Minimal information about T cell assays: the process of reaching the community of T cell immunologists in cancer and beyond

Tolerogenic dendritic cell reporting: Has a minimum information model made a difference?

Minimum information models are reporting frameworks that describe the essential information that needs to be provided in a publication, so that the work can be repeated or compared to other work. In 2016, Minimum Information about Tolerogenic Antigen-Presenting cells (MITAP) was created to standardize the reporting on tolerogenic antigen-presenting cells, including tolerogenic dendritic cells (tolDCs). tolDCs is a generic term for dendritic cells that have the ability to (re-)establish immune tolerance; they have been developed as a cell therapy for autoimmune diseases or for the prevention of transplant rejection. Because protocols to generate these therapeutic cells vary widely, MITAP was deemed to be a pivotal reporting tool by and for the tolDC community. In this paper, we explored the impact that MITAP has had on the tolDC field. We did this by examining a subset of the available literature on tolDCs. Our analysis shows that MITAP is used in only the minority of relevant papers (14%), but where it is used the amount of metadata available is slightly increased over where it is not. From this, we conclude that MITAP has been a partial success, but that much more needs to be done if standardized reporting is to become common within the discipline.

The need and benefit of immune monitoring to define patient and disease heterogeneity, mechanisms of therapeutic action and efficacy of intervention therapy for precision medicine in type 1 diabetes

The current standard of care for type 1 diabetes patients is limited to treatment of the symptoms of the disease, insulin insufficiency and its complications, not its cause. Given the autoimmune nature of type 1 diabetes, immunology is critical to understand the mechanism of disease progression, patient and disease heterogeneity and therapeutic action. Immune monitoring offers the key to all this essential knowledge and is therefore indispensable, despite the challenges and costs associated. In this perspective, I attempt to make this case by providing evidence from the past to create a perspective for future trials and patient selection.

T cell immunity is key to the pandemic endgame: How to measure and monitor it

As vaccine deployment improves the healthcare emergency status caused by the SARS-CoV-2 pandemic, we need reliable tools to evaluate the duration of protective immunity at a global scale. Seminal studies have demonstrated that while neutralizing antibodies can protect us from viral infection, T cell-mediated cellular immunity provides long-term protection from severe COVID-19, even in the case of emerging new variants of concern (VOC). Indeed, the emergence of VOCs, able to substantially escape antibodies generated by current vaccines, has made the analysis of correlates of humoral protection against infection obsolete. The focus should now shift towards immunological correlates of protection from disease based on quantification of cellular immunity. Despite this evidence, an assessment of T cell responses is still overlooked. This is largely due to technical challenges and lack of validated diagnostic tests. Here, we review the current state of the art of available tests to distinguish between SARS-CoV-2 antigen-specific Tcells and non-antigen specific T-cells. These assays range from the analysis of the T cell-receptor (TCR) diversity (i.e. Immunoseq and MHC tetramer staining) to the detection of functional T cell activation (i.e. ICS, AIM, Elispot, ELLA, dqTACT, etc.) either from purified Peripheral Blood Mononuclear Cells (PBMCs) or whole blood. We discuss advantages and disadvantages of each assay, proposing their ideal use for different scopes. Finally, we argue how it is paramount to deploy cheap, standardized, and scalable assays to measure T cell functionality to fill this critical diagnostic gap and manage these next years of the pandemic.

Tumor-Infiltrating Lymphocytes and Their Role in Solid Tumor Progression

Tumor-infiltrating lymphocytes (TIL) are an important component of the tumor environment. Their role in tumor growth and progression has been debated for decades. Today, emphasis has shifted to beneficial effects of TIL for the host and to therapies optimizing the benefits by reducing immune suppression in the tumor microenvironment. Evidence indicates that when TILs are present in the tumor as dense aggregates of activated immune cells, tumor prognosis and responses to therapy are favorable. Gene signatures and protein profiling of TIL at the population and single-cell levels provide clues not only about their phenotype and numbers but also about TIL potential functions in the tumor. Correlations of the TIL data with clinicopathological tumor characteristics, clinical outcome, and patients' survival indicate that TILs exert influence on the disease progression, especially in colorectal carcinomas and breast cancer. At the same time, the recognition that TIL signatures vary with time and cancer progression has initiated investigations of TIL as potential prognostic biomarkers. Multiple mechanisms are utilized by tumors to subvert the host immune system. The balance between pro- and antitumor responses of TIL largely depends on the tumor microenvironment, which is unique in each cancer patient. This balance is orchestrated by the tumor and thus is shifted toward the promotion of tumor growth. Changes occurring in TIL during tumor progression appear to serve as a measure of tumor aggressiveness and potentially provide a key to selecting therapeutic strategies and inform about prognosis.

Association between absolute lymphocyte count and overall mortality in patients with surgically resected gastric cancer

BACKGROUND/AIMS

Lymphocytes are an important component of the cell-mediated immune system. As lymphopenia is reportedly associated with poor prognoses in patients with various cancers, we investigated this notion in patients who underwent curative gastrectomy.

METHODS

We retrospectively analyzed the association between absolute lymphocyte count (ALC) and prognosis in patients with stage I-III gastric cancer who underwent curative surgical resection. Ever lymphopenic patients were defined as those with ALCs < 1,000/μL at any time post-diagnosis except within 30 days post-surgery. Adjusted multivariable regression models were used to evaluate the associations between lymphopenia and overall mortality, gastric cancer-specific mortality, and disease-free survival.

RESULTS

We investigated 1,222 patients diagnosed between January 2011 and December 2015. Fifty-six patients (4.6%) were lymphopenic at diagnosis and nearly one-quarter (24.8%) were ever lymphopenic with a mean minimum ALC of 640/μL. Older age (odds ratio [OR], 1.02) and higher stage (stage III vs. I; OR, 3.01) were positively associated with ever lymphopenia. On multivariable analysis, ever lymphopenia predicted higher overall mortality (hazard ratio [HR], 1.83; p = 0.008), higher gastric cancer-specific mortality (HR, 1.58; p = 0.048), and shorter disease-free survival (HR, 1.83; p = 0.006). The 5-year gastric cancer-specific mortality rates for ever- and never lymphopenic patients were 10.9% and 3.7%, respectively; their 5-year cumulative recurrence rates were 15.1% and 4.6%, respectively.

CONCLUSION

This study demonstrate that ever lymphopenia is independent prognostic factor for overall mortality and recurrence in patients with potentially curable gastric cancer; hence, ALCs may be a biomarker for predicting the prognoses of patients with stage I-III gastric cancer who had curative gastrectomy.

