Combinatorial multimer staining and spectral flow cytometry facilitate quantification and characterization of polysaccharide-specific B cell immunity

Bacterial capsular polysaccharides are important vaccine immunogens. However, the study of polysaccharide-specific immune responses has been hindered by technical restrictions. Here, we developed and validated a high-throughput method to analyse antigen-specific B cells using combinatorial staining with fluorescently-labelled capsular polysaccharide multimers. Concurrent staining of 25 cellular markers further enables the in-depth characterization of polysaccharide-specific cells. We used this assay to simultaneously analyse 14 Streptococcus pneumoniae or 5 Streptococcus agalactiae serotype-specific B cell populations. The phenotype of polysaccharide-specific B cells was associated with serotype specificity, vaccination history and donor population. For example, we observed a link between non-class switched (IgM+) memory B cells and vaccine-inefficient S. pneumoniae serotypes 1 and 3. Moreover, B cells had increased activation in donors from South Africa, which has high-incidence of S. agalactiae invasive disease, compared to Dutch donors. This assay allows for the characterization of heterogeneity in B cell immunity that may underlie immunization efficacy

Maturation of monocyte-derived dendritic cells with Toll-like receptor 3 and 7/8 ligands combined with prostaglandin E2 results in high interleukin-12 production and cell migration

Dendritic cells (DC) are professional antigen-presenting cells of the immune system that play a key role in regulating T cell-based immunity. In vivo, the capacity of DC to activate T cells depends on their ability to migrate to the T cell areas of lymph nodes as well as on their maturation state. Depending on their cytokine-secreting profile, DC are able to skew the immune response in a specific direction. In particular, IL-12p70 producing DC drive T cells towards a T helper 1 type response. A serious disadvantage of current clinical grade ex vivo generated monocyte-derived DC is the poor IL-12p70 production. We have investigated the effects of Toll-like receptor (TLR)-mediated maturation on ex vivo generated human monocyte-derived DC. We demonstrate that in contrast to cytokine-matured DC, DC matured with poly(I:C) (TLR3 ligand) and/or R848 (TLR7/8 ligand) are able to produce vast amounts of IL-12p70, but exhibit a reduced migratory capacity. The addition of prostaglandin E2 (PGE2) improved the migratory capacity of TLR-ligand matured DC while maintaining their IL-12p70 production upon T cell encounter. We propose a novel clinical grade maturation protocol in which TLR ligands poly(I:C) and R848 are combined with PGE2 to generate DC with both high migratory capacity and IL-12p70 production upon T cell encounter

Stable long-term cultures of self-renewing B cells and their applications

Monoclonal antibodies are essential therapeutics and diagnostics in a large number of diseases. Moreover, they are essential tools in all sectors of life sciences. Although the great majority of monoclonal antibodies currently in use are of mouse origin, the use of human B cells to generate monoclonal antibodies is increasing as new techniques to tap the human B cell repertoire are rapidly emerging. Cloned lines of immortalized human B cells are ideal sources of monoclonal antibodies. In this review, we summarize our studies to the regulation of the replicative life span, differentiation, and maturation of B cells that led to the development of a platform that uses immortalization of human B cells by in vitro genetic modification for antibody development. We describe a number of human antibodies that were isolated using this platform and the application of the technique in other species. We also discuss the use of immortalized B cells as antigen-presenting cells for the discovery of tumor neoantigen

Genetic manipulation of B cells for the isolation of rare therapeutic antibodies from the human repertoire

Antibody based therapies are increasingly applied to prevent and treat human disease. While the majority of antibodies currently on the market are chimeric or humanized antibodies from rodents, the focus has now shifted to the isolation and development of fully human antibodies. By retroviral transduction of B cell lymphoma-6 (BCL-6), which prevents terminal differentiation of B cells and, the anti-apoptotic gene B-cell lymphoma-extra large (Bcl-xL) into primary human B cells we efficiently immortalize antibody-producing B cells allowing the isolation of therapeutic antibodies. Selection of antigen-specific B cell clones was greatly facilitated because the transduced B cells retain surface immunoglobulin expression and secrete immunoglobulin into the culture supernatant. Surface immunoglobulin expression can be utilized to stain and isolate antigen specific B cell clones with labeled antigen. Immunoglobulins secreted in culture supernatant can directly be tested in functional assays to identify unique B cell clones. Here we describe the key features of our Bcl-6/Bcl-xL culture platform (AIMSelect

IgG subclasses of anti-FVIII antibodies during immune tolerance induction in patients with hemophilia A

