Presence Of B-cells Research Articles

Rational design of a multi-epitope vaccine against heartland virus (HRTV) using immune-informatics, molecular docking and dynamics approaches

Heartland virus (HRTV) is a single-stranded negative-sense RNA virus that infects human beings. Because there are no antiviral medications available to treat HRTV infection, supportive care management is used in cases of severe disease. Therefore, it has spurred research into developing a multi-epitope vaccine capable of providing effective protection against HRTV infection. A multi-epitope vaccine was created using a combination of immuno-informatics, molecular docking and molecular dynamics simulation in this investigation. The HRTV proteome was utilized to predict B-cell, T-cell (HTL and CTL), and IFN-epitopes. Following prediction, highly antigenic, non-allergenic and immunogenic epitopes were chosen, including 6 CTL, 8 HTL, and 5 LBL epitopes that were connected to the final peptide by AAY, GPGPG, and KK linkers, respectively. An adjuvant was introduced to the vaccine's N-terminal through the EAAAK linker to increase its immunogenicity. Following the inclusion of linkers and adjuvant, the final construct has 359 amino acids. The presence of B-cell and IFN-γ-epitopes validates the construct's acquired humoral and cell-mediated immune responses. To ensure the vaccine's safety and immunogenicity profile, its allergenicity, antigenicity, and various physicochemical characteristics were assessed. Docking was used to assess the binding affinity and molecular interaction between the vaccination and TLR-3. In silico cloning was used to confirm the construct's validity and expression efficiency. The results of these computer assays demonstrated that the designed vaccine is highly promising in terms of developing protective immunity against HRTV; nevertheless, additional in vivo and in vitro investigations are required to validate its true immune-protective efficiency.

P052 Mucosal IgG-like naive B-cell expansion and maturation contribute to ulcerative colitis pathogenesis

Abstract Background A higher abundance of colonic naive B-cells and IgG plasma cells is implicated in the pathogenesis of ulcerative colitis (UC) during active inflammatory episodes. However, B-cell inhibition by targeting CD20 was found to be ineffective in achieving remission in UC patients indicating that the causal role of the B-cell expansion in UC is not well understood. In this study, we performed single cell RNA-sequencing (scRNA-seq) on mucosal tissue where we interrogated the B-cells in inflamed and non-inflamed UC colon biopsies. We subsequently explored the pathogenic role of B-cells in colitis mouse models. Methods We collected biopsies from the colon of 5 UC patients with active inflammation and 5 UC patients showing no inflamed mucosa. Three mucosal biopsies were collected from the same colon location for each patient and processed for scRNA-seq. We acquired usable transcriptomes of 21.475 cells. In a T-cell transfer colitis mice model, we evaluated the effects of the co-transfer of naive B-cells. Both CD4+ T and naive B-cells were transferred into SCID mice through intraperitoneal injection in ratios of 2:1, 1:1 and 1:2 (T:B ratio). The colitis course was followed for 35 days. Results Differential abundance analysis relative to all immune cells confirmed a higher abundance of naive B-cells (p= 0.03) and IgG plasma B-cells (p= 0.002) in inflamed relative to non-inflamed UC patient tissue, whereas no differences in abundance of transitional B-cells and memory B-cells were found. Pseudo-time analysis indicated a higher rate of maturation in the naive B-cells in inflamed tissue. This was evidenced by higher expression of IGHG1 (p= 0.025) and IGHG3 (p< 0.001) in naive B-cells in inflamed tissue. In a T-cell transfer model, we co-transferred naive B-cells to the CD4+ T-cell pool into SCID mice in various ratios (2:1, 1:1 and 1:2 T to B-cells respectively) and T-cell only control. Significant increase in disease severity was observed in a 1:2 T:B ratio based on body weight loss, increase of colon density, mouse colitis histology index and histological changes by disrupted mucosa. This observation was associated to significant elevated IgG concentration in serum and colon and B-cell presence in colon through immunohistochemistry. Conclusion We observed significantly higher abundance of naive B-cells and IgG plasma cells in inflamed relative to non-inflamed UC colon tissue, where naive B-cells were shown to be more mature and IgG-like in inflamed condition. Notably, transferring increased ratio of naive B-cells resulted in elevated disease severity in a colitis model, demonstrating its pathogenic role. Our findings suggest that specific targeting of the IgG-like naive B-cell may be beneficial for UC patients.