Trial watch: Peptide vaccines in cancer therapy

Prophylactic vaccination constitutes one of the most prominent medical achievements of history. This concept was first demonstrated by the pioneer work of Edward Jenner, dating back to the late 1790s, after which an array of preparations that confer life-long protective immunity against several infectious agents has been developed. The ensuing implementation of nation-wide vaccination programs has de facto abated the incidence of dreadful diseases including rabies, typhoid, cholera and many others. Among all, the most impressive result of vaccination campaigns is surely represented by the eradication of natural smallpox infection, which was definitively certified by the WHO in 1980. The idea of employing vaccines as anticancer interventions was first theorized in the 1890s by Paul Ehrlich and William Coley. However, it soon became clear that while vaccination could be efficiently employed as a preventive measure against infectious agents, anticancer vaccines would have to (1) operate as therapeutic, rather than preventive, interventions (at least in the vast majority of settings), and (2) circumvent the fact that tumor cells often fail to elicit immune responses. During the past 30 y, along with the recognition that the immune system is not irresponsive to tumors (as it was initially thought) and that malignant cells express tumor-associated antigens whereby they can be discriminated from normal cells, considerable efforts have been dedicated to the development of anticancer vaccines. Some of these approaches, encompassing cell-based, DNA-based and purified component-based preparations, have already been shown to exert conspicuous anticancer effects in cohorts of patients affected by both hematological and solid malignancies. In this Trial Watch, we will summarize the results of recent clinical trials that have evaluated/are evaluating purified peptides or full-length proteins as therapeutic interventions against cancer.

Evaluation of T-activated proteins as recall antigens to monitor Epstein-Barr virus and human cytomegalovirus-specific T cells in a clinical trial setting

BACKGROUND

Pools of overlapping synthetic peptides are routinely used for ex vivo monitoring of antigen-specific T-cell responses. However, it is rather unlikely that these peptides match those resulting from naturally processed antigens. T-activated proteins have been described as immunogenic and more natural stimulants, since they have to pass through antigen processing and comprise activation of all clinically relevant effector cell populations.

METHODS

We performed comparative analysis of numbers and cytokine expression pattern of CD4 and CD8 T cells after stimulation with recombinant, urea-formulated T-activated EBV-BZLF1, -EBNA3A, and HCMV-IE1, and -pp65 proteins or corresponding overlapping peptide pools. Freshly isolated and cryopreserved PBMC of 30 EBV- and 19 HCMV-seropositive and seven EBV- and HCMV-seronegative subjects were stimulated ex vivo and analysed for IFN-γ, TNF and IL-2 production by flow cytometry-based intracellular cytokine staining.

RESULTS

T-activated proteins showed a high specificity of 100% (EBV-BZLF1, HCMV-IE1, and -pp65) and 86% (EBV-EBNA3A), and a high T-cell stimulatory capacity of 73-95% and 67-95% using freshly isolated and cryopreserved PBMC, respectively. The overall CD4 T-cell response rates in both cohorts were comparable after stimulation with either T-activated protein or peptide pools with the exception of lower numbers of CD8 T cells detected after stimulation with T-activated EBV-EBNA3A- (p = 0.038) and HCMV-pp65- (p = 0.0006). Overall, the number of detectable antigen-specific T cells varied strongly between individuals. Cytokine expression patterns in response to T-activated protein and peptide pool-based stimulation were similar for CD4, but significantly different for CD8 T-cell responses.

CONCLUSION

EBV and HCMV-derived T-activated proteins represent innovative, highly specific recall antigens suitable for use in immunological endpoint assays to evaluate success or failure in immunotherapy clinical trials (e.g. to assess the risk of EBV and/or HCMV reactivation after allogenic hematopoietic stem cell transplantation). T-activated proteins could be of particular importance, if an impaired antigen processing (e.g. in a post-transplant setting) must be taken into account.

Identification of new MUC1 epitopes using HLA-transgenic animals: implication for immunomonitoring

BACKGROUND

The success of immunotherapeutics in oncology and the search for further improvements has prompted revisiting the use of cancer vaccines. In this context, knowledge of the immunogenic epitopes and the monitoring of the immune response cancer vaccines generate are essential. MUC1 has been considered one of the most important tumor associated antigen for decades.

METHODS

To identify HLA-restricted MUC1 peptides we used eight human MHC class I transgenic mouse lines, together covering more than 80% of the human population. MUC1 peptides were identified by vaccinating each line with full length MUC1 coding sequences and using an IFNγ ELIspot restimulation assay. Relevant peptides were tested in a flow cytometry-based tetramer assay and for their capacity to serve as target in an in vivo killing assay.

RESULTS

Four previously identified MUC1 peptides were confirmed and five are described here for the first time. These nine peptide-MHC combinations were further characterized. Six gave above-background tetramer staining of splenocytes from immunized animals and three peptides were induced more than 5% specific in vivo killing.

CONCLUSIONS

These data describe for the first time five new HLA class I-restricted peptides and revisit some that were previously described. They also emphasize the importance of using in vivo/ex vivo models to screen for immunogenic peptides and define the functions for individual peptide-HLA combinations.

The presence of human papillomavirus (HPV) in placenta and/or cord blood might result in Th2 polarization

The purpose of this study was to evaluate if an early exposure to human papillomavirus (HPV) during the prenatal period or infancy could result in HPV16-specific T helper (Th) responses resembling those of adults with HPV-induced lesions. We tested HPV16-specific cell-mediated immunity (CMI) in children born with HPV-positive umbilical cord blood and/or placenta or having persistent oral HPV infection and in constantly oral HPV-negative controls. Peripheral blood mononuclear cells from 33 children from the Finnish HPV Family Study cohort (mean age 14.7 years) were stimulated with peptide pools covering the amino acid sequence of the HPV16 E2, E6, and E7 proteins. Lymphocyte proliferation, secretion of cytokines (IFN-γ, TNF-α, IL-2, IL-4, IL-5, IL-10, IL-17A), and the frequency of Foxp3+ regulatory T-cells were determined in relation to the HPV DNA status during a 14-year follow-up. 73.6% of cases and 85.7% of controls responded against HPV16 E2, while reactivity against E6 was found in 10.5 and 35.7%, respectively. The proliferative response against E6 and E7 was more frequent in controls than in cases (p = 0.047). No HPV16-specific CMI response or antibodies were detected in two children with persistent oral HPV16. The profiles of induced cytokines indicated higher levels of IL-5, IL-10, and IL-17A in children with HPV DNA in placenta and/or cord blood than in other children. HPV16-specific CMI is common in HPV DNA-negative children. The cytokine profile in children infected with HPV16 during early life suggests that the viral dose and/or specific environment created by the placenta may have significant impact on the type of HPV-specific immunity.

Validation of biomarkers to predict response to immunotherapy in cancer: Volume I - pre-analytical and analytical validation

Immunotherapies have emerged as one of the most promising approaches to treat patients with cancer. Recently, there have been many clinical successes using checkpoint receptor blockade, including T cell inhibitory receptors such as cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) and programmed cell death-1 (PD-1). Despite demonstrated successes in a variety of malignancies, responses only typically occur in a minority of patients in any given histology. Additionally, treatment is associated with inflammatory toxicity and high cost. Therefore, determining which patients would derive clinical benefit from immunotherapy is a compelling clinical question.

