T-cell Mitogen Research Articles

Novel immunomodulatory effects of phytanic acid and its related substances in mice

Phytanic acid is one of the constituents of animal products with possible health benefits through improving lipid and glucose metabolism; however, its immunomodulatory effects remain undetermined. The in vitro effects of phytanic acid and its related substances on T-cell functions were investigated. Mouse splenocytes were stimulated by T-cell mitogens and incubated with phytanic acid, phytol, and pristanic acid followed by evaluation of cell proliferation and cytokine production. All phytanic acid-related substances significantly reduced IFN-γ, IL-4, and IL-10 production, with varying potencies, and had no significant effects on IL-2 production. Moreover, IL-17A production was inhibited by phytol and phytanic acid. Phytanic acid elicited immunomodulatory effects without inhibition of T-cell proliferation, and its effective concentration was less than 10 µM, which corresponds to the serum concentration of healthy humans. The present study suggests that phytanic acid has a potentially beneficial effect for amelioration of T-cell mediated autoimmune diseases.

Dibromoacetic Acid Induces Thymocyte Apoptosis by Blocking Cell Cycle Progression, Increasing Intracellular Calcium, and the Fas/FasL Pathway in Vitro.

Dibromoacetic acid (DBAA), a haloacetic acid found in drinking water as a disinfection by-product, can cause many adverse effects, including immunotoxicity. In a previous study, we confirmed that DBAA can induce obvious immunotoxicity in mice but that the underlying mechanisms are not clearly understood. In our current study, we confirmed that DBAA induced cytotoxicity and apoptosis in thymocytes isolated from mice by a range of DBAA concentrations (0, 5, 10, 20, or 40 μM). The data showed that DBAA exposure led to a significant decrease in proliferative responses to T-cell mitogens and obvious inhibition in the production of cytokines interleukin-2 and interleukin-4. We found obvious morphological changes of apoptosis in thymocytes and observed the percentage of apoptotic thymocytes to increase significantly as the DBAA concentration increased. Further investigation showed that DBAA can cause G0/G1 arrest in cell cycle analysis, increase intracellular calcium ([Ca(2+)]i) levels, increase the expression of Fas/FasL proteins, and decrease the expression of Bcl-2 protein. It is concluded that in vitro exposure to DBAA can lead to marked cytotoxicity and apoptosis among thymocytes, and the mechanism involved is strongly related to blocking cell cycle progression, increasing intracellular calcium, and increasing Fas/FasL expressions.

Functional analysis of membrane-bound complement regulatory protein on T-cell immune response in ginbuna crucian carp.

Complements have long been considered to be a pivotal component in innate immunity. Recent researches, however, highlight novel roles of complements in T-cell-mediated adaptive immunity. Membrane-bound complement regulatory protein CD46, a costimulatory protein for T cells, is a key molecule for T-cell immunomodulation. Teleost CD46-like molecule, termed Tecrem, has been newly identified in common carp and shown to function as a complement regulator. However, it remains unclear whether Tecrem is involved in T-cell immune response. We investigated Tecrem function related to T-cell responses in ginbuna crucian carp. Ginbuna Tecrem (gTecrem) proteins were detected by immunoprecipitation using anti-common carp Tecrem monoclonal antibody (mAb) and were ubiquitously expressed on blood cells including CD8α(+) and CD4(+) lymphocytes. gTecrem expression on leucocyte surface was enhanced after stimulation with the T-cell mitogen, phytohaemagglutinin (PHA). Coculture with the anti-Tecrem mAb significantly inhibited the proliferative activity of PHA-stimulated peripheral blood lymphocytes, suggesting that cross-linking of Tecrems on T-cells interferes with a signal transduction pathway for T-cell activation. These findings indicate that Tecrem may act as a T-cell moderator and imply that the complement system in teleost, as well as mammals, plays an important role for linking adaptive and innate immunity.

Macrophage migration inhibitory factor has a permissive role in concanavalin A-induced cell death of human hepatoma cells through autophagy.