137 Molecular investigation of secondary syphilis in the skin characterizes the nature of the B-cell promoting inflammatory environment

Syphilis is a sexually transmitted disease with prominent cutaneous manifestations. A frequent histologic feature of syphilis is the presence of B-cells and plasma cells, which are infrequently observed in other acute inflammatory diseases of the skin. To determine the regulation of this unique inflammatory environment in syphilis, we performed bulk RNA-seq on formalin-fixed, paraffin-embedded biopsies obtained from 9 patients with secondary syphilis and 8 healthy controls. Using a threshold of a twofold increase or decrease and a false discovery rate (FDR) of 0.05, we found 917 genes to be differentially expressed in secondary syphilis in skin.

The Role of B Cells in Head and Neck Cancer.

Simple SummaryHost immunity has established its role in deciding the course of cancer evolution. As cellular and molecular components in the tumor microenvironment peripherally appear to be at a constant interplay, favoring either tumor control or progression, it is vital to decrypt the immunity elements, which demonstrate the potential to be harnessed towards cancer elimination. Head and neck cancer has been characterized as densely immune infiltrated but at the same time a highly immunosuppressive malignancy due to a negative equilibrium between active and dysfunctional immune cell populations. B-cells constitute the cornerstone of humoral immunity; however, their role in cancer has been vastly overlooked in comparison to other immune subtypes and reports from multiple studies fail to show agreement on their prognostic impact. This review focuses on the role of B-cells on head and neck cancer with the aim to highlight their effect on anti-cancer immunity, as well as their possible impact on immunotherapy outcomes.Head and neck cancer comprises a heterogenous, highly immune infiltrated malignancy, defined by a predominantly immunosuppressive tumor microenvironment (TME). In recent years, PD-1/PD-L1 immune checkpoint inhibitors have become the standard of care treatment, either as monotherapy or in combination with chemotherapy agents, thus revolutionizing the therapeutic landscape of recurrent/metastatic disease. As a result, preclinical research is increasingly focusing on TME composition and pathophysiology, aiming to comprehensively characterize the specific elements and interactions affecting anti-tumor immunity, as well as to unveil novel predictive biomarkers of immunotherapy outcomes. While T lymphocytic populations have been vastly explored regarding their effect on cancer development, B-cells constitute a far less investigated, yet possibly equally important, aspect of cancer immunity. B-cell presence, either as single cells or as part of tertiary lymphoid structures within the TME, has been associated with several anti-tumor defense mechanisms, such as antigen presentation, antibody production and participation in antibody-dependent cellular cytotoxicity, and has demonstrated prognostic significance for multiple types of malignancies. However, immunoregulatory B-cell phenotypes have also been identified both peripherally and within malignant tissue, bearing inhibitory effects on numerous immune response processes. Consequently, B-cells and their subsets demonstrate the potential to become valuable cancer biomarkers and acquire a leading role in future therapeutic strategies.

Direct contact between Plasmodium falciparum and human B-cells in a novel co-culture increases parasite growth and affects B-cell growth