Although numerous candidate biomarkers have been described, there are currently three FDA-approved assays based on PD-1 ligand expression (PD-L1) that have been clinically validated to identify patients who are more likely to benefit from a single-agent anti-PD-1/PD-L1 therapy. Because of the complexity of the immune response and tumor biology, it is unlikely that a single biomarker will be sufficient to predict clinical outcomes in response to immune-targeted therapy. Rather, the integration of multiple tumor and immune response parameters, such as protein expression, genomics, and transcriptomics, may be necessary for accurate prediction of clinical benefit. Before a candidate biomarker and/or new technology can be used in a clinical setting, several steps are necessary to demonstrate its clinical validity. Although regulatory guidelines provide general roadmaps for the validation process, their applicability to biomarkers in the cancer immunotherapy field is somewhat limited. Thus, Working Group 1 (WG1) of the Society for Immunotherapy of Cancer (SITC) Immune Biomarkers Task Force convened to address this need. In this two volume series, we discuss pre-analytical and analytical (Volume I) as well as clinical and regulatory (Volume II) aspects of the validation process as applied to predictive biomarkers for cancer immunotherapy. To illustrate the requirements for validation, we discuss examples of biomarker assays that have shown preliminary evidence of an association with clinical benefit from immunotherapeutic interventions. The scope includes only those assays and technologies that have established a certain level of validation for clinical use (fit-for-purpose). Recommendations to meet challenges and strategies to guide the choice of analytical and clinical validation design for specific assays are also provided.

Minimum information about tolerogenic antigen-presenting cells (MITAP): a first step towards reproducibility and standardisation of cellular therapies

Cellular therapies with tolerogenic antigen-presenting cells (tolAPC) show great promise for the treatment of autoimmune diseases and for the prevention of destructive immune responses after transplantation. The methodologies for generating tolAPC vary greatly between different laboratories, making it difficult to compare data from different studies; thus constituting a major hurdle for the development of standardised tolAPC therapeutic products. Here we describe an initiative by members of the tolAPC field to generate a minimum information model for tolAPC (MITAP), providing a reporting framework that will make differences and similarities between tolAPC products transparent. In this way, MITAP constitutes a first but important step towards the production of standardised and reproducible tolAPC for clinical application.

Validation of an IFNγ/IL2 FluoroSpot assay for clinical trial monitoring

Background

The FluoroSpot assay, an advancement of the ELISpot assay, enables simultaneous measurement of different analytes secreted at a single-cell level. This allows parallel detection of several cytokines secreted by immune cells upon antigen recognition. Easier standardization, higher sensitivity and reduced labour intensity render FluoroSpot assays an interesting alternative to flow-cytometry based assays for analysis of clinical samples. While the use of immunoassays to study immunological primary and secondary endpoints becomes increasingly attractive, assays used require pre-trial validation. Here we describe the assay validation (precision, specificity and linearity) of a FluoroSpot immunological endpoint assay detecting Interferon γ (IFNγ) and Interleukin 2 (IL2) for use in clinical trial immune monitoring.

Methods

We validated an IFNγ/IL2 FluoroSpot assay to determine Epstein-Barr virus (EBV)-specific cellular immune responses (IFNγ, IL2 and double positive IFNγ + IL2 responses), using overlapping peptide pools corresponding to EBV-proteins BZLF1 and EBNA3A. Assay validation was performed using cryopreserved PBMC of 16 EBV-seropositive and 6 EBV-seronegative donors. Precision was assessed by (i) testing 16 donors using three replicates per assay (intra-assay precision/repeatability) (ii) using two plates in parallel (intermediate precision/plate-to-plate variability) and (iii) by performing the assays on three different days (inter-assay precision/reproducibility). In addition, we determined specificity, linearity and quantification limits of the assay. Further we tested precision across the two assay systems, IFNγ/IL2 FluoroSpot and the corresponding enzymatic single cytokine ELISpot.

Results

The validation revealed: (1) a high intra-assay precision (coefficient of variation (CV) 9.96, 8.85 and 13.05 %), intermediate precision (CV 6.48, 10.20 and 12.97 %) and reproducibility (CV 20.81 %, 12,75 % and 12.07 %) depending on the analyte and antigen used; (2) a specificity of 100 %; (3) a linearity with R² values from 0.93 to 0.99 depending on the analyte. The testing of the precision across the two assay systems, adduced a concordance correlation coefficient p_c = 0.99 for IFNγ responses and p_c = 0.93 for IL2 responses, indicating a large agreement between both assay methods.

Conclusions

The validated primary endpoint assay, an EBV peptide pool specific IFNγ/IL2 FluoroSpot assay was found to be suitable for the detection of EBV-specific immune responses subject to the requirement of standardized assay procedure and data analysis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-0932-7) contains supplementary material, which is available to authorized users.

Immuno-oncology combinations: raising the tail of the survival curve

There have been exponential gains in immuno-oncology in recent times through the development of immune checkpoint inhibitors. Already approved by the U.S. Food and Drug Administration for advanced melanoma and non-small cell lung cancer, immune checkpoint inhibitors also appear to have significant antitumor activity in multiple other tumor types. An exciting component of immunotherapy is the durability of antitumor responses observed, with some patients achieving disease control for many years. Nevertheless, not all patients benefit, and efforts should thus now focus on improving the efficacy of immunotherapy through the use of combination approaches and predictive biomarkers of response and resistance. There are multiple potential rational combinations using an immunotherapy backbone, including existing treatments such as radiotherapy, chemotherapy or molecularly targeted agents, as well as other immunotherapeutics. The aim of such antitumor strategies will be to raise the tail on the survival curve by increasing the number of long term survivors, while managing any additive or synergistic toxicities that may arise with immunotherapy combinations. Rational trial designs based on a clear understanding of tumor biology and drug pharmacology remain paramount. This article reviews the biology underpinning immuno-oncology, discusses existing and novel immunotherapeutic combinations currently in development, the challenges of predictive biomarkers of response and resistance and the impact of immuno-oncology on early phase clinical trial design.

Human papillomavirus 16-specific cell-mediated immunity in children born to mothers with incident cervical intraepithelial neoplasia (CIN) and to those constantly HPV negative

Objectives

HPV infections are detected in sexually naive children. This has raised the question about the role of early HPV infections in either protecting or predisposing to further HPV infections. HPV16-specific cell-mediated immunity (CMI) was studied in 10 case-children born to mothers with an incident cervical intraepithelial neoplasia (CIN) diagnosed during their 14-year follow-up (FU), and in 21 children born to mothers, who remained constantly HPV-negative (controls). The mean age of children was 12.3 years.

Methods

Peripheral blood mononuclear cells were isolated from blood and stimulated with peptide pools covering HPV16 E2, E6 and E7. Proliferation of lymphocytes, their secretion of cytokines, and the frequency of regulatory T-cells were determined. The results were correlated with the HPV status and analyzed in a nested case–control setting.