Concanavalin A (ConA) is a lectin and T-cell mitogen that can activate immune responses. In recent times, ConA-induced cell death of hepatoma cells through autophagy has been reported and its therapeutic effect was confirmed in a murine in situ hepatoma model. However, the molecular mechanism of ConA-induced autophagy is still unclear. As macrophage migration inhibitory factor (MIF), which is a proinflammatory cytokine, can trigger autophagy in human hepatoma cells, the possible involvement of MIF in ConA-induced autophagy was investigated in this study. We demonstrated that cell death is followed by an increment in MIF expression and secretion in the ConA-stimulated human hepatoma cell lines, HuH-7 and Hep G2. In addition, ConA-induced autophagy and cell death of hepatoma cells were blocked in the presence of an MIF inhibitor. Knockdown of endogenous MIF by small hairpin RNA confirmed that MIF is required for both ConA-induced autophagy and death of hepatoma cells. Furthermore, signal pathway studies demonstrated that ConA induces signal transducer and activator of transcription 3 (STAT3) phosphorylation to trigger MIF upregulation, which in turn promotes Bcl-2/adenovirus E1B 19 kDa-interacting protein 3 (BNIP3)-dependent autophagy. By using a murine in situ hepatoma model, we further demonstrated that MIF contributes to anti-hepatoma activity of ConA by regulating STAT3–MIF–BNIP3-dependent autophagy. In summary, our findings uncover a novel role of MIF in lectin-mediated anti-hepatoma activities by regulating autophagy.

Effects of arsenic disulfide on proliferation, cytokine production, and frequencies of CD4+, CD8+, and regulatory T cells in mitogen-activated human peripheral blood mononuclear cells

Influence of arsenic disulfide (As2S2) on human immune cells has little been investigated. Effects of As2S2 on proliferation, cytokine production, and frequencies of CD4+ T, CD8+ T and CD4+CD25+Foxp3+ regulatory T cells in mitogen-activated human peripheral blood mononuclear cells were examined. Anti-proliferative effects of As2S2 on peripheral blood mononuclear cells activated by T-cell mitogen were assessed by a colorimetric assay. Cytokine concentrations in the culture medium were measured with beads-array procedures followed by flow cytometry. CD4+ T cells, CD8+ T cells and CD4+CD25+Foxp3+ regulatory T cells were stained with fluorescence-labeled specific antibodies followed by flow cytometry analysis. As2S2 at 1–10μM significantly suppressed mitogen-activated proliferation of peripheral blood mononuclear cells (p<0.05). As2S2 at 10μM inhibited production of IL-6, -10, -17A, tumor necrosis factor-α, and interferon-γ from the activated peripheral blood mononuclear cells, though the effects were not statistically significant. As2S2 at 10μM significantly suppressed the frequencies of CD4+ T and CD8+ T cells (p<0.05), whereas significantly enhanced the frequency of CD4+CD25+Foxp3+ regulatory T cells (p<0.05). The data suggest that As2S2 attenuates T cell-mediated immunity by not only suppressing the proliferation of T cells and cytokine release but also increasing the frequency of regulatory T cells. T cell-mediated autoimmunity contributes to bone marrow failure in myelodysplastic syndrome (MDS), and thus the above As2S2 effects are beneficial for the treatment of MDS patients.

Post-Spaceflight (STS-135) Mouse Splenocytes Demonstrate Altered Activation Properties and Surface Molecule Expression.