BackgroundPlasmodium falciparum parasites cause malaria and co-exist in humans together with B-cells for long periods of time. Immunity is only achieved after repeated exposure. There has been a lack of methods to mimic the in vivo co-occurrence, where cells and parasites can be grown together for many days, and it has been difficult with long time in vitro studies.Methods and resultsA new method for growing P. falciparum in 5% CO2 with a specially formulated culture medium is described. This knowledge was used to establish the co-culture of live P. falciparum together with human B-cells in vitro for 10 days. The presence of B-cells clearly enhanced parasite growth, but less so when Transwell inserts were used (not allowing passage of cells or merozoites), showing that direct contact is advantageous. B-cells also proliferated more in presence of parasites. Symbiotic parasitic growth was verified using CESS cell-line and it showed similar results, indicating that B-cells are indeed the cells responsible for the effect. In malaria endemic areas, people often have increased levels of atypical memory B-cells in the blood, and in this assay it was demonstrated that when parasites were present there was an increase in the proportion of CD19 + CD20 + CD27 − FCRL4 + B-cells, and a contraction of classical memory B-cells. This effect was most clearly seen when direct contact between B-cells and parasites was allowed.ConclusionsThese results demonstrate that P. falciparum and B-cells undoubtedly can affect each other when allowed to multiply together, which is valuable information for future vaccine studies.

Absence of B Cells in Brainstem and White Matter Lesions Associates With Less Severe Disease and Absence of Oligoclonal Bands in MS

ObjectiveTo determine whether B-cell presence in brainstem and white matter (WM) lesions is associated with poorer pathological and clinical characteristics in advanced MS autopsy cases.MethodsAutopsy tissue of 140 MS and 24 control cases and biopsy tissue of 24 patients with MS were examined for CD20+ B cells and CD138+ plasma cells. The presence of these cells was compared with pathological and clinical characteristics. In corresponding CSF and plasma, immunoglobulin (Ig) G ratio and oligoclonal band (OCB) patterns were determined. In a clinical cohort of 73 patients, the presence of OCBs was determined during follow-up and compared to status at diagnosis.ResultsIn 34% of active and 71% of mixed active/inactive lesions, B cells were absent, which correlated with less pronounced meningeal B-cell infiltration (p < 0.0001). The absence of B cells and plasma cells in brainstem and WM lesions was associated with a longer disease duration (p = 0.001), less frequent secondary progressive MS compared with relapsing and primary progressive MS (p < 0.0001 and p = 0.046, respectively), a lower proportion of mixed active/inactive lesions (p = 0.01), and less often perivascular T-cell clustering (p < 0.0001). Moreover, a lower CSF IgG ratio (p = 0.006) and more frequent absence of OCBs (p < 0.0001) were noted. In a clinical cohort, numbers of patients without OCBs in CSF were increased at follow-up (27.4%).ConclusionsThe absence of B cells is associated with a favorable clinical and pathological profile. This finding may reflect extremes of a continuum of genetic or environmental constitution, but also a regression of WM humoral immunopathology in the natural course of advanced MS.

Abstract B46: Varying the inoculation site of mouse syngeneic tumors can result in aberrant inclusion of lymph node tissue at tumor harvest

Abstract In recent years, growing interest in immunotherapies for the treatment of cancer has led to increased reliance on murine syngeneic tumor models for preclinical study in immunocompetent animals. These studies typically examine changes in the quantities and phenotypes of tumor-infiltrating immune cells; thus, it is crucial to distinguish between these cells and extratumoral immune cells during tumor harvest. Here, we show that 4T1 breast tumors inoculated in mammary fat pads (MFP) numbers 4 or 9 (4/9) contained greater frequencies of B cells and naïve T cells than tumors inoculated in MFP numbers 5 or 10 (5/10). Immunohistochemical analysis for B-cell presence demonstrated that MFP 4/9 tumors encroached on, and often encapsulated, inguinal lymph nodes, such that lymph node tissue was unknowingly collected during tumor harvest. This prevented accurate enumeration and phenotyping of infiltrating immune cells by flow cytometry, as the majority of lymphocytes in the affected samples derived from lymph nodes, and had not infiltrated the tumor per se. We observed the same phenomenon in peritibial tumors using immunohistochemical analysis, which began to encapsulate popliteal lymph nodes at large tumor volumes (&amp;gt;1500 mm3). Our data highlight the importance of choosing an appropriate inoculation site for obtaining accurate and consistent results when evaluating immune cell infiltration in syngeneic tumor models. Citation Format: Renee Clift, Barbara Blouw, Susan Zimmerman, Sanna Rosengren, Curt Thompson, Benjamin Thompson. Varying the inoculation site of mouse syngeneic tumors can result in aberrant inclusion of lymph node tissue at tumor harvest [abstract]. In: Proceedings of the AACR Special Conference: Advances in Modeling Cancer in Mice: Technology, Biology, and Beyond; 2017 Sep 24-27; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(10 Suppl):Abstract nr B46.

