T-Cell Responses in Adults During Natural Respiratory Syncytial Virus Infection

Background

The pathogenesis of respiratory syncytial virus (RSV) in older adults may be due to age-related T-cell immunosenescence. Thus, we evaluated CD4 and CD8 T-cell responses during RSV infection in adults across the age spectrum.

Methods

Peripheral blood mononuclear cells collected during RSV infection in adults, age 26-96 years, were stimulated with live RSV and peptide pools representing F, M, NP, and G proteins and analyzed by flow cytometry.

Results

There were no significant age-related differences in frequency of CD4+ T cells synthesizing interferon (IFN)γ, interleukin (IL)2, IL4, IL10, or tumor necrosis factor (TNF)α or in CD8+IFNγ+ T cells. IL4+CD4+ T-cell numbers were low, as were IL13 and IL17 responses. However, in univariate analysis, CD4 T-cell IFNγ, IL2, IL4, IL10, and TNFα responses and CD8+IFNγ+ T cells were significantly increased with more severe illness requiring hospitalization. In multivariate analysis, viral load was also associated with increased T-cell responses.

Conclusions

We found no evidence of diminished RSV-specific CD4 or CD8 T-cell responses in adults infected with RSV. However, adults with severe disease seemed to have more robust CD4 and CD8 T-cell responses during infection, suggesting that disease severity may have a greater association with T-cell responses than age.

Flow-based sorting of neonatal lymphocyte populations for transcriptomics analysis

RATIONALE

Emerging data suggest an important role for T lymphocytes in the pathogenesis of chronic lung disease in preterm infants. Comprehensive assessment of the lymphocyte transcriptome may identify biomarkers and mechanisms of disease.

METHODS

Small volume peripheral blood samples were collected from premature infants enrolled with consent in the Prematurity and Respiratory Outcomes Program (PROP), at the time of discharge from the hospital. Blood samples were collected at two sites and shipped to a central laboratory for processing. Peripheral blood mononuclear cells (PBMCs) were isolated by Ficoll-Hypaque gradient centrifugation and separated into individual lymphocyte cell types by fluorescence-activated cell sorting. Gating strategies were optimized to ensure reproducible recovery of highly purified lymphocyte populations over a multi-year recruitment period. RNA was isolated from sorted cells and characterized by high-throughput sequencing (RNASeq).

RESULTS

Blood volumes averaged 2.5ml, and sufficient PBMCs were collected from 165 of the 246 samples obtained (67%) from the 277 recruited subjects to complete sorting and RNASeq analysis on the resulting sorted cells. The number of total lymphocytes per ml of blood in the neonatal subjects was approximately 4 million/ml. Total lymphocyte frequencies recovered following sort varied widely among subjects, as did the frequency of individual lymphocyte and NK cell sub-populations. RNA yield from sorted cells varied according to cell type, but RNA of sufficient quantity and quality was recovered to enable RNASeq.

SUMMARY

Our results describe a validated procedure for the generation of genome-wide expression data from isolated lymphocyte sub-populations obtained from newborn blood.

Stability of T cell phenotype and functional assays following heparinized umbilical cord blood collection

Umbilical cord blood has been used for a wide variety of immunologic investigations including assessments of developmental perturbations by antenatal exposures. Recent advances in multiparameter flow cytometry have allowed finer characterization of lymphocyte phenotype and function, revealing important differences between the fetal and adult immune systems. The degree of variability between human subjects confounds the ability to draw firm conclusions. Artifacts resulting from processing techniques exacerbate this variability. The unpredictable nature of deliveries, especially of premature infants, makes it difficult to control variables such as timing of umbilical cord mononuclear cell (UCMC) isolation and method of collection. Additionally, in multicenter studies dependent on central processing, delays are inevitable. However, little available literature describes systematic testing of the degree to which processing variations affect UCMC phenotype and function. Using multiparameter flow cytometry, we tested the effect of collection technique and length of time prior to UCMC isolation on T cell phenotype and function, with the goal of creating a standardized operating procedure for a multicenter investigation. The study also provides a benchmark data set including extensive surface and functional phenotyping of umbilical cord T cells. UCMC isolation delay of up to 24 h produced similar T cell phenotype and function as tested by in vitro SEB stimulation. There were few statistically significant differences between time points based on data medians. We conclude that, for the purpose of immunologic investigations, a 24-h time delay from sample collection to mononuclear cell isolation does not introduce a significant degree of variation in T cell phenotype and function when adhering to strict standard operating procedures.

