. In some cases, proliferative responses to H1N1 developed while at the same time antibody titers did not reach protective (≥1:40) levels. Most recipients vaccinated with only the H1N1 strain had proliferative responses to both H1N1 and H3N2 (median stimulation index H1N1: 96, H3N2: 126 in responders). Finally, IL2 responses predominated over IFNγ responses (p<0.02) to influenza viruses in responders. In conclusion, H1N1 vaccination induced substantial cell-mediated immunity, and to a lesser extent, humoral immunity at early times post-HSCT. H1N1/H3N2 T-cell cross-reactivity and protective (IL2) rather than effector (IFNγ) cytokinic profiles were elicited.

Interferon-gamma release assay performance for diagnosing tuberculosis disease in 0- to 5-year-old children.

QuantiFERON-TB Gold In-Tube performance was evaluated in 19 French immunocompetent children (0.29-5.36 years; median: 1.52) with active tuberculosis. The rate of indeterminates results was 0/19 and the rates of positivity were 6/10 and 9/9 in <2 and 2- to 5-year-old children, respectively. QuantiFERON-TB Gold In-Tube in association with tuberculin skin test could improve diagnosis of tuberculosis even in young children.

Comparison of CD8+ T Cell responses to cytomegalovirus between human fetuses and their transmitter mothers.

BACKGROUND: The mechanisms responsible for the increased susceptibility of fetuses to cytomegalovirus (CMV) were studied by comparing CD8(+) T cell responses to the virus in susceptible fetuses to those in their comparatively more resistant mothers. METHODS: Included in the study were 16 transmitter mothers who underwent seroconversion during the first trimester of pregnancy as well as their fetuses, who were positive for CMV in amniotic fluid by polymerase chain reaction at 17-19 weeks of gestation. Fetal and maternal blood samples were collected between the 22nd and 39th week of gestation. Cytotoxic T lymphocytes (CTLs) that had activated (HLA-DR(+)), effector/memory (CD28(-)), and memory (CD18(high)) phenotypes; that stained with the HLA-A2/pp65 or the HLA-B7/pp65 multimer; and that secreted interferon (IFN)- gamma were enumerated by flow cytometry. Viral loads were determined simultaneously. RESULTS: The results showed (1) similar levels of activated, effector/memory, and memory CTLs in fetuses and mothers but a smaller pp65-specific CTL pool in fetuses (median, 0.015% vs. 0.99%; P=.003); (2) similar percentages of CTLs secreting IFN- gamma after stimulation with ionomycin/phorbol myristate acetate in fetuses and mothers but lower percentages of CTLs secreting IFN- gamma after stimulation with a CD3 monoclonal antibody in fetuses (median, 1% vs. 14%; P=.01); and (3) higher viral loads (mean, 17,290 vs. <250 genome equivalents/mL) in fetuses. CONCLUSION: Impaired viral clearance might be related to a defective expansion of the pp65-specific CTL pool and/or to the immaturity of IFN- gamma -secreting cells in fetuses.

Mechanisms involved in the low-level regeneration of CD4+ cells in HIV-1-infected patients receiving highly active antiretroviral therapy who have prolonged undetectable plasma viral loads.

BACKGROUND: Persistent low CD4(+) cell counts are observed in 5%-27% of patients treated for human immunodeficiency virus (HIV)-1 infection despite their having prolonged undetectable plasma viral loads. METHODS: To understand the possible mechanisms of this discordant immunological situation, a prospective transsectional case-control study was designed. HIV-1-infected subjects who had a plasma viral load <200 copies/mL for >1 year were considered to be case patients if their CD4(+) cell count was <250/mm(3); control patients had CD4(+) cell counts >500/mm(3) and were matched by sex, age, and nadir CD4(+) cell count to case patients. T cell proliferation after stimulation with various antigens, T cell subset counts, T cell rearrangement excision circles (TRECs), T cells undergoing apoptosis, cytokines influencing apoptosis, and cellular proviral DNA and plasma viral RNA persistence were assessed. RESULTS: Compared with the 19 control patients, the 19 case patients had undistinguishable lymphoproliferative responses to candidin and cytomegalovirus, fewer naive CD4(+) cells (CD45RA(+)62L(+), 23%+/-13% vs. 47%+/-14%; P<.0001), lower thymic output (1.28 vs. 3.95 TRECs/microL of blood; P=.0015), increased cell death by apoptosis (spontaneous, 23.2%+/-8.3% vs. 11.9%+/-8.4% [P=.02]; Fas induced, 38.6%+/-13.7% vs. 16.4%+/-8.0% [P=.004]), higher levels of plasma soluble tumor necrosis factor receptor II (9.6 vs. 5.3 ng/mL; P=.0058), and undistinguishable plasma HIV-1 and cellular proviral DNA loads. CONCLUSIONS: The mechanisms responsible for the low-level regeneration of CD4(+) cells involve, at least, deficiency in the regeneration of central CD4(+) cells and excessive apoptosis.

Cellular immune response of fetuses to cytomegalovirus.

Primary infection with cytomegalovirus (CMV) in immunocompetent hosts is accompanied with activation and differentiation of naive CD8(+) T cells to effector/memory cells secreting interferon-gamma (IFN-gamma). Alteration of these responses during the perinatal period is suggested by a higher rate of CMV diseases in congenital infection. For addressing this issue, immunologic investigations were performed in 15 fetuses (22-36 wk of gestation) with documented congenital CMV infection. Results show that cellular immune responses can be detected as soon as the 22nd week of gestation (the youngest fetus analyzed). Compared with age-matched control subjects, infected fetuses evidence a dramatic increase in the percentages of activated and terminally differentiated CD8 T cells. Indeed, median percentages (interquartile range) of HLA-DR(+) and of CD28(-)CD8(+) T cells were 24% (19-34) and 38% (24-52), respectively in infected fetuses versus 3% (0-4) for each subset in control subjects. In addition, the percentages of T cells secreting IFN-gamma after in vitro stimulation with phorbol myristate acetate and ionomycin was significantly higher in infected fetuses [10% (5-25)] than in healthy fetuses [0.8% (0.6-1.2)] with IFN-gamma being mostly secreted by CD8(+) T cells and to a lesser extend by CD4(+) T cells. These cellular immune responses have clear similarities with responses previously reported in adults. Cellular immunity to CMV, however, might not be fully functional in fetuses. Indeed, the number of T cells capable of secreting IFN-gamma is strikingly lower after in vitro stimulation with the CMV-specific antigen than after in vitro stimulation with phorbol myristate acetate/ionomycin that bypasses signaling through the T-cell receptor.