Exploring dengue genome to construct a multi-epitope based subunit vaccine by utilizing immunoinformatics approach to battle against dengue infection

Dengue is considered as a major health issue which causes a number of deaths worldwide each year; tropical countries are majorly affected by dengue outbreaks. It is considered as life threatening issue because, since many decades not a single effective approach for treatment and prevention of dengue has been developed. Therefore, to find new preventive measure, we used immunoinformatics approaches to develop a multi-epitope based subunit vaccine for dengue which can generate various immune responses inside the host. Different B-cell, TC cell, and TH cell binding epitopes were predicted for structural and non-structural proteins of dengue virus. Final vaccine constructs consisting of TC and TH cell epitopes and an adjuvant (β-defensin) at N-terminal of the construct. Presence of B-cell and IFN-γ inducing epitopes confirms the humoral and cell mediated immune response developed by designed vaccine. Designed vaccine was not found allergic and was potentially antigenic in nature. Modeling of tertiary structure and the refined model was used for molecular docking with TLR-3 (immune receptor). Molecular docking and dynamics simulation confirms the microscopic interactions between ligand and receptor. In silico cloning approach was used to ensure the expression and translation efficiency of vaccine within an expression vector.

Immunoprotective potential of in silico predicted Acinetobacter baumannii outer membrane nuclease, NucAb

Acinetobacter baumannii is an emerging multi-drug resistant pathogen causing significant mortality in hospitalized ICU patients which demands developing new methods for prevention and treatment. A. baumannii 19606 proteome was analysed in silico through the online tool Vaxign for finding potential vaccine candidates. The selected nuclease (NucAb) was predicted to possess all the attributes of a promising vaccine candidate like outer membrane localization, high adhesin probability (0.53), one transmembrane helix only, non-homology to human proteins and presence of B-cell and T-cell epitopes binding with high affinity (percentile rank≤1) to HLA alleles prevalent at high frequency in North Indian populations. nucAb gene was highly prevalent (100%) among the clinical isolates (40/40) and conserved (>98%) among NCBI sequenced Acinetobacter strains. It was cloned in pET28a, purified and its immunoprotective potential was validated in murine pneumonia model. Immunization of BALB/c mice with recombinant NucAb (25μg) elicited high antibody titre (1–5×105) which reduced bacterial load by 5 log cycles in lungs of mice challenged with optimized lethal dose (108CFU). Lung histopathology revealed marked suppression of inflammation. Pro-inflammatory cytokines (TNF-α and IL-6) levels were reduced significantly and anti-inflammatory (IL-10) cytokine increased in lungs and serum leading to decreased severity and slow progression of disease. Though active immunization showed low survival rate (20%), passive immunization improved the survival (40%). This is the first study reporting an outer membrane nuclease as a vaccine candidate in Gram negative bacterium, A. baumannii through reverse vaccinology approach.

