Zeb2 drives the formation of CD11c+ atypical B cells to sustain germinal centers that control persistent infection.

CD11c+ atypical B cells (ABCs) are an alternative memory B cell lineage associated with immunization, infection, and autoimmunity. However, the factors that drive the transcriptional program of ABCs have not been identified, and the function of this population remains incompletely understood. Here, we identified candidate transcription factors associated with the ABC population based on a human tonsillar B cell single-cell dataset. We identified CD11c+ B cells in mice with a similar transcriptomic signature to human ABCs, and using an optimized CRISPR-Cas9 knockdown screen, we observed that loss of zinc finger E-box binding homeobox 2 (Zeb2) impaired ABC formation. Furthermore, ZEB2 haplo-insufficient Mowat-Wilson syndrome (MWS) patients have decreased circulating ABCs in the blood. In Cd23Cre/+Zeb2fl/fl mice with impaired ABC formation, ABCs were dispensable for efficient humoral responses after Plasmodium sporozoite immunization but were required to control recrudescent blood-stage malaria. Immune phenotyping revealed that ABCs drive optimal T follicular helper (TFH) cell formation and germinal center (GC) responses and they reside at the red/white pulp border, likely permitting better access to pathogen antigens for presentation. Collectively, our study shows that ABC formation is dependent on Zeb2, and these cells can limit recrudescent infection by sustaining GC reactions.

Tracking the clonal dynamics of SARS-CoV-2-specific T cells in children and adults with mild/asymptomatic COVID-19.

Children infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) develop less severe coronavirus disease 2019 (COVID-19) than adults. The mechanisms for the age-specific differences and the implications for infection-induced immunity are beginning to be uncovered. We show by longitudinal multimodal analysis that SARS-CoV-2 leaves a small footprint in the circulating T cell compartment in children with mild/asymptomatic COVID-19 compared to adult household contacts with the same disease severity who had more evidence of systemic T cell interferon activation, cytotoxicity and exhaustion. Children harbored diverse polyclonal SARS-CoV-2-specific naïve T cells whereas adults harbored clonally expanded SARS-CoV-2-specific memory T cells. A novel population of naïve interferon-activated T cells is expanded in acute COVID-19 and is recruited into the memory compartment during convalescence in adults but not children. This was associated with the development of robust CD4+ memory T cell responses in adults but not children. These data suggest that rapid clearance of SARS-CoV-2 in children may compromise their cellular immunity and ability to resist reinfection.

Parallel analysis of multiple human memory CD4+ T-cell subsets within antigen-specific responses using cell proliferation dyes.

Activation induced marker (AIM) assays are being used increasingly to measure antigen-specific T-cell responses, but this activation can alter cell lineage defining phenotypic markers. We aimed to extend the utility of AIM assays to enable pre-activation defined cell populations to be tracked and quantified within T-cell memory responses. We sorted three ex vivo CD4+ T-cell populations prior to any activation using well defined ex vivo lineage surface marker combinations. These populations were memory non-Tregs, CD39+ Tregs and CD39neg Tregs, although any three memory CD4+ T-cell populations able to be isolated by cell surface markers could potentially be tracked. These cells were labeled with three distinct fluorescent cell proliferation dyes (CFSE, CellTrace Violet and Cell Proliferation Dye eF670) and then all autologous PBMCs were reconstituted maintaining ex vivo cell ratios and CD25/OX40 AIM assays performed with CMV and HSV antigens. This approach enabled tracking of pre-defined cell populations within antigen stimulated responses using both activation marker and cell proliferation readouts. We confirmed that although CD39+ Tregs comprise a substantial proportion of AIM assay responses, they do not make substantial contributions to the proliferative response. This extends the utility of AIM assays to enable parallel analysis of the relative contribution of several CD4+ memory T-cell subsets to recall responses.

High titre neutralizing antibodies in response to SARS-CoV-2 infection require RBD-specific CD4 T cells that include proliferative memory cells.