Effect of delay from sample collection to umbilical cord mononuclear cell isolation on T cell phenotype and function. (174.20)

Background: The unpredictable nature of deliveries makes it difficult to control timing of umbilical cord mononuclear cell (UCMC) isolation. Our study tested the effect of time delay from umbilical cord collection to UCMC isolation on T cell phenotype and function. Methods: Cord blood was drawn from 15 healthy term deliveries using a standardized collection method. Each sample was divided and processed immediately, 24 hours and 48 hours after collection. Samples were analyzed using flow cytometry for phenotype and cytokine secretion, with and without in vitro stimulation. Comparisons were made to determine differences in variation and median cell frequencies over time. Results: Viability and recovery were >92% for all time-points. There was a decrease after 48 hours for CD56+ and CD3+ frequencies. CD4+ T cells showed differences after 24 hours in 4 of 23 subpopulations, and 8 subpopulations after 48 hours. No differences were seen with cytokine positive frequencies for IFNg, TNFa, IL17, or IL4/5/13 after 24 and 48 hours, but there was a decrease in IL2 and increase in MIP1β frequencies for CD4+ T cells. IL2 alone was increased for CD8+ T cells after 24 and 48 hours. Variation analysis showed high assay reproducibility, and subject-subject variation exceeded time delay variation for most populations. Conclusion: A 24-hour delay prior to UCMC isolation does not significantly change phenotype or function of most cord T cell subsets. A 48-hour delay may affect study results.

Follicular lymphoma tumor-infiltrating T-helper (T(H)) cells have the same polyfunctional potential as normal nodal T(H) cells despite skewed differentiation

The follicular lymphoma (FL) T-cell microenvironment plays a critical role in the biology of this disease. We therefore determined the lineage, differentiation state, and functional potential of FL-infiltrating CD4(+) T-helper cells (T(H)) compared with reactive and normal lymph node (NLN) T(H) cells. Relative to NLNs, FL cells have decreased proportions of naive and central memory but increased proportions of effector memory T(H) cells. We further show differences in the distribution and anatomical localization of CXCR5(+) T(H) populations that, on the basis of transcription factor analysis, include both regulatory and follicular helper T cells. On Staphylococcus enterotoxin-B stimulation, which stimulates T cells through the T-cell receptor, requires no processing by APCs, and can overcome regulator T cell-mediated suppression, the proportion of uncommitted primed precursor cells, as well as T(H)2 and T(H)17 cells is higher in FL cells than in reactive lymph nodes or NLNs. However, the proportion of T(H)1 and polyfunctional T(H) cells (producing multiple cytokines simultaneously) is similar in FL cells and NLNs. These data suggest that, although T(H)-cell differentiation in FL is skewed compared with NLNs, FL T(H) cells should have the same intrinsic ability to elicit antitumor effector responses as NLN T(H) cells when tumor suppressive mechanisms are attenuated.

Human follicular lymphoma CD39+-infiltrating T cells contribute to adenosine-mediated T cell hyporesponsiveness

Our previous work has demonstrated that human follicular lymphoma (FL) infiltrating T cells are anergic, in part due to suppression by regulatory T cells. In this study, we identify pericellular adenosine, interacting with T cell-associated G protein-coupled A(2A/B) adenosine receptors (AR), as contributing to FL T cell hyporesponsiveness. In a subset of FL patient samples, treatment of lymph node mononuclear cells (LNMC) with specific A(2A/B) AR antagonists results in an increase in IFN-gamma or IL-2 secretion upon anti-CD3/CD28 Ab stimulation, as compared with that seen without inhibitors. In contrast, treatment with an A(1) AR antagonist had no effect on cytokine secretion. As the rate limiting step for adenosine generation from pericellular ATP is the ecto-ATPase CD39, we next show that inhibition of CD39 activity using the inhibitor ARL 67156 partially overcomes T cell hyporesponsiveness in a subset of patient samples. Phenotypic characterization of LNMC demonstrates populations of CD39-expressing CD4(+) and CD8(+) T cells, which are overrepresented in FL as compared with that seen in normal or reactive nodes, or normal peripheral blood. Thirty percent of the FL CD4(+)CD39(+) T cells coexpress CD25(high) and FOXP3 (consistent with regulatory T cells). Finally, FL or normal LNMC hydrolyze ATP in vitro, in a dose- and time-dependent fashion, with the rate of ATP consumption being associated with the degree of CD39(+) T cell infiltration. Together, these results support the finding that the ATP-ectonucleotidase-adenosine system mediates T cell anergy in a human tumor. In addition, these studies suggest that the A(2A/B) AR as well as CD39 are novel pharmacological targets for augmenting cancer immunotherapy.