Characterization of the humoral immune response in a Lewis rat model of CIDP

Objective: Recently we have developed a reliable and reproducible preclinical chronic-EAN model in the Lewis rat that may prove useful for translational drug studies for CIDP. We have clearly shown that it is a T-cell mediated disease with an accumulation of IL-17 cells and macrophages in its late chronic phase. Since pathophysiological mechanisms involved in CIDP are believed to involve not only cellular but also humoral immunity, we therefore investigated the humoral response in our chronic-EAN model induced in the Lewis rat after injection of thiopalmitoylated P0(180–199) peptide in comparison to the classical acute EAN model induced with P0(180–199). Methods: We investigated by ELISA (at 18, 31, 43 and 57 dpi) in the sera of EAN and chronic-EAN rats the levels of antibodies directed against peptide P0(180–199), the inducing antigen. The reactivity of the antibodies obtained was tested on sciatic nerve by immunohistochemistry. To check the possibility of an epitope spreading at the late phase of the chronic disease, the reactivity of the sera at 60 dpi was tested by ELISA against different peptides described as neuritogenic: P0(56–71), P0(152–171), P0(180–199) and P2(57– 81). We also investigated the presence of B-cells in the sciatic nerve by immunohistochemistry using a mouse anti-rat CD45RA MnAb. Results: High levels of antibodies against P0(180–199) were found in chronic-EAN and EAN rats, but the antibody reactivity remained high in the chronic group for the duration of the disease, whereas it started to decline in the EAN group by day 57. At the late phase of the chronic disease (60 dpi) we found in the sera significant levels of antibodies against peptide P0(152–171) but this was not statistically different from the EAN group. No reactivity was detected against the other peptides. The rat polyclonal anti P0(180–199) antibodies labeled nicely the PNS myelin in a control sciatic nerve, highly comparable to the myelin labeling with the commercial anti-P0 MnAb. This indicates that the anti-P0(180–199) is able to recognize the corresponding peptide sequence when protein P0 is inserted in the myelin membrane. The presence of B cells was detected in the sciatic nerve of EAN rats and also of chronic-EAN rats but in greater number. Conclusion: We have indeed shown that there is a humoral response in our chronic model, but further studies are needed to clarify the roles of the antibodies and B-cells in the persistence of the chronicity of the disease.

AB0434 Relation of Subclinical Ultrasound Detected Synovitis and Peripheral B-Cell Counts in Rheumatoid Arthritis Patients Treated with Rituximab

BackgroundThe clinical response in patients with Rheumatoid Arthritis (RA) to rituximab (RTX) has been shown to be related with the presence of B-cells in the synovi. To date this has...

Differential gene expression in the proximal neck of human abdominal aortic aneurysm

ObjectiveAbdominal aortic aneurysm (AAA) represents a common cause of morbidity and mortality in elderly populations but the mechanisms involved in AAA formation remain incompletely understood. Previous human studies have focused on biopsies obtained from the center of the AAA however it is likely that pathological changes also occur in relatively normal appearing aorta away from the site of main dilatation. The aim of this study was to assess the gene expression profile of biopsies obtained from the neck of human AAAs. MethodsWe performed a microarray study of aortic neck specimens obtained from 14 patients with AAA and 8 control aortic specimens obtained from organ donors. Two-fold differentially expressed genes were identified with correction for multiple testing. Mechanisms represented by differentially expressed genes were identified using Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. Some of the differentially expressed genes were validated by quantitative real-time PCR (qPCR) and immunohistochemistry. ResultsWe identified 1047 differentially expressed genes in AAA necks. The KEGG analysis revealed marked upregulation of genes related to immunity. These pathways included cytokine–cytokine receptor interaction (P = 8.67*10−12), chemokine signaling pathway (P = 5.76*10−07), and antigen processing and presentation (P = 4.00*10−04). Examples of differentially expressed genes validated by qPCR included the T-cells marker CD44 (2.16-fold upregulated, P = 0.008) and the B-cells marker CD19 (3.14-fold upregulated, P = 0.029). The presence of B-cells in AAA necks was confirmed by immunohistochemistry. ConclusionsThe role of immunity in AAA is controversial. This study suggests that immune pathways are also upregulated within the undilated aorta proximal to an AAA.