Background: Long-term immunity to SARS-CoV-2 infection, including neutralizing antibodies and T cell-mediated immunity, is required in a very large majority of the population in order to reduce ongoing disease burden. Methods: We have investigated the association between memory CD4 and CD8 T cells and levels of neutralizing antibodies in convalescent COVID-19 subjects. Findings: Higher titres of convalescent neutralizing antibodies were associated with significantly higher levels of RBD-specific CD4 T cells, including specific memory cells that proliferated vigorously in vitro. Conversely, up to half of convalescent individuals had low neutralizing antibody titres together with a lack of receptor binding domain (RBD)-specific memory CD4 T cells. These low antibody subjects had other, non-RBD, spike-specific CD4 T cells, but with more of an inhibitory Foxp3+ and CTLA-4+ cell phenotype, in contrast to the effector T-bet+, cytotoxic granzymes+ and perforin+ cells seen in RBD-specific memory CD4 T cells from high antibody subjects. Single cell transcriptomics of antigen-specific CD4+ T cells from high antibody subjects similarly revealed heterogenous RBD-specific CD4+ T cells that comprised central memory, transitional memory and Tregs, as well as cytotoxic clusters containing diverse TCR repertoires, in individuals with high antibody levels. However, vaccination of low antibody convalescent individuals led to a slight but significant improvement in RBD-specific memory CD4 T cells and increased neutralizing antibody titres. Interpretation: Our results suggest that targeting CD4 T cell epitopes proximal to and within the RBD-region should be prioritized in booster vaccines.

Elevation of cell-associated HIV-1 transcripts in CSF CD4+ T cells, despite effective antiretroviral therapy, is linked to brain injury.

Antiretroviral therapy (ART) can attain prolonged undetectable HIV-1 in plasma and cerebrospinal fluid (CSF), but brain injury remains prevalent in people living with HIV-1 infection (PLHIV). We investigated cell-associated (CA)-HIV-1 RNA transcripts in cells in CSF and blood, using the highly sensitive Double-R assay, together with proton Magnetic Resonance Spectroscopy (1H MRS) of major brain metabolites, in sixteen PLHIV. 14/16 CSF cell samples had quantifiable CA-HIV-1 RNA, at levels significantly higher than in their PBMCs (median 9,266 vs 185 copies /106 CD4+ T-cells; p<0.0001). In individual PLHIV, higher levels of HIV-1 transcripts in CSF cells were associated with greater brain injury in the frontal white matter (Std ß=-0.73; p=0.007) and posterior cingulate (Std ß=-0.61; p=0.03). 18-colour flow cytometry revealed that the CSF cells were 91% memory T-cells, equally CD4+ and CD8+ T-cells, but fewer B cells (0.4 %), and monocytes (3.1%). CXCR3+CD49d+integrin ß7-, CCR5+CD4+ T-cells were highly enriched in CSF, compared with PBMC (p <0.001). However, CA-HIV-1 RNA could not be detected in 10/16 preparations of highly purified monocytes from PBMC, and was extremely low in the other six. Our data show that elevated HIV-1 transcripts in CSF cells were associated with brain injury, despite suppressive ART. The cellular source is most likely memory CD4+ T cells from blood, rather than trafficking monocytes. Future research should focus on inhibitors of this transcription to reduce local production of potentially neurotoxic and inflammatory viral products.

Haematopoietic Stem Cell Transplantation Results in Extensive Remodelling of the Clonal T Cell Repertoire in Multiple Sclerosis.