Results

All children, except two controls, displayed CMI against HPV16 E2, E6 and/or E7 peptides associated with type 1 and 2 cytokine secretion. Only two statistically significant differences were found in the nested case–control setting; (1) case-children had a higher TNF-α response to HPV16 E2 (p = 0.004) than controls and (2) controls had no response to HPV16 E7.2 peptide pool while 3/10 case-children had (p = 0.013). Totally, 50 and 57 % of the cases and controls, respectively, had HPV positive oral samples at some FU-visit. In addition, the children without any HPV antibodies before the age of 6 months showed proliferative responses of PBMC after HPV16 exposure more frequently than other children (p = 0.045).

Conclusions

HPV16-specific CMI is common in young, sexually inexperienced children. This suggests that oral HPV infections occur frequently in children. Our results might also explain the previous findings that half of healthy adults demonstrate HPV-specific CMI irrespective of their partner/sexual status.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0733-4) contains supplementary material, which is available to authorized users.

Neonatal regulatory T cells have reduced capacity to suppress dendritic cell function

Regulatory T cells (Treg cells) limit contact between dendritic cells (DCs) and conventional T cells (Tcons), decreasing the formation of aggregates as well as down-modulating the expression of co-stimulatory molecules by DCs, thus decreasing DC immunogenicity and abrogating T-cell activation. Despite the importance of this Treg-cell function, the capacity of Treg cells from term and preterm neonates to suppress DCs, and the suppressive mechanisms they use, are still undefined. We found that, relative to adult Treg cells, activated Treg cells from human neonates expressed lower FOXP3 and CTLA-4, but contained higher levels of cAMP. We developed an in vitro model in which Treg function was measured at a physiological ratio of 1 Treg for 10 Tcon and 1 monocyte-derived DC, as Treg target. Term and preterm Treg cells failed to suppress the formation of DC-Tcon aggregates, in contrast to naïve and memory Treg cells from adults. However, neonatal Treg cells diminished DC and Tcon activation as well as actin polymerization at the immunological synapses. In addition, CTLA-4 and cAMP were the main suppressive molecules used by neonatal Treg. Altogether, both preterm and term neonatal Treg cells appear less functional than adult Treg cells, and this defect is consistent with the general impairment of CD4 cell function in newborns.

Quantitative TCR:pMHC Dissociation Rate Assessment by NTAmers Reveals Antimelanoma T Cell Repertoires Enriched for High Functional Competence

Experimental models demonstrated that therapeutic induction of CD8 T cell responses may offer protection against tumors or infectious diseases providing that T cells have sufficiently high TCR/CD8:pMHC avidity for efficient Ag recognition and consequently strong immune functions. However, comprehensive characterization of TCR/CD8:pMHC avidity in clinically relevant situations has remained elusive. In this study, using the novel NTA-His tag-containing multimer technology, we quantified the TCR:pMHC dissociation rates (koff) of tumor-specific vaccine-induced CD8 T cell clones (n = 139) derived from seven melanoma patients vaccinated with IFA, CpG, and the native/EAA or analog/ELA Melan-A(MART-1)(26-35) peptide, binding with low or high affinity to MHC, respectively. We observed substantial correlations between koff and Ca(2+) mobilization (p = 0.016) and target cell recognition (p < 0.0001), with the latter independently of the T cell differentiation state. Our strategy was successful in demonstrating that the type of peptide impacted on TCR/CD8:pMHC avidity, as tumor-reactive T cell clones derived from patients vaccinated with the low-affinity (native) peptide expressed slower koff rates than those derived from patients vaccinated with the high-affinity (analog) peptide (p < 0.0001). Furthermore, we observed that the low-affinity peptide promoted the selective differentiation of tumor-specific T cells bearing TCRs with high TCR/CD8:pMHC avidity (p < 0.0001). Altogether, TCR:pMHC interaction kinetics correlated strongly with T cell functions. Our study demonstrates the feasibility and usefulness of TCR/CD8:pMHC avidity assessment by NTA-His tag-containing multimers of naturally occurring polyclonal T cell responses, which represents a strong asset for the development of immunotherapy.

Abacavir-reactive memory T cells are present in drug naïve individuals

Background

Fifty-five percent of individuals with HLA-B*57:01 exposed to the antiretroviral drug abacavir develop a hypersensitivity reaction (HSR) that has been attributed to naïve T-cell responses to neo-antigen generated by the drug. Immunologically confirmed abacavir HSR can manifest clinically in less than 48 hours following first exposure suggesting that, at least in some cases, abacavir HSR is due to re-stimulation of a pre-existing memory T-cell population rather than priming of a high frequency naïve T-cell population.

Methods

To determine whether a pre-existing abacavir reactive memory T-cell population contributes to early abacavir HSR symptoms, we studied the abacavir specific naïve or memory T-cell response using HLA-B*57:01 positive HSR patients or healthy controls using ELISpot assay, intra-cellular cytokine staining and tetramer labelling.

Results

Abacavir reactive CD8+ T-cell responses were detected in vitro in one hundred percent of abacavir unexposed HLA-B*57:01 positive healthy donors. Abacavir-specific CD8+ T cells from such donors can be expanded from sorted memory, and sorted naïve, CD8+ T cells without need for autologous CD4+ T cells.

Conclusions

We propose that these pre-existing abacavir-reactive memory CD8+ T-cell responses must have been primed by earlier exposure to another foreign antigen and that these T cells cross-react with an abacavir-HLA-B*57:01-endogenous peptide ligand complex, in keeping with the model of heterologous immunity proposed in transplant rejection.

Cell-Mediated Immunity to AAV Vectors, Evolving Concepts and Potential Solutions

Adeno-associated virus (AAV) vectors are one of the most efficient in vivo gene delivery platforms. Over the past decade, clinical trials of AAV vector-mediated gene transfer led to some of the most exciting results in the field of gene therapy and, recently, to the market approval of an AAV-based drug in Europe. With clinical development, however, it became obvious that the host immune system represents an important obstacle to successful gene transfer with AAV vectors. In this review article, we will discuss the issue of cytotoxic T cell responses directed against the AAV capsid encountered on human studies. While over the past several years the field has acquired a tremendous amount of information on the interactions of AAV vectors with the immune system, a lot of questions are still unanswered. Novel concepts are emerging, such as the relationship between the total capsid dose and the T cell-mediated clearance of transduced cells, the potential role of innate immunity in vector immunogenicity highlighted in preclinical studies, and the cross talk between regulatory and effector T cells in the determination of the outcome of gene transfer. There is still a lot to learn about immune responses in AAV gene transfer, for example, it is not well understood what are the determinants of the kinetics of activation of T cells in response to vector administration, why not all subjects develop detrimental T cell responses following gene transfer, and whether the intervention strategies currently in use to block T cell-mediated clearance of transduced cells will be safe and effective for all gene therapy indications. Results from novel preclinical models and clinical studies will help to address these points and to reach the important goal of developing safe and effective gene therapy protocols to treat human diseases.