The effects of in vivo B-cell depleting therapy on ex-vivo cytokine production

In renal transplantation, IL-17 production by T-cells might be dependent on the presence of B-cells. Therefore, the effect of in vivo B-cell depletion on ex-vivo IL-17 production was investigated.Twenty patients undergoing living-donor renal transplantation were recruited from a larger cohort of patients participating in a randomized, double-blind trial. All patients were allocated to a single intra-operative dose of either placebo or rituximab (375mg/m2) added to the standard immunosuppressive therapy. Blood was collected at baseline, at one day, and at one month after surgery. The healthy kidney donors also gave blood at baseline. Peripheral blood mononuclear cells were stimulated ex-vivo in different manners (heat killed Candida albicans yeast, heat killed Staphylococcus aureus, or αCD3αCD28 coated beads), to address the role of B-cells in ex-vivo cytokine responses. The concentration of monocyte- and T-cell-derived cytokines (IL-1β, IL-6, TNF-α, IFN-γ, IL-17 and IL-22) was measured in supernatants.Of the 20 recruited patients, 13 received treatment with rituximab and 7 received placebo. In all patients, IL-17 was produced by CD4-positive, γδTCR-negative cells. After stimulation, there was no difference between patients and healthy controls in ex-vivo production of IL-17 or other cytokines. In all patients there was a general decrease of monocyte- and T-cell-derived cytokines after transplantation, except for IL-17. There was no difference between patients who received rituximab and patients who received placebo.A single dose of rituximab treatment added to standard immunosuppressive therapy in renal transplant patients did not influence the production of IL-17 or other monocyte- or T-cell derived cytokines after ex-vivo stimulation.

B‐cells and IL‐4 promote methylcholanthrene‐induced carcinogenesis but there is no evidence for a role of T/NKT‐cells and their effector molecules (Fas‐ligand, TNF‐α, perforin)

Mice deficient either in subtypes of immune cells, cytokines or lytic pathways have been subjected to chemical carcinogenesis by methylcholanthrene to evaluate whether these components of the immune system affect tumor development. Inbred mice of the same genotype but from different sources differed in tumor development in magnitude comparable to that previously attributed to differences in immunocompetence. This suggested that genetic drift between separate inbred colonies of mice and/or environmental factors (e.g., transport of the animals) influenced carcinogenesis. Therefore, littermates were used as control in subsequent experiments. Although deficiency of T-cells, NKT-cells, perforin, Fas-ligand, TNF-α-receptor failed to reveal significant differences in tumor development, the presence of B-cells and IL-4 enhanced tumor development under similar experimental conditions.

Lymphocytes are dispensable for glomerulonephritis but required for renal interstitial fibrosis in matrix defect-induced Alport renal disease

One current theory for the emergence of glomerular nephritis implicates Th1-type cellular responses associated with delayed-type hypersensitivity, involving T cells and macrophages. Using a mouse model for progressive glomerulonephritis, we investigate the role of B and T cells in the pathogenesis of glomerular inflammation. Deletion of α3 chain of type IV collagen in mice (α3(IV) collagen null mice) results in GBM defects, glomerulonephritis and tubulointerstitial inflammation, fibrosis and significant immune infiltration including activated B- and T-lymphocytes. To evaluate the contribution of lymphocytes to the pathogenesis of glomerulonephritis and renal fibrosis, we generated mice that are deficient in both the α3(IV) collagen and Rag-1 (α3/Rag-1 DKO). Lymphocyte deficiency significantly reduces fibrosis in the renal interstitium, but ultrastructural GBM defects persist. Interestingly, glomerulonephritis in the double null mice persists at a similar level with comparable proteinuria. Here we demonstrate that despite the presence of B-cell and T-cells in the inflamed glomeruli, their deletion does not impede the emergence of glomerulonephritis but has a negative impact on the progression of renal interstitial fibrosis.

B-Cells Promote Intra-Islet CD8+ Cytotoxic T-Cell Survival to Enhance Type 1 Diabetes