Autologous haematopoietic stem cell transplantation (AHSCT) is a vital therapeutic option for patients with highly active multiple sclerosis (MS). Rates of remission suggest AHSCT is the most effective form of immunotherapy in controlling the disease. Despite an evolving understanding of the biology of immune reconstitution following AHSCT, the mechanism by which AHSCT enables sustained disease remission beyond the period of lymphopenia remains to be elucidated. Auto-reactive T cells are considered central to MS pathogenesis. Here, we analyse T cell reconstitution for 36 months following AHSCT in a cohort of highly active MS patients. Through longitudinal analysis of sorted naïve and memory T cell clones, we establish that AHSCT induces profound changes in the dominant T cell landscape of both CD4+ and CD8+ memory T cell clones. Lymphopenia induced homeostatic proliferation is followed by clonal attrition; with only 19% of dominant CD4 (p <0.025) and 13% of dominant CD8 (p <0.005) clones from the pre-transplant repertoire detected at 36 months. Recovery of a thymically-derived CD4 naïve T cell repertoire occurs at 12 months and is ongoing at 36 months, however diversity of the naïve populations is not increased from baseline suggesting the principal mechanism of durable remission from MS after AHSCT relates to depletion of putative auto-reactive clones. In a cohort of MS patients expressing the MS risk allele HLA DRB1*15:01, public clones are probed as potential biomarkers of disease. AHSCT appears to induce sustained periods of disease remission with dynamic changes in the clonal T cell repertoire out to 36 months post-transplant.

Sustained immunotolerance in multiple sclerosis after stem cell transplant.

OBJECTIVE: Autologous haematopoietic stem cell transplantation (AHSCT) has the potential to induce sustained periods of disease remission in multiple sclerosis (MS), which is an inflammatory disease of the central nervous system (CNS) characterised by demyelination and axonal degeneration. However, the mechanisms associated with durable treatment responses in MS require further elucidation. METHODS: To characterise the longer term immune reconstitution effects of AHSCT at 24 and 36 months (M) post-transplant, high-dimensional immunophenotyping of peripheral blood mononuclear cells from 22 MS patients was performed using two custom-designed 18-colour flow cytometry panels. RESULTS: The higher baseline frequencies of specific pro-inflammatory immune cells (T-helper-17 (Th17) cells, mucosal-associated invariant T-cells and CNS-homing T-conventional (T-conv) cells observed in MS patients were decreased post-AHSCT by 36M. This was accompanied by a post-AHSCT increase in frequencies and absolute counts of immunoregulatory CD56hi natural killer cells at 24M and terminally differentiated CD8+ CD28- CD57+ cells until 36M. A sustained increase in the proportion of naïve B-cells, with persistent depletion of memory B-cells and plasmablasts was observed until 36M. Reconstitution of the B-cell repertoire was accompanied by a reduction in the frequency of circulating T-follicular helper cells (cTfh) expressing programmed cell death-1 (PD1+ ) at 36M. Associations between frequency dynamics and clinical outcomes indicated only responder patients to exhibit a decrease in Th17, CNS-homing T-conv and PD1+ cTfh pro-inflammatory subsets at 36M, and an increase in CD39+ T-regulatory cells at 24M. INTERPRETATION: AHSCT induces substantial recalibration of pro-inflammatory and immunoregulatory components of the immune system of MS patients for up to 36M post-transplant.

Early expansion of CD38+ICOS+ GC Tfh in draining lymph nodes during influenza vaccination immune response.

T follicular helper (Tfh) cells provide critical help to B cells during the germinal center (GC) reaction to facilitate generation of protective humoral immunity. Accessing the human lymph node (LN) to study the commitment of CD4 T cells to GC Tfh cell differentiation during in vivo vaccine responses is difficult. We used ultrasound guided fine needle biopsy to monitor recall responses in axillary LNs to seasonal influenza vaccination in healthy volunteers. Specific expansion of GC cell subsets occurred exclusively within draining LNs five days postvaccination. Draining LN GC Tfh and precursor-Tfh cells express higher levels of CD38, ICOS, and Ki67, indicating they were significantly more activated, motile, and proliferating, compared to contralateral LN cells. These observations provide insight into the early expansion phase of the human Tfh lineage within LNs during a vaccine induced memory response and highlights early LN immune responses may not be reflected in the periphery.