Human papillomavirus 16 E2-, E6- and E7-specific T-cell responses in children and their mothers who developed incident cervical intraepithelial neoplasia during a 14-year follow-up of the Finnish Family HPV cohort

Background

Human papillomavirus (HPV) infection has traditionally been regarded as a sexually transmitted disease (STD), but recent evidence implicates that an infected mother can transmit HPV to her newborn during pregnancy, at delivery, perinatal period or later. Given the lack of any studies on HPV-specific immune responses in children, we conducted HPV16-specific cell-mediated immune (CMI) monitoring of the mother-child pairs with known oral and genital HPV follow-up (FU) data since the delivery. In the Finnish Family HPV Study, 10 out of 331 mothers developed incident cervical intraepithelial neoplasia (CIN) during their 14-year FU. Our hypothesis according to the common dogma is that there is no HPV16 specific immune response in offspring of the CIN mother as she/he has not started the sexual life yet.

Methods

We used overlapping 30–35 mer peptides covering the entire HPV16 E2, E6 and E7 protein sequences. Assays for lymphocyte proliferation capacity, cytokine production and HPV16-specific Foxp3 + CD25 + CD4+ regulatory T-cells were performed.

Results

HPV16-specific proliferative T-cell responses were broader in children than in their mothers. Nine of 10 children had responses against both E2 peptide pools compared to only 4 of the 10 mothers. Six of the 10 children and only 2 mothers displayed reactivity to E6 and/or E7. The cytokine levels of IL-2 (p = 0.023) and IL-5 (p = 0.028) induced by all peptide pools, were also higher among children than their mothers. The children of the mothers with incident CIN3 had significantly higher IFN-γ (p = 0.032) and TNF-α (p = 0.008) levels than other children.

Conclusions

Our study is the first to show that also children could have HPV-specific immunity. These data indicate that the children have circulating HPV16-specific memory T-cells which might have been induced by previous HPV16 exposure or ongoing HPV 16 infection.

Specific active immunotherapy with a VEGF vaccine in patients with advanced solid tumors. results of the CENTAURO antigen dose escalation phase I clinical trial

CIGB-247 is a novel cancer therapeutic vaccine that uses a human VEGF variant molecule as antigen, in combination with a bacterial adjuvant. In mice, CIGB-247 has anti-tumor and anti-metastatic effects. The vaccine induces anti-VEGF blocking antibodies and a cellular response targeting tumor cells producing VEGF, and has proven to be safe in mice, rats, rabbits and non-human primates. Herein we report the results of a Phase I clinical trial (code name CENTAURO) where safety, tolerance, and immunogenicity of CIGB-247 were studied in 30 patients with advanced solid tumors, at three antigen dose levels. Individuals were subcutaneously immunized for 8 consecutive weeks with 50, 100 or 400 μg of antigen, and re-immunized on week twelve. On week sixteen, evaluations of safety, tolerance, clinical status, and immunogenicity (seroconversion for anti-VEGF IgG, serum VEGF/KDR-Fc blocking ability, and gamma-IFN ELISPOT with blood cells stimulated in vitro with mutated VEGF) were done. Surviving patients were eligible for off-trial additional 4-week re-immunizations with 400 μg of antigen. Immunogenicity and clinical status were again studied on weeks 25 and 49. Vaccination was shown to be safe at the three dose levels, with only grade 1-2 adverse events. CIGB-247 was immunogenic and higher numbers of individuals positive to the three immune response tests were seen with increasing antigen dose. Off-protocol long-term vaccination produced no additional adverse events or negative changes in immunogenicity. Eleven patients are still alive, with overall survivals ranging from 20 to 24 months. Twelve of the thirty patients exhibited objective clinical benefits, and two individuals have complete responses. Most patients with higher survivals are positive in the three immune response tests. In summary, this is the first clinical testing report of a cancer therapeutic vaccine based on a human VEGF related molecule as antigen. The CIGB-247 vaccine is safe, immunogenic, and merits further clinical development.

REGISTRATION NUMBER AND NAME OF TRIAL REGISTRY

RPCEC00000102. Cuban Public Clinical Trial Registry (WHO accepted Primary Registry). Available from: http://registroclinico.sld.cu/.

The long-term immune response after HPV16 peptide vaccination in women with low-grade pre-malignant disorders of the uterine cervix: a placebo-controlled phase II study

The capacity of a low-dose HPV16 synthetic long-peptide vaccine (HPV16-SLP) to induce an HPV16-specific T-cell response as well as to establish long-term immunologic memory in patients with low-grade abnormalities of the cervix was determined in a placebo-controlled, double-blinded phase II study. In addition, the effect of a booster vaccination after 1 year was evaluated. Patients received either the HPV16-SLP or a placebo at the start of the study. After 1 year, the vaccinated patients were again randomized to receive the HPV16-SLP or a placebo. Patients were followed for 2 years. HPV16-specific T-cell responses were determined in pre- and post-vaccination blood samples by ELISPOT, proliferation assay and cytokine assays. We show that the HPV16-specific T-cell responses detected after vaccination are clearly due to vaccination and that reactivity was maintained for at least 2 years. Interestingly, a booster vaccination after 1 year especially augmented the HPV16-specific Th2 response. Furthermore, pre-existing immunity to HPV16 was associated with a stronger response to vaccination and with more side effects, reflected by flu-like symptoms. We conclude that two low-dose injections of HPV16-SLP can induce a strong and stable HPV16-specific T-cell response that lasts for at least 1 year. If booster vaccination is required, then polarizing adjuvant should be added to maintain the Th1 focus of the vaccine-induced T-cell response.

Overnight resting of PBMC changes functional signatures of antigen specific T- cell responses: impact for immune monitoring within clinical trials

Polyfunctional CD4 or CD8 T cells are proposed to represent a correlate of immune control for persistent viruses as well as for vaccine mediated protection against infection. A well-suited methodology to study complex functional phenotypes of antiviral T cells is the combined staining of intracellular cytokines and phenotypic marker expression using polychromatic flow cytometry. In this study we analyzed the effect of an overnight resting period at 37°C on the quantity and functionality of HIV-1, EBV, CMV, HBV and HCV specific CD4 and CD8 T-cell responses in a cohort of 21 individuals. We quantified total antigen specific T cells by multimer staining and used 10-color intracellular cytokine staining (ICS) to determine IFNγ, TNFα, IL2 and MIP1β production. After an overnight resting significantly higher numbers of functionally active T cells were detectable by ICS for all tested antigen specificities, whereas the total number of antigen specific T cells determined by multimer staining remained unchanged. Overnight resting shifted the quality of T-cell responses towards polyfunctionality and increased antigen sensitivity of T cells. Our data suggest that the observed effect is mediated by T cells rather than by antigen presenting cells. We conclude that overnight resting of PBMC prior to ex vivo analysis of antiviral T-cell responses represents an efficient method to increase sensitivity of ICS-based methods and has a prominent impact on the functional phenotype of T cells.