To determine the role of B-cells in promoting CD8(+) T-cell-mediated beta cell destruction in chronically inflamed islets. RESEARCH DESIGN AND METHODS-RIP: TNFalpha-NOD mice were crossed to B-cell-deficient NOD mice, and diabetes development was monitored. We used in vitro antigen presentation assays and in vivo administration of bromodeoxyuridine coupled to flow cytometry assays to assess intra-islet T-cell activation in the absence or presence of B-cells. CD4(+)Foxp3(+) activity in the absence or presence of B-cells was tested using in vivo depletion techniques. Cytokine production and apoptosis assays determined the capacity of CD8(+) T-cells transform to cytotoxic T-lymphocytes (CTLs) and survive within inflamed islets in the absence or presence of B-cells. B-cell deficiency significantly delayed diabetes development in chronically inflamed islets. Reintroduction of B-cells incapable of secreting immunoglobulin restored diabetes development. Both CD4(+) and CD8(+) T-cell activation was unimpaired by B-cell deficiency, and delayed disease was not due to CD4(+)Foxp3(+) T-cell suppression of T-cell responses. Instead, at the CTL transition stage, B-cell deficiency resulted in apoptosis of intra-islet CTLs. In inflamed islets, B-cells are central for the efficient intra-islet survival of CTLs, thereby promoting type 1 diabetes development.

Resistance and susceptibility to Salmonella infections

Salmonella infect humans and animals world-wide causing a spectrum of diseases including enteric fever, gastroenteritis and septicaemia. A number of mechanisms of host resistance to salmonellosis have been identified in the mouse typhoid model. In mice, salmonellae usually reside inside phagocytes and dendritic cells localized within discrete pathological lesions surrounded by normal tissue. Bacterial growth in the tissues is controlled by NADPH oxidase-dependent and iNOS-dependent anti-microbial functions of resident and inflammatory phagocytes and is under the control of H-2 genes and the Nramp1 gene. The concerted action of a number of cytokines (TNFα, IFNγ, IL-12, IL-18, IL-15), the contribution of CD4 TCR-α/β T-cells, the presence of B-cells and antibodies are essential for host resistance to this bacterium. Observations on the increased incidence of Salmonella infections in immunocompromised patients have revealed some effector mechanisms that control these infections in humans. Deficiencies in components of the innate immune system including gastric secretion, neutrophil and macrophage functions predispose individuals to salmonellosis. A higher incidence of salmonellosis is seen also in patients with antibody deficiencies, defects in cell-mediated immunity and deficiencies in Th1 cytokines (IL-12, IFNγ) or cytokine receptors (IL-12R β1 subunit, IFNγR chains 1 and 2).

Assessment of male CVID patients for mutations in the Btk gene: how many have been misdiagnosed?

The presentation of hypogammaglobulinaemia in young males without a family history of immunodeficiency can pose a diagnostic problem. In the past, the presence of B-cells has suggested a diagnosis of common variable immunodeficiency (CVID), although genotypic analysis has now clarified that individuals with B cells may have mutations in their Btk gene. In order to address the issue of how many male individuals with a clinical diagnosis of CVID do in fact have mutations in the Btk gene, we analysed a group of 24 male patients. Single-strand conformation polymorphism (SSCP) analysis was used to screen the patient cohort for mutations in the Btk gene. Given the size of the Btk gene, the number of patients in the cohort and the amount of available DNA, multiplex PCR reactions were utilized to span the 19 exons and promoter region of the gene. Where abnormal migration patterns were observed with multiplex PCR reactions, in nine of the 24 patients, the individual Btk gene fragments were re-amplified and analysed again by SSCP. Following this analysis, four patients continued to demonstrate abnormal SSCP migration patterns. However, direct sequencing of the relevant Btk gene fragments for these four CVID patients revealed a mutation in only one patient. The mutation was the previously described polymorphism at position 2031 of Btk gene within exon 18. These results indicate that caution should be taken with the application of SSCP analysis to mutation detection. While it has a role to play in screening large patient cohorts, direct sequencing is a necessary adjunct to such analysis. Finally, the clinical diagnosis of CVID in this cohort successfully excluded males with Btk mutations.

Characterization of BIS20x3, a bi-specific antibody activating and retargeting T-cells to CD20-positive B-cells.