HIV-1 viral blips are associated with repeated and increasingly high levels of cell-associated HIV-1 RNA transcriptional activity.

OBJECTIVE: Some HIV+ patients, virally suppressed on ART, show occasional 'blips' of detectable HIV-1 plasma RNA. We used a new highly sensitive assay of cell-associated HIV-1 RNA to measure transcriptional activity in PBMCs and production of infectious virus from the viral reservoir, in patients with and without 'blips'. DESIGN/METHODS: RNA and DNA extracted from cells in 6 ml of peripheral blood, from suppressed patients with one to two 'blip' episodes over the past 2 years of ART (n = 55), or no 'blips' (n = 52), were assayed for HIV-1 RNA transcripts and proviral DNA targeting the highly conserved 'R' region of the LTR. Follow-up samples were also collected. Purified CD4+ T cells were cultured with anti-CD3/CD28/CD2 T-cell activator to amplify transcription and measure replication competent virus. RESULTS: HIV-1 RNA transcripts ranged from 1.3 to 5415 copies/106 white blood cells. 'Blip' patients had significantly higher levels vs. without blips (median 192 vs. 49; P = 0.0007), which correlated with: higher levels of inducible transcripts after activation in vitro, sustained higher HIV-1 transcription levels in follow-up samples along with increasing HIV-1 DNA in some, and production of replication-competent HIV-1. CONCLUSION: Viral 'blips' are significant reflecting higher transcriptional activity from the reservoir and contribute to the reservoir over time. This sensitive assay can be used in monitoring the size and activity of the HIV-1 reservoir and will be useful in HIV-1 cure strategies.

The Role of ZEB2 in Human CD8 T Lymphocytes: Clinical and Cellular Immune Profiling in Mowat-Wilson Syndrome.

The Zeb2 gene encodes a transcription factor (ZEB2) that acts as an important immune mediator in mice, where it is expressed in early-activated effector CD8 T cells, and limits effector differentiation. Zeb2 homozygous knockout mice have deficits in CD8 T cells and NK cells. Mowat-Wilson syndrome (MWS) is a rare genetic disease resulting from heterozygous mutations in ZEB2 causing disease by haploinsufficiency. Whether ZEB2 exhibits similar expression patterns in human CD8 T cells is unknown, and MWS patients have not been comprehensively studied to identify changes in CD8 lymphocytes and NK cells, or manifestations of immunodeficiency. By using transcriptomic assessment, we demonstrated that ZEB2 is expressed in early-activated effector CD8 T cells of healthy human volunteers following vaccinia inoculation and found evidence of a role for TGFß-1/SMAD signaling in these cells. A broad immunological assessment of six genetically diagnosed MWS patients identified two patients with a history of recurrent sinopulmonary infections, one of whom had recurrent oral candidiasis, one with lymphopenia, two with thrombocytopenia and three with detectable anti-nuclear antibodies. Immunoglobulin levels, including functional antibody responses to protein and polysaccharide vaccination, were normal. The MWS patients had a significantly lower CD8 T cell subset as % of lymphocytes, compared to healthy controls (median 16.4% vs. 25%, p = 0.0048), and resulting increased CD4:CD8 ratio (2.6 vs. 1.8; p = 0.038). CD8 T cells responded normally to mitogen stimulation in vitro and memory CD8 T cells exhibited normal proportions of subsets with important tissue-specific homing markers and cytotoxic effector molecules. There was a trend towards a decrease in the CD8 T effector memory subset (3.3% vs. 5.9%; p = 0.19). NK cell subsets were normal. This is the first evidence that ZEB2 is expressed in early-activated human effector CD8 T cells, and that haploinsufficiency of ZEB2 in MWS patients had a slight effect on immune function, skewing T cells away from CD8 differentiation. To date there is insufficient evidence to support an immunodeficiency occurring in MWS patients.

Preservation of Gastrointestinal Mucosal Barrier Function and Microbiome in Patients With Controlled HIV Infection.