Alterations in immune function have been documented during or post-spaceflight and in ground based models of microgravity. Identification of immune parameters that are dysregulated during spaceflight is an important step in mitigating crew health risks during deep space missions. The in vitro analysis of leukocyte activity post-spaceflight in both human and animal species is primarily focused on lymphocytic function. This report completes a broader spectrum analysis of mouse lymphocyte and monocyte changes post 13 days orbital flight (mission STS-135). Analysis includes an examination in surface markers for cell activation, and antigen presentation and co-stimulatory molecules. Cytokine production was measured after stimulation with T-cell mitogen or TLR-2, TLR-4, or TLR-5 agonists. Splenocyte surface marker analysis immediate post-spaceflight and after in vitro culture demonstrated unique changes in phenotypic populations between the flight mice and matched treatment ground controls. Post-spaceflight splenocytes (flight splenocytes) had lower expression intensity of CD4+CD25+ and CD8+CD25+ cells, lower percentage of CD11c+MHC II+ cells, and higher percentage of CD11c+MHC I+ populations compared to ground controls. The flight splenocytes demonstrated an increase in phagocytic activity. Stimulation with ConA led to decrease in CD4+ population but increased CD4+CD25+ cells compared to ground controls. Culturing with TLR agonists led to a decrease in CD11c+ population in splenocytes isolated from flight mice compared to ground controls. Consequently, flight splenocytes with or without TLR-agonist stimulation showed a decrease in CD11c+MHC I+, CD11c+MHC II+, and CD11c+CD86+ cells compared to ground controls. Production of IFN-γ was decreased and IL-2 was increased from ConA stimulated flight splenocytes. This study demonstrated that expression of surface molecules can be affected by conditions of spaceflight and impaired responsiveness persists under culture conditions in vitro.

Sublethal red tide toxin exposure in free-ranging manatees (Trichechus manatus) affects the immune system through reduced lymphocyte proliferation responses, inflammation, and oxidative stress

The health of many Florida manatees (Trichechus manatus latirostris) is adversely affected by exposure to blooms of the toxic dinoflagellate, Karenia brevis. K. brevis blooms are common in manatee habitats of Florida’s southwestern coast and produce a group of cyclic polyether toxins collectively referred to as red tide toxins, or brevetoxins. Although a large number of manatees exposed to significant levels of red tide toxins die, several manatees are rescued from sublethal exposure and are successfully treated and returned to the wild. Sublethal brevetoxin exposure may potentially impact the manatee immune system. Lymphocyte proliferative responses and a suite of immune function parameters in the plasma were used to evaluate effects of brevetoxin exposure on health of manatees rescued from natural exposure to red tide toxins in their habitat. Blood samples were collected from rescued manatees at Lowry Park Zoo in Tampa, FL and from healthy, unexposed manatees in Crystal River, FL. Peripheral blood leukocytes (PBL) isolated from whole blood were stimulated with T-cell mitogens, ConA and PHA. A suite of plasma parameters, including plasma protein electrophoresis profiles, lysozyme activity, superoxide dismutase (SOD) activity, and reactive oxygen/nitrogen (ROS/RNS) species, was also used to assess manatee health. Significant decreases (p<0.05) in lymphocyte proliferation were observed in ConA and PHA stimulated lymphocytes from rescued animals compared to non-exposed animals. Significant correlations were observed between oxidative stress markers (SOD, ROS/RNS) and plasma brevetoxin concentrations. Sublethal exposure to brevetoxins in the wild impacts some immune function components, and thus, overall health, in the Florida manatee.

Cytocompatibility and immunomodulatory properties of wood based nanofibrillated cellulose

Cellulose nanofibrils (CNFs), unique and promising natural materials have gained significant attention recently for biomedical applications, due to their special biomechanical characteristics, surface chemistry, good biocompatibility and low toxicity. However, their long bio-persistence in the organism may provoke immune reactions and this aspect of CNFs has not been studied to date. Therefore, the aim of this work was to examine and compare the cytocompatibility and immunomodulatory properties of CNFs in vitro. CNFs (diameters of 10–70 nm; lengths of a few microns) were prepared from Norway spruce (Picea abies) by mechanical fibrillation and high pressure homogenisation. L929 cells, rat thymocytes or human peripheral blood mononuclear cells (PBMNCs) were cultivated with CNFs. None of the six concentrations of CNFs (31.25 µg/ml–1 mg/ml) induced cytotoxicity and oxidative stress in the L929 cells, nor induced necrosis and apoptosis of thymocytes and PBMNCs. Higher concentrations (250 µg/ml–1 mg/ml) slightly inhibited the metabolic activities of the L929 cells as a consequence of inhibited proliferation. The same concentrations of CNFs suppressed the proliferation of PBMNCs to phytohemaglutinine, a T-cell mitogen, and the process was followed by down-regulation of interleukin-2 (IL-2) and interferon-γ production. The highest concentration of CNFs inhibited IL-17A, but increased IL-10 and IL-6 production. The secretion of pro-inflammatory cytokines, IL-1β and tumor necrosis factor-α as well as Th2 cytokine (IL-4), remained unaltered. In conclusion, the results suggest that these CNFs are cytocompatible nanomaterial, according to current ISO criteria, with non-inflammatory and non-immunogenic properties. Higher concentrations seem to be tolerogenic to the immune system, a characteristic very desirable for implantable biomaterials.