This paper describes a bi-specific antibody, which was called BIS20x3. It retargets CD3ɛ-positive cells (T-cells) to CD20-positive cells and was obtained by hybrid–hybridoma fusion. BIS20x3 could be isolated readily from quadroma culture supernatant and retained all the signalling characteristics associated with both of its chains. Cross-linking of BIS20x3 on Ramos cells leads to DNA fragmentation percentages similar to those obtained after Rituximab-cross-linking. Cross-linking of BIS20x3 on T-cells using cross-linking F(ab′)2-fragments induced T-cell activation. Indirect cross-linking of T-cell-bound BIS20x3 via Ramos cells hyper-activated the T-cells. Furthermore, it was demonstrated that BIS20x3 effectively re-targets T-cells to B-cells, leading to high B-cell cytotoxicity. The results presented in this paper show that BIS20x3 is fully functional in retargeting T-cells to B-cells and suggest that B-cell lymphomas may represent ideal targets for T-cell retargeting bi-specific antibodies, because the retargeted T-cell is maximally stimulated in the presence of B-cells. Additionally, since B-cells may up-regulate CD95/ Fas expression upon binding of CD20-directed antibodies, B-cells will become even more sensitive for T-cell mediated killing via CD95L/ Fas L, and therefore supports the intention to use T-cell retargeting bi-specific antibodies recognizing CD20 on B-cell malignancies as a treatment modality for these diseases. © 2001 Cancer Research Campaign http://www.bjcancer.com

Acute Kidney Graft Rejection Morphology and immunology

Human kidney allo-transplantation is a successful treatment for end-stage renal failure. The main complication is acute rejection. Although much information has been accumulated on the genetic factors, the clinical and morphological features and the immunological mechanisms involved in acute rejection much remains to be learned. Histological evaluation of needle biopsies is considered one of the most valuable tools in monitoring the transplant. However, very few parameters specific for acute rejection exist and the histological evaluation is complicated by a limited knowledge of the morphology and immunology in well-functioning allografts. The study was undertaken to enlighten the morphological and immunological alterations in the renal allotransplant by biopsiing patients consecutively before and after transplantation. Special emphasis was by immunohistochemistry put on activated cellular infiltrates and adhesion molecules. Studies with cultured human tubular cells were performed to obtain information on mechanisms involved in the regulation of MHC molecules and the intercellular adhesion molecule-1 (ICAM-1). In situ hybridization formats were developed in order to investigate donor-recipient traffic of cellular components and to evaluate the possible influence of cytomegalovirus-infection. Finally, renal changes induced by cyclosporine was sought in a group of patients with chronic uveitis receiving long-term cyclosporine treatment. Arteritis and endocapillary glomerulitis was found to be the only reliable parameters specific to acute rejection. All other morphological parameters showed a continuum of changes from nonrejecting to rejecting patients. Thus, tubulitis and dense mononuclear cellular infiltrates were strongly indicative of acute rejection. Immunohistochemically, strong expression of ICAM-1, vascular cellular adhesion molecule-1 and MHC class II antigens on tubular and endothelial cells along with interleukin-2-receptor bearing infiltrates of T-lymphocytes and significant presence of macrophages were highly correlated with acute rejection. Contrarily, the phenotype of T-lymphocytes including the ratio of CD4+/CD8(+)-lymphocytes, the presence of B-cells or deposits of immunoglobulins and complement factors showed no significant correlation in patients with acute rejection. The in vitro studies confirmed that cytokines such as interleukin-1, tumor necrosis factor and gamma-interferon produced by inflammatory cells are involved in the regulation of ICAM-1 and MHC class II antigens on likely target cells such as tubular epithelial cells. Renal CMV-infection was rare. CMV was not found to induce any changes specifically associated with acute or chronic rejection. Cyclosporine induced tubular atrophy, interstitial fibrosis, glomerulosclerosis and hyaline arteriolar degeneration in kidneys from long-term treated uveitis patients but not in renal transplanted patients. Conclusively, the study confirms the value of pre- and postoperative renal biopsies for the monitoring of renal transplantation. It also stresses the importance of the implementation of molecular biological techniques to obtain more information on the immunological and inflammatory processes involved in acute rejection.