Background: Despite successful ART in people living with HIV infection (PLHIV) they experience increased morbidity and mortality compared with HIV-negative controls. A dominant paradigm is that gut-associated lymphatic tissue (GALT) destruction at the time of primary HIV infection leads to loss of gut integrity, pathological microbial translocation across the compromised gastrointestinal barrier and, consequently, systemic inflammation. We aimed to identify and measure specific changes in the gastrointestinal barrier that might allow bacterial translocation, and their persistence despite initiation of antiretroviral therapy (ART). Method: We conducted a cross-sectional study of the gastrointestinal (GIT) barrier in PLHIV and HIV-uninfected controls (HUC). The GIT barrier was assessed as follows: in vivo mucosal imaging using confocal endomicroscopy (CEM); the immunophenotype of GIT and circulating lymphocytes; the gut microbiome; and plasma inflammation markers Tumour Necrosis Factor-α (TNF-α) and Interleukin-6 (IL-6); and the microbial translocation marker sCD14. Results: A cohort of PLHIV who initiated ART early, during primary HIV infection (PHI), n=5), and late (chronic HIV infection (CHI), n=7) infection were evaluated for the differential effects of the stage of ART initiation on the GIT barrier compared with HUC (n=6). We observed a significant decrease in the CD4 T-cell count of CHI patients in the left colon (p=0.03) and a trend to a decrease in the terminal ileum (p=0.13). We did not find evidence of increased epithelial permeability by CEM. No significant differences were found in microbial translocation or inflammatory markers in plasma. In gut biopsies, CD8 T-cells, including resident intraepithelial CD103+ cells, did not show any significant elevation of activation in PLHIV, compared to HUC. The majority of residual circulating activated CD38+HLA-DR+ CD8 T-cells did not exhibit gut-homing integrins α4ß7, suggesting that they did not originate in GALT. A significant reduction in the evenness of species distribution in the microbiome of CHI subjects (p=0.016) was observed, with significantly higher relative abundance of the genus Spirochaeta in PHI subjects (p=0.042). Conclusion: These data suggest that substantial, non-specific increases in epithelial permeability may not be the most important mechanism of HIV-associated immune activation in well-controlled HIV-positive patients on antiretroviral therapy. Changes in gut microbiota warrant further study.

CD73+ CD127high Long-Term Memory CD4 T Cells Are Highly Proliferative in Response to Recall Antigens and Are Early Targets in HIV-1 Infection.

HIV-1 infection rapidly leads to a loss of the proliferative response of memory CD4+ T lymphocytes, when cultured with recall antigens. We report here that CD73 expression defines a subset of resting memory CD4+ T cells in peripheral blood, which highly express the α-chain of the IL-7 receptor (CD127), but not CD38 or Ki-67, yet are highly proliferative in response to mitogen and recall antigens, and to IL-7, in vitro. These cells also preferentially express CCR5 and produce IL-2. We reasoned that CD73+ memory CD4+ T cells decrease very early in HIV-1 infection. Indeed, CD73+ memory CD4+ T cells comprised a median of 7.5% (interquartile range: 4.5-10.4%) of CD4+ T cells in peripheral blood from healthy adults, but were decreased in primary HIV-1 infection to a median of 3.7% (IQR: 2.6-6.4%; p = 0.002); and in chronic HIV-1 infection to 1.9% (IQR: 1.1-3%; p < 0.0001), and were not restored by antiretroviral therapy. Moreover, we found that a significant proportion of CD73+ memory CD4+ T cells were skewed to a gut-homing phenotype, expressing integrins α4 and ß7, CXCR3, CCR6, CD161 and CD26. Accordingly, 20% of CD4+ T cells present in gut biopsies were CD73+. In HIV+ subjects, purified CD73+ resting memory CD4+ T cells in PBMC were infected with HIV-1 DNA, determined by real-time PCR, to the same level as for purified CD73-negative CD4+ T cells, both in untreated and treated subjects. Therefore, the proliferative CD73+ subset of memory CD4+ T cells is disproportionately reduced in HIV-1 infection, but, unexpectedly, their IL-7 dependent long-term resting phenotype suggests that residual infected cells in this subset may contribute significantly to the very long-lived HIV proviral DNA reservoir in treated subjects.