Changes of Cytokine and Chemokine mRNA Expression in Whole Blood Cells from Active Pulmonary Tuberculosis Patients after T-Cell Mitogen and Mycobacterium tuberculosis Specific Antigen Stimulation

Tuberculosis (TB) is one of the major global health problems and it has been estimated that in 5~10% of Mycobacterium tuberculosis (MTB)-infected individuals, the infection progresses to an active disease. Numerous cytokines and chemokines regulate immunological responses at cellular level including stimulation and recruitment of wide range of cells in immunity and inflammation. In the present study, the mRNA expression levels of eight host immune markers containing of IFN-γ, TNF-α, IL-2R, IL-4, IL-10, CXCL9, CXCL10, and CXCL11 in whole blood cells from active pulmonary TB patients were measured after T-cell mitogen (PHA) and MTB specific antigens (ESAT-6, CFP-10, and TB7.7). Among the TH1-type factors, IFN-γ mRNA expression was peaked at 4 h, TNF-α and IL-2R mRNA expression was significantly high at the late time points (24 h) in active TB patients, TH2-type cytokine (IL4 and IL10) mRNA expression levels in both active TB and healthy controls samples did not changed significantly, and the mRNA expression of the three IFN-γ-induced chemokines (CXCL9, CXCL10, and CXCL11) were peaked at the late time points (24 h) in active TB patients after MTB specific antigen stimulation. In conclusion, the mRNA expression patterns of the TB-related immune markers in response to the T-cell mitogen (PHA) differed from those in response to MTB specific antigens and these findings may helpful for understanding the relationship between MTB infection and host immune markers in a transcripts level.

Polyethylene glycol-coated graphene oxide attenuates antigen-specific IgE production and enhanced antigen-induced T-cell reactivity in ovalbumin-sensitized BALB/c mice.

BackgroundGraphene oxide (GO) is a promising nanomaterial for potential application in the versatile field of biomedicine. Graphene-based nanomaterials have been reported to modulate the functionality of immune cells in culture and to induce pulmonary inflammation in mice. Evidence pertaining to the interaction between graphene-based nanomaterials and the immune system in vivo remains scarce. The present study investigated the effect of polyethylene glycol-coated GO (PEG-GO) on antigen-specific immunity in vivo.MethodsBALB/c mice were intravenously administered with a single dose of PEG-GO (0.5 or 1 mg/kg) 1 hour before ovalbumin (OVA) sensitization, and antigen-specific antibody production and splenocyte reactivity were measured 7 days later.ResultsExposure to PEG-GO significantly attenuated the serum level of OVA-specific immunoglobulin E. The production of interferon-γ and interleukin-4 by splenocytes restimulated with OVA in culture was enhanced by treatment with PEG-GO. In addition, PEG-GO augmented the metabolic activity of splenocytes restimulated with OVA but not with the T-cell mitogen concanavalin A.ConclusionCollectively, these results demonstrate that systemic exposure to PEG-GO modulates several aspects of antigen-specific immune responses, including the serum production of immunoglobulin E and T-cell functionality.