The eradication of inhibitory antibodies in patients with haemophilia A can be accomplished by frequent administration of high or intermediate doses of factor VIII (FVIII), so-called immune tolerance induction (ITI). This study monitored the distribution of IgG subclasses of anti-FVIII antibodies during ITI. FVIII-specific antibodies of subclass IgG1 were detected in all inhibitor patients tested, anti-FVIII IgG4 in 16, IgG2 in 10 and IgG3 in one of 20 patients analysed. Levels of anti-FVIII IgG1 and IgG4 correlated well with inhibitor titres as measured by Bethesda assay. In low-titre inhibitor patients, anti-FVIII antibodies consisted primarily of subclass IgG1 whereas, anti-FVIII antibodies of subclass IgG4 were more prominent in patients with high titre inhibitors who needed prolonged treatment or who failed ITI. Longitudinal analysis of 14 patients undergoing ITI revealed that the relative contribution of IgG subclasses was constant for most of the patients analysed. In two patients, the relative contribution of IgG4 increased during ITI. Overall, our findings document the distribution and dynamics of anti-FVIII IgG subclasses during ITI. Future studies will need to address whether monitoring the relative contribution of anti-FVIII subclasses IgG1 and IgG4 may be useful for the identification of patients who are at risk of failing IT

Gene-expression patterns in whole blood identify subjects at risk for recurrent tuberculosis.

BACKGROUND: The majority of patients with tuberculosis who comply with appropriate treatment are cured. However, approximately 5% subsequently have a repeat disease episode, usually within 2 years of successful combination therapy. Presently, there is no way of predicting which patients will experience a relapse. METHODS: We identified 10 subjects who had previously experienced recurrent tuberculosis and carefully matched them to cured subjects who had had only 1 episode of tuberculosis, to patients with active tuberculosis, and to latently infected healthy subjects. We compared their ex vivo whole-blood gene-expression profiles by use of DNA array technology and confirmed the results by use of quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR). RESULTS: The 4 clinical tuberculosis groups exhibited distinct patterns of gene expression. The gene-transcript profiles of the patients with recurrent tuberculosis were more similar to those of the patients with active tuberculosis than to those of the cured or latently infected subjects. Discriminant analysis of a training data set showed that 9 genes were sufficient to classify the subjects. We confirmed that measurement of the expression of these genes by qRT-PCR can accurately discriminate between subjects in a test set of samples. CONCLUSIONS: A simple test based on gene-expression patterns may be used as a biomarker of cure while identifying patients who are at risk for relapse. This would facilitate the introduction of new tuberculosis drugs

Tuberculosis Patients Blood Gene Expression Through Treatment (cured and end-of-treatment patients)

Background Accurate assessment of treatment efficacy would facilitate clinical trials of new anti-tuberculosis drugs. TB patients exhibit altered peripheral immunity which reverts during successful treatment. We hypothesised that these changes could be observed in whole blood transcriptome profiles. Methods Ex vivo blood samples from 27 pulmonary TB patients were assayed at diagnosis and during conventional treatment. RNA was processed and hybridised to Affymetrix GeneChips, to determine expression of over 47,000 transcripts. Findings There were significant changes in expression of over 4,000 genes during treatment. Rapid, large scale changes were detected, with down-regulated expression of ~1,000 genes within the first week, including inflammatory markers such as the complement components C1q and C2. This was followed by slower changes in expression of different networks of genes, including a later increase in expression of B cell markers, transcription factors and signalling molecules. Interpretation The expression of many genes is drastically altered during TB disease, with components of the humoral immune response being markedly affected. The treatment-induced restoration reflects the simultaneous suppression and activation of different immune responses in TB. The rapid initial down-regulation of expression of inflammatory mediators coincides with rapid killing of actively dividing bacilli, whereas slower delayed changes occur as drugs act on dormant bacilli and as lung pathology resolves. Measurement of biosignatures during clinical trials of new drugs could be useful predictors of rapid bactericidal or sterilizing drug activity. Ex vivo blood samples analysed during TB treatment. These samples are from 9 successfully cured patients at diagnosis and end-of-treatment at 26 weeks

Tuberculosis Patients Blood Gene Expression Through Treatment

Accurate assessment of treatment efficacy would facilitate clinical trials of new anti-tuberculosis drugs. TB patients exhibit altered peripheral immunity which reverts during successful treatment. We hypothesised that these changes could be observed in whole blood transcriptome profiles. Methods Ex vivo blood samples from 27 pulmonary TB patients were assayed at diagnosis and during conventional treatment. RNA was processed and hybridised to Affymetrix GeneChips, to determine expression of over 47,000 transcripts. Findings There were significant changes in expression of over 4,000 genes during treatment. Rapid, large scale changes were detected, with down-regulated expression of ~1,000 genes within the first week, including inflammatory markers such as the complement components C1q and C2. This was followed by slower changes in expression of different networks of genes, including a later increase in expression of B cell markers, transcription factors and signalling molecules. Interpretation The expression of many genes is drastically altered during TB disease, with components of the humoral immune response being markedly affected. The treatment-induced restoration reflects the simultaneous suppression and activation of different immune responses in TB. The rapid initial down-regulation of expression of inflammatory mediators coincides with rapid killing of actively dividing bacilli, whereas slower delayed changes occur as drugs act on dormant bacilli and as lung pathology resolves. Measurement of biosignatures during clinical trials of new drugs could be useful predictors of rapid bactericidal or sterilizing drug activity. Ex vivo blood samples analysed for 27 first episode pulmonary TB patients, at diagnosis and after 1, 2, 4 and 26 weeks of treatment