Altered Immune Reconstitution in Allogeneic Stem Cell Transplant Recipients With Human Immunodeficiency Virus (HIV).

BACKGROUND: Persons living with human immunodeficiency virus (HIV) are at elevated risk of developing the malignant diseases that require allogeneic stem cell transplantation (ASCT). Recent data suggest that these individuals are also at an elevated risk of certain complications post-ASCT. This risk may result from preexisting HIV-related factors affecting dynamics of immune reconstitution post-ASCT. However, to date, there has been little work describing the dynamics of immune reconstitution post-ASCT in persons with HIV and none comparing these data to controls without HIV. METHODS: We assessed T-cell reconstitution in 6 ASCT with HIV recipients (HIV+ASCT) compared to a control population of 21 ASCT without HIV recipients. In a subset of HIV+ASCT recipients we performed additional flow cytometry profiling of CD8+ T-cell subsets and antigen specificity of reconstituting CD4+ and CD8+ T cells. RESULTS: We observe no difference in post-ASCT CD4+ T cells between HIV+ASCT and HIV-negative ASCT recipients, despite much lower pre-ASCT CD4+ T-cell counts in the HIV+ASCT group. In contrast, we observed significantly higher CD8+ T-cell numbers in the HIV+ASCT group post-ASCT. The reconstituting CD8+ T-cells were predominantly CD45RO+, whereas homing markers and antigen specificity of these cells varied between participants. CONCLUSION: This study represents the most extensive characterization of immune-reconstitution post-ASCT in persons with HIV, and the first to our knowledge to compare these data to ASCT controls without HIV. The results indicate that immune reconstitution in this group can be affected by preexisting HIV infection and post-ASCT antigen exposure.

Mapping the extent of heterogeneity of human CCR5+ CD4+ T cells in peripheral blood and lymph nodes.

BACKGROUND: CD4 T cells that express the chemokine receptor, CCR5, are the most important target of HIV-1 infection, but their functions, phenotypes and anatomical locations are poorly understood. We aimed to use multiparameter flow cytometry to better define the full breadth of these cells. METHODS: High-parameter fluorescence flow and mass cytometry were optimized to analyse subsets of CCR5 memory CD4 T cells, including CD25CD127 Tregs, CXCR3CCR6- Th1-like, CCR6CD161CXCR3- Th17-like, integrins α4ß7 gut-homing, CCR4 skin-homing, CD62L lymph node-homing, CD38HLA-DR activated cells, and CD27-CD28- cytotoxic T lymphocytes, in a total of 22 samples of peripheral blood, ultrasound-guided fine needle biopsies of lymph nodes and excised tonsils. CCR5 antigen-specific CD4 T cells were studied using the OX40 flow-based assay. RESULTS: 10-20% of CCR5 memory CD4 T cells were Tregs, 10-30% were gut-homing, 10-30% were skin-homing, 20-40% were lymph node-homing, 20-50% were Th1-like and 20-40% were Th17-like cells. Up to 30% were cytotoxic T lymphocytes in CMV-seropositive donors, including cells that were either CCR5Granzyme K or CCR5Granzyme B. When all possible phenotypes were exhaustively analysed, more than 150 different functional and trafficking subsets of CCR5 CD4 T cells were seen. Moreover, a small population of resident CD69Granzyme KCCR5 CD4 T cells was found in lymphoid tissues. CMV- and Mycobacterium tuberculosis-specific CD4 T cells were predominantly CCR5. CONCLUSION: These results reveal for the first time the prodigious heterogeneity of function and trafficking of CCR5 CD4 T cells in blood and in lymphoid tissue, with significant implications for rational approaches to prophylaxis for HIV-1 infection and for purging of the HIV-1 reservoir in those participants already infected.