Intravenous injection of a foamy virus vector to correct canine SCID-X1

AbstractCurrent approaches to hematopoietic stem cell (HSC) gene therapy involve the collection and ex vivo manipulation of HSCs, a process associated with loss of stem cell multipotency and engraftment potential. An alternative approach for correcting blood-related diseases is the direct intravenous administration of viral vectors, so-called in vivo gene therapy. In this study, we evaluated the safety and efficacy of in vivo gene therapy using a foamy virus vector for the correction of canine X-linked severe combined immunodeficiency (SCID-X1). In newborn SCID-X1 dogs, injection of a foamy virus vector expressing the human IL2RG gene resulted in an expansion of lymphocytes expressing the common γ chain and the development of CD3+ T lymphocytes. CD3+ cells expressed CD4 and CD8 coreceptors, underwent antigen receptor gene rearrangement, and demonstrated functional maturity in response to T-cell mitogens. Retroviral integration site analysis in 4 animals revealed a polyclonal pattern of integration in all dogs with evidence for dominant clones. These results demonstrate that a foamy virus vector can be administered with therapeutic benefit in the SCID-X1 dog, a clinically relevant preclinical model for in vivo gene therapy.

Effects of vitamin K3 and K5 on proliferation, cytokine production, and regulatory T cell-frequency in human peripheral-blood mononuclear cells

AimsThe effects of vitamin K (VK) derivatives VK3 and VK5 on human immune cells have not been extensively investigated. We examined the effects of VK3 and VK5 on proliferation, apoptosis, cytokine production, and CD4+CD25+Foxp3+ regulatory T (Treg) cell-frequency in human peripheral blood mononuclear cells (PBMCs) activated by T cell mitogen in vitro. Main methodsAnti-proliferative effects of VK3 and VK5 on T-cell mitogen activated PBMCs were assessed by WST assay procedures. Apoptotic cells were determined as Annexin V positive/propidium iodide (PI) negative cells. Cytokine concentrations in the supernatant of the culture medium were measured with bead-array procedures followed by analysis with flow cytometry. The CD4+CD25+Foxp3+Treg cells in mitogen-activated PBMCs were stained with fluorescence-labeled specific antibodies followed by flow cytometry. Key findingsVK3 and VK5 suppressed the mitogen-activated proliferation of PBMCs significantly at 10–100μM (p<0.05). The data also suggest that VK3 and VK5 promote apoptosis in the mitogen-activated T cells. VK3 and VK5 significantly inhibited the production of tumor necrosis factor (TNF) α, interleukin (IL)-4, -6, and -10 from the activated PBMCs at 10–100μM (p<0.05). In contrast, VK3 and VK5 significantly increased Treg cell-frequency in the activated PBMCs at concentrations more than 10μM (p<0.001). SignificanceOur data suggest that VK3 and VK5 attenuate T cell mediated immunity by inhibiting the proliferative response and inducing apoptosis in activated T cells.

Morphological and functional changes in the spleen of mice offspring at different stages of postnatal development after a single immunostimulating impact on maternal organism in early pregnancy.

We studied the effect of short-term activation of the maternal immune system with T-cell mitogen concanavalin A at the early terms of pregnancy on the postnatal development of the spleen in the offspring. It was found that single immunostimulatory exposure prior to the formation of the fetal immune system delays the postnatal development of the spleen until the beginning of puberty and impairs the formation of splenic lymphatic nodules with the predominant development of germinal centers as well as increases the number of mast cells in this organ.

Clinicohematological correlation and chromosomal breakage analysis in suspected Fanconi anemia patients of India.

Introduction:The management of patients with aplastic anemia, to an extent, depends on the etiology i.e., inherited or acquired. The classical Chromosomal breakage study involves detection of chromosomal breakage or aberrations (breaks, gaps, rearrangements, radials, exchanges, endoreduplications) in peripheral blood cells after culture with a T-cell mitogen and a DNA clastogenic (cross-linking) agent, such as diepoxybutane (DEB) or mitomycin C (MMC). The testing needs to