Immune responses to cancer: are they potential biomarkers of prognosis?

Recent technical improvements in evaluations of immune cells in situ and immune monitoring of patients with cancer have provided a wealth of new data confirming that immune cells play a key role in human cancer progression. This, in turn, has revived the expectation that immune endpoints might serve as reliable biomarkers of outcome or response to therapy in cancer. The recent successes in linking the T-cell signature in human colorectal carcinoma (CRC) with prognosis have provided a strong motive for searching for additional immune biomarkers that could serve as intermediate endpoints of response to therapy and outcome in human cancers. A number of potentially promising immune biomarkers have emerged, but most remain to be validated. Among them, the B-cell signature, as exemplified by expression of the immunoglobulin G kappa chain (IGKC) in tumor-infiltrating lymphocytes (TIL), has been validated as a biomarker of response to adjuvant therapy and better survival in patients with breast carcinoma and several other types of human solid tumors. Additional immune endpoints are being currently tested as potentially promising biomarkers in cancer. In view of currently growing use of immune cancer therapies, the search for immune biomarkers of prognosis are critically important for identifying patients who would benefit the most from adjuvant immunotherapy.

Quality control, analysis and secure sharing of Luminex® immunoassay data using the open source LabKey Server platform

BACKGROUND

Immunoassays that employ multiplexed bead arrays produce high information content per sample. Such assays are now frequently used to evaluate humoral responses in clinical trials. Integrated software is needed for the analysis, quality control, and secure sharing of the high volume of data produced by such multiplexed assays. Software that facilitates data exchange and provides flexibility to perform customized analyses (including multiple curve fits and visualizations of assay performance over time) could increase scientists' capacity to use these immunoassays to evaluate human clinical trials.

RESULTS

The HIV Vaccine Trials Network and the Statistical Center for HIV/AIDS Research and Prevention collaborated with LabKey Software to enhance the open source LabKey Server platform to facilitate workflows for multiplexed bead assays. This system now supports the management, analysis, quality control, and secure sharing of data from multiplexed immunoassays that leverage Luminex xMAP® technology. These assays may be custom or kit-based. Newly added features enable labs to: (i) import run data from spreadsheets output by Bio-Plex Manager™ software; (ii) customize data processing, curve fits, and algorithms through scripts written in common languages, such as R; (iii) select script-defined calculation options through a graphical user interface; (iv) collect custom metadata for each titration, analyte, run and batch of runs; (v) calculate dose-response curves for titrations; (vi) interpolate unknown concentrations from curves for titrated standards; (vii) flag run data for exclusion from analysis; (viii) track quality control metrics across runs using Levey-Jennings plots; and (ix) automatically flag outliers based on expected values. Existing system features allow researchers to analyze, integrate, visualize, export and securely share their data, as well as to construct custom user interfaces and workflows.

CONCLUSIONS

Unlike other tools tailored for Luminex immunoassays, LabKey Server allows labs to customize their Luminex analyses using scripting while still presenting users with a single, graphical interface for processing and analyzing data. The LabKey Server system also stands out among Luminex tools for enabling smooth, secure transfer of data, quality control information, and analyses between collaborators. LabKey Server and its Luminex features are freely available as open source software at http://www.labkey.com under the Apache 2.0 license.

The development of standard samples with a defined number of antigen-specific T cells to harmonize T cell assays: a proof-of-principle study

The validation of assays that quantify antigen-specific T cell responses is critically dependent on cell samples that contain clearly defined measurable numbers of antigen-specific T cells. An important requirement is that such cell samples are handled and analyzed in a comparable fashion to peripheral blood mononuclear cells (PBMC). We performed a proof-of-principle study to show that retrovirally TCR-transduced T cells spiked at defined numbers in autologous PBMC can be used as standard samples for HLA/peptide multimer staining. NY-ESO-1157-165-specific, TCR-transduced CD8+ T cell batches were successfully generated from PBMC of several HLA-A*0201 healthy donors, purified by magnetic cell sorting on the basis of HLA tetramer (TM) staining and expanded with specific antigen in vitro. When subsequently spiked into autologous PBMC, the detection of these CD3+CD8+TM+ T cells was highly accurate with a mean accuracy of 91.6 %. The standard cells can be preserved for a substantial period of time in liquid nitrogen. Furthermore, TM staining of fresh and cryopreserved standard samples diluted at decreasing concentrations into autologous cryopreserved unspiked PBMC revealed that the spiked CD3+CD8+TM+ T cells could be accurately detected at all dilutions in a linear fashion with a goodness-of-fit of over 0.99 at a frequency of at least 0.02 % among the CD3+CD8+ T cell population. Notably, the CD3+CD8+TM+ cells of the standard samples were located exactly within the gates used to analyze patient samples and displayed a similar scatter pattern. The performance of the cryopreserved standard samples in the hands of 5 external investigators was good with an inter-laboratory variation of 32.9 % and the doubtless identification of one outlier.

Addition of interferon-α to the p53-SLP® vaccine results in increased production of interferon-γ in vaccinated colorectal cancer patients: a phase I/II clinical trial

We previously established safety and immunogenicity of a p53 synthetic long peptides (p53-SLP®) vaccine. In the current trial, we investigated whether combination of interferon-alpha (IFN-α) with p53-SLP® is both safe and able to improve the induced p53-specific IFN-γ response. Eleven colorectal cancer patients successfully treated for metastatic disease were enrolled in this study. Of these, nine patients completed follow-up after two injections with p53-SLP® together with IFN-α. Safety and p53-specific immune responses were determined before and after vaccination. Furthermore, cryopreserved PBMCs were compared head-to-head to cryopreserved PBMCs obtained in our previous trial with p53-SLP® only. Toxicity of p53-SLP® vaccination in combination with IFN-α was limited to Grade 1 or 2, with predominantly small ongoing swellings at the vaccination site. All patients harbored p53-specific T cells after vaccination and most patients showed p53-specific antibodies. Compared to the previous trial, addition of IFN-α significantly improved the frequency of p53-specific T cells in IFN-γ ELISPOT. Moreover, in this trial, p53-specific T cells were detectable in blood samples of all patients in a direct ex vivo multiparameter flowcytometric assay, opposed to only 2 of 10 patients vaccinated with p53-SLP® only. Finally, patients in this trial displayed a broader p53-specific immunoglobulin-G response, indicating an overall better p53-specific T-helper response. Our study shows that p53-SLP® vaccination combined with IFN-α injection is safe and capable of inducing p53-specific immunity. When compared to a similar trial with p53-SLP® vaccination alone the combination was found to induce significantly more IFN-γ producing p53-specific T cells.