Circulating gluten-specific, but not CMV-specific, CD39+ regulatory T cells have an oligoclonal TCR repertoire.

OBJECTIVES: Understanding the T cell receptor (TCR) repertoire of regulatory CD4+ T-cell (Treg) populations is important for strategies aiming to re-establish tolerance in autoimmune diseases. We studied circulating deamidated gluten-epitope-specific CD39+ Tregs in patients with coeliac disease following an oral gluten challenge, and we used cytomegalovirus (CMV)-specific CD39+ Tregs from healthy controls as a comparator population. METHODS: We used the OX40 assay to isolate antigen-specific Tregs by induced surface co-expression of CD25, OX40 and CD39. RACE PCR amplification and Sanger sequencing of the TCR ß chain were used to analyse repertoire diversity. RESULTS: We found that, following oral gluten challenge, circulating gluten-specific CD39+ Tregs had an oligoclonal TCR repertoire that contained public clonotypes. Conversely, the TCR repertoire of CMV-epitope-specific CD39+ Tregs from healthy controls was polyclonal. DISCUSSION: These data indicate that a biased TCR repertoire is not inherent to CD39+ Tregs, and, in this case, is apparently driven by the HLA-DQ2.5-restricted deamidated gluten peptide in coeliac disease patients. CONCLUSION: This is the first assessment of the TCR repertoire within circulating human Tregs specific for foreign antigen. These data enhance our understanding of antigen-specific CD4+ responses in the settings of chronic inflammation and infection and may help guide immunomonitoring strategies for CD4+ T cell-based therapies, particularly for coeliac disease.

Possible clearance of transfusion-acquired nef/LTR-deleted attenuated HIV-1 infection by an elite controller with CCR5 Δ32 heterozygous and HLA-B57 genotype.

BACKGROUND: Subject C135 is one of the members of the Sydney Blood Bank Cohort, infected in 1981 through transfusion with attenuated nef/3' long terminal repeat (LTR)-deleted HIV-1, and has maintained undetectable plasma viral load and steady CD4 cell count, in the absence of therapy. Uniquely, C135 combines five factors separately associated with control of viraemia: nef/LTR-deleted HIV-1, HLA-B57, HLA-DR13, heterozygous CCR5 Δ32 genotype and vigorous p24-stimulated peripheral blood mononuclear cell (PBMC) proliferation. Therefore, we studied in detail viral burden and immunological responses in this individual. METHODS: PBMC and gut and lymph node biopsy samples were analysed for proviral HIV-1 DNA by real-time and nested PCRs, and nef/LTR alleles by nested PCR. HIV-specific antibodies were studied by Western blotting, and CD4+ and CD8+ T lymphocyte responses were measured by proliferation and cytokine production in vitro. RESULTS: PBMC samples from 1996, but not since, showed amplification of nef alleles with gross deletions. Infectious HIV-1 was never recovered. Proviral HIV-1 DNA was not detected in recent PBMC or gut or lymph node biopsy samples. C135 has a consistently weak antibody response and a substantial CD4+ T cell proliferative response to a previously described HLA-DR13-restricted epitope of HIV-1 p24 in vitro, which augmented a CD8+ T cell response to an immunodominant HLA-B57-restricted epitope of p24, while his T cells show reduced levels of CCR5. CONCLUSIONS: Subject C135's early PCR and weak antibody results are consistent with limited infection with a poorly replicating nef/LTR-deleted strain of HIV-1. With his HLA-B57-restricted gag-specific CD8 and helper HLA-DR13-restricted CD4 T cell proliferative responses, C135 appears to have cleared his HIV-1 infection 37 years after transfusion.

HIV-1 DNA Is Maintained in Antigen-Specific CD4+ T Cell Subsets in Patients on Long-Term Antiretroviral Therapy Regardless of Recurrent Antigen Exposure.