A placebo-controlled randomized HPV16 synthetic long-peptide vaccination study in women with high-grade cervical squamous intraepithelial lesions

The aim of this study was to investigate the capacity of an HPV16 E6/E7 synthetic overlapping long-peptide vaccine to stimulate the HPV16-specific T-cell response, to enhance the infiltration of HPV16-specific type 1 T cells into the lesions of patients with HPV16+ high-grade cervical squamous intraepithelial lesion (HSIL) and HPV clearance. This was a placebo-controlled randomized phase II study in patients with HPV16-positive HSIL. HPV16-specific T-cell responses were determined pre- and post-vaccination by ELISPOT, proliferation assay and cytokine assays in PBMC and HSIL-infiltrating lymphocytes, and delayed-type hypersensitivity skin tests. Motivational problems of this patient group to postpone treatment of their premalignant lesions affected the inclusion rates and caused the study to stop prematurely. Of the accrued patients, 4 received a placebo and 5 received 1-2 vaccinations. Side effects mainly were flu-like symptoms and injection site reactions. A strong HPV-specific IFNγ-associated T-cell response was detected by ELISPOT in all vaccinated patients. The outcome of the skin tests correlated well with the ELISPOT analysis. The cytokine profile associated with HPV16-specific proliferation varied from robust type 1 to dominant type 2 responses. No conclusions could be drawn on vaccine-enhanced T-cell infiltration of the lesion, and there was no HPV clearance at the time of LEEP excision. Thus, vaccination of HSIL patients results in increased HPV16-specific T-cell immunity. Further development of this type of treatment relies on the ability to motivate patients and in the reduction in the side effects.

Harmonization of the intracellular cytokine staining assay

Active immunotherapy for cancer is an accepted treatment modality aiming to reinforce the T-cell response to cancer. T-cell reactivity is measured by various assays and used to guide the clinical development of immunotherapeutics. However, data obtained across different institutions may vary substantially making comparative conclusions difficult. The Cancer Immunotherapy Immunoguiding Program organizes proficiency panels to identify key parameters influencing the outcome of commonly used T-cell assays followed by harmonization. Our successes with IFNγ-ELISPOT and peptide HLA multimer analysis have led to the current study on intracellular cytokine staining (ICS). We report the results of three successive panels evaluating this assay. At the beginning, 3 out of 9 participants (33 %) were able to detect >6 out of 8 known virus-specific T-cell responses in peripheral blood of healthy individuals. This increased to 50 % of the laboratories in the second phase. The reported percentages of cytokine-producing T cells by the different laboratories were highly variable with coefficients of variation well over 60 %. Variability could partially be explained by protocol-related differences in background cytokine production leading to sub-optimal signal-to-noise ratios. The large number of protocol variables prohibited identification of prime guidelines to harmonize the assays. In addition, the gating strategy used to identify reactive T cells had a major impact on assay outcome. Subsequent harmonization of the gating strategy considerably reduced the variability within the group of participants. In conclusion, we propose that first basic guidelines should be applied for gating in ICS experiments before harmonizing assay protocol variables.

DNA fusion-gene vaccination in patients with prostate cancer induces high-frequency CD8(+) T-cell responses and increases PSA doubling time

We report on the immunogenicity and clinical effects in a phase I/II dose escalation trial of a DNA fusion vaccine in patients with prostate cancer. The vaccine encodes a domain (DOM) from fragment C of tetanus toxin linked to an HLA-A2-binding epitope from prostate-specific membrane antigen (PSMA), PSMA_27–35. We evaluated the effect of intramuscular vaccination without or with electroporation (EP) on vaccine potency. Thirty-two HLA-A2⁺ patients were vaccinated and monitored for immune and clinical responses for a follow-up period of 72 weeks. At week 24, cross-over to the immunologically more effective delivery modality was permitted; this was shown to be with EP based on early antibody data, and subsequently, 13/15 patients crossed to the +EP arm. Thirty-two HLA-A2⁻ control patients were assessed for time to next treatment and overall survival. Vaccination was safe and well tolerated. The vaccine induced DOM-specific CD4⁺ and PSMA₂₇-specific CD8⁺ T cells, which were detectable at significant levels above baseline at the end of the study (p = 0.0223 and p = 0.00248, respectively). Of 30 patients, 29 had a measurable CD4⁺ T-cell response and PSMA₂₇-specific CD8⁺ T cells were detected in 16/30 patients, with or without EP. At week 24, before cross-over, both delivery methods led to increased CD4⁺ and CD8⁺ vaccine-specific T cells with a trend to a greater effect with EP. PSA doubling time increased significantly from 11.97 months pre-treatment to 16.82 months over the 72-week follow-up (p = 0.0417), with no clear differential effect of EP. The high frequency of immunological responses to DOM-PSMA₂₇ vaccination and the clinical effects are sufficiently promising to warrant further, randomized testing.

Harmonization of immune biomarker assays for clinical studies

Assays that measure a patient's immune response play an increasingly important role in the development of immunotherapies. The inherent complexity of these assays and independent protocol development between laboratories result in high data variability and poor reproducibility. Quality control through harmonization--based on integration of laboratory-specific protocols with standard operating procedures and assay performance benchmarks--is one way to overcome these limitations. Harmonization guidelines can be widely implemented to address assay performance variables. This process enables objective interpretation and comparison of data across clinical trial sites and also facilitates the identification of relevant immune biomarkers, guiding the development of new therapies.

The immuno-oncology framework: Enabling a new era of cancer therapy

Developers of cancer immunotherapy have struggled for decades to achieve clinical success in using the patient's immune system to treat cancer. In the absence of a defined development paradigm for immunotherapies, conventional criteria established for chemotherapy were applied to these agents. This article summarizes the recent lessons for development of agents in the immunotherapy space, describes the systematic creation of a new clinical development paradigm for cancer immunotherapies and integrates this paradigm with the emerging methodological framework for a new clinical sub-specialty of immuno-oncology, which was driven by the collaborative work between the Cancer Immunotherapy Consortium (CIC) of the Cancer Research Institute in the US and the Association for Cancer Immunotherapy (CIMT) in Europe. This new framework provides a better defined development path and a foundation for more reproducible success of future therapies.

Humoral anti-KLH responses in cancer patients treated with dendritic cell-based immunotherapy are dictated by different vaccination parameters

Purpose

Keyhole limpet hemocyanin (KLH) attracts biomedical interest because of its remarkable immunostimulatory properties. Currently, KLH is used as vaccine adjuvant, carrier protein for haptens and as local treatment for bladder cancer. Since a quantitative human anti-KLH assay is lacking, it has not been possible to monitor the dynamics of KLH-specific antibody (Ab) responses after in vivo KLH exposure. We designed a quantitative assay to measure KLH-specific Abs in humans and retrospectively studied the relation between vaccination parameters and the vaccine-induced anti-KLH Ab responses.

Experimental design

Anti-KLH Abs were purified from pooled serum of melanoma patients who have responded to KLH as a vaccine adjuvant. Standard isotype-specific calibration curves were generated to measure KLH-specific Ab responses in individual serum samples using ELISA.

Results

KLH-specific IgM, IgA, IgG and all IgG-subclasses were accurately measured at concentrations as low as 20 μg/ml. The intra- and inter-assay coefficients of variation of this ELISA were below 6.7 and 9.9 %, respectively. Analyses of 128 patients demonstrated that mature DC induced higher levels of KLH-specific IgG compared to immature DC, prior infusion with anti-CD25 abolished IgG and IgM production and patients with locoregional disease developed more robust IgG responses than advanced metastatic melanoma patients.

Conclusions

We present the first quantitative assay to measure KLH-specific Abs in human serum, which now enables monitoring both the dynamics and absolute concentrations of humoral immune responses in individuals exposed to KLH. This assay may provide a valuable biomarker for the immunogenicity and clinical effectiveness of KLH-containing vaccines and therapies.

Electronic supplementary material

The online version of this article (doi:10.1007/s00262-012-1263-z) contains supplementary material, which is available to authorized users.

The simultaneous ex vivo detection of low-frequency antigen-specific CD4+ and CD8+ T-cell responses using overlapping peptide pools

The ability to measure antigen-specific T cells at the single-cell level by intracellular cytokine staining (ICS) is a promising immunomonitoring tool and is extensively applied in the evaluation of immunotherapy of cancer. The protocols used to detect antigen-specific CD8+ T-cell responses generally work for the detection of antigen-specific T cells in samples that have undergone at least one round of in vitro pre-stimulation. Application of a common protocol but now using long peptides as antigens was not suitable to simultaneously detect antigen-specific CD8+ and CD4+ T cells directly ex vivo in cryopreserved samples. CD8 T-cell reactivity to monocytes pulsed with long peptides as antigens ranged between 5 and 25 % of that observed against monocytes pulsed with a direct HLA class I fitting minimal CTL peptide epitope. Therefore, we adapted our ICS protocol and show that the use of tenfold higher concentration of long peptides to load APC, the use of IFN-α and poly(I:C) to promote antigen processing and improve T-cell stimulation, does allow for the ex vivo detection of low-frequency antigen-specific CD8+ and CD4+ T cells in an HLA-independent setting. While most of the improvements were related to increasing the ability to measure CD8+ T-cell reactivity following stimulation with long peptides to at least 50 % of the response detected when using a minimal peptide epitope, the final analysis of blood samples from vaccinated patients successfully showed that the adapted ICS protocol also increases the ability to ex vivo detect low-frequency p53-specific CD4+ T-cell responses in cryopreserved PBMC samples.

Report from the second cytomegalovirus and immunosenescence workshop

The Second International Workshop on CMV & Immunosenescence was held in Cambridge, UK, 2-4^th December, 2010. The presentations covered four separate sessions: cytomegalovirus and T cell phenotypes; T cell memory frequency, inflation and immunosenescence; cytomegalovirus in aging, mortality and disease states; and the immunobiology of cytomegalovirus-specific T cells and effects of the virus on vaccination. This commentary summarizes the major findings of these presentations and references subsequently published work from the presenter laboratory where appropriate and draws together major themes that were subsequently discussed along with new areas of interest that were highlighted by this discussion.

Evaluation of current cancer immunotherapy: hemato-oncology

Hematologic malignancies were the first diseases in clinical oncology for which the potential of harnessing the immune system as targeted therapy was unequivocally demonstrated. Unfortunately, the use of this highly efficacious modality has been limited to only a subset of patients and diseases because of immune-mediated toxicities resulting from incomplete specificity, and disease-specific determinants of sensitivity versus resistance to immune effector mechanisms. Recent studies, however, have begun to elucidate the molecular basis of the observed clinical effects allowing the rational development of next generation of immunotherapeutic combinations. We discuss here cancer antigen targets in hematologic malignancies and the specific approaches to induce immunity being pursued, the importance of modulating the host immunoregulatory environment, and the special features of immunological monitoring in clinical investigation. The hematologic malignancies represent an ideal setting for the development of immunotherapy due to logistical, clinical monitoring, and disease biology factors and may represent an exemplar for immune-based treatment in other cancer types.

A critical assessment for the value of markers to gate-out undesired events in HLA-peptide multimer staining protocols

BACKGROUND

The introduction of antibody markers to identify undesired cell populations in flow-cytometry based assays, so called DUMP channel markers, has become a practice in an increasing number of labs performing HLA-peptide multimer assays. However, the impact of the introduction of a DUMP channel in multimer assays has so far not been systematically investigated across a broad variety of protocols.

METHODS

The Cancer Research Institute's Cancer Immunotherapy Consortium (CRI-CIC) conducted a multimer proficiency panel with a specific focus on the impact of DUMP channel use. The panel design allowed individual laboratories to use their own protocol for thawing, staining, gating, and data analysis. Each experiment was performed twice and in parallel, with and without the application of a dump channel strategy.

RESULTS

The introduction of a DUMP channel is an effective measure to reduce the amount of non-specific MULTIMER binding to T cells. Beneficial effects for the use of a DUMP channel were observed across a wide range of individual laboratories and for all tested donor-antigen combinations. In 48% of experiments we observed a reduction of the background MULTIMER-binding. In this subgroup of experiments the median background reduction observed after introduction of a DUMP channel was 0.053%.

CONCLUSIONS

We conclude that appropriate use of a DUMP channel can significantly reduce background staining across a large fraction of protocols and improve the ability to accurately detect and quantify the frequency of antigen-specific T cells by multimer reagents. Thus, use of a DUMP channel may become crucial for detecting low frequency antigen-specific immune responses. Further recommendations on assay performance and data presentation guidelines for publication of MULTIMER experimental data are provided.

Meeting Report from the Second "Minimum Information for Biological and Biomedical Investigations" (MIBBI) workshop

This report summarizes the proceedings of the second workshop of the 'Minimum Information for Biological and Biomedical Investigations' (MIBBI) consortium held on Dec 1-2, 2010 in Rüdesheim, Germany through the sponsorship of the Beilstein-Institute. MIBBI is an umbrella organization uniting communities developing Minimum Information (MI) checklists to standardize the description of data sets, the workflows by which they were generated and the scientific context for the work. This workshop brought together representatives of more than twenty communities to present the status of their MI checklists and plans for future development. Shared challenges and solutions were identified and the role of MIBBI in MI checklist development was discussed. The meeting featured some thirty presentations, wide-ranging discussions and breakout groups. The top outcomes of the two-day workshop as defined by the participants were: 1) the chance to share best practices and to identify areas of synergy; 2) defining a series of tasks for updating the MIBBI Portal; 3) reemphasizing the need to maintain independent MI checklists for various communities while leveraging common terms and workflow elements contained in multiple checklists; and 4) revision of the concept of the MIBBI Foundry to focus on the creation of a core set of MIBBI modules intended for reuse by individual MI checklist projects while maintaining the integrity of each MI project. Further information about MIBBI and its range of activities can be found at http://mibbi.org/.