Memory CD4+ T cells (mCD4s) containing integrated HIV DNA are considered the main barrier to a cure for HIV infection. Here, we analyzed HIV DNA reservoirs in antigen-specific subsets of mCDs to delineate the mechanisms by which HIV reservoirs persist during antiretroviral therapy (ART). HIV Gag, cytomegalovirus (CMV), and tetanus toxoid (TT)-specific mCD4s were isolated from peripheral blood samples obtained from 11 individual subjects, 2-11 years after commencing ART. Antigen-specific mCD4s were identified by the sensitive OX40 assay and purified by cell sorting. Total HIV DNA levels were quantified by real-time PCR, and clonal viral sequences generated from mCD4 subsets and pre-ART plasma samples. Quantitative results and sequence analysis were restricted to five and three study participants, respectively, which was likely due to the low frequency of the antigen-specific mCD4s and relatively low HIV DNA proviral loads. Median HIV Gag-, CMV-, and TT-specific mCD4s were 0.61%, 2.46%, and 0.78% of total mCD4s, and they contained a median of 2.50, 2.38, and 2.55 log10 copies of HIV DNA per 106 cells, respectively. HIV DNA sequences were derived from antigen-specific mCD4s clustered with sequences derived from pre-ART plasma samples. There was a trend toward increased viral diversity in clonal viral sequences derived from CMV-specific mCD4s relative to TT-specific mCD4s. Despite limitations, this study provides direct evidence that HIV reservoirs persist in memory CD4+ T cell subsets maintained by homeostatic proliferation (TT) and adds to growing evidence against viral evolution during ART. Similar future studies require techniques that sample diverse HIV reservoirs and with improved sensitivity.

Prospective phase II clinical trial of autologous haematopoietic stem cell transplant for treatment refractory multiple sclerosis.

BACKGROUND: Autologous haematopoietic stem cell transplantation (AHSCT) has been explored as a therapeutic intervention in multiple sclerosis (MS) over the last two decades; however, prospective clinical trials of the most common myeloablative conditioning regimen, BEAM, are limited. Furthermore, patient selection, optimal chemotherapeutic regimen and immunological changes associated with disease response require ongoing exploration. We present the outcomes, safety and immune reconstitution (IR) of patients with active, treatment refractory MS. METHODS: This study was a single-centre, phase II clinical trial of AHSCT for patients with active relapsing remitting (RRMS) and secondary progressive MS (SPMS). Patients underwent AHSCT using BEAM (carmustine, etoposide, cytarabine, melphalan)+antithymocyte globulin chemotherapeutic regimen. OUTCOMES: The primary outcome was event-free survival (EFS); defined as no clinical or radiological relapses and no disability progression. Multiparameter flow cytometry was performed for evaluation of post-transplant IR in both MS and lymphoma patients receiving the same chemotherapy regimen. RESULTS: Thirty-five patients (20 RRMS, 15 SPMS) completed AHSCT, with a median follow-up of 36 months (range 12-66). The median Expanded Disability Status Scores (EDSS) was 6 (2-7) and patients had failed a median of 4 (2-7) disease modifying therapies. 66% failed treatment with natalizumab. EFS at 3 years was 60%, (70% RRMS). Sustained improvement in EDSS was seen in 15 (44%) of patients. There was no treatment-related mortality. A sustained rise in CD39+ T regulatory cells, immunosuppressive CD56hi natural killer cells and ablation of proinflammatory mucosal-associated invariant T cells was seen for 12 months following AHSCT in patients with MS. These changes did not occur in patients with lymphoma receiving the same chemotherapy for AHSCT. CONCLUSIONS: The EFS in our MS cohort is significantly greater than other high-efficacy immunosuppressive therapies and similar to other AHSCT studies despite a more heavily pretreated cohort. TRIAL REGISTRATION NUMBER: ACTRN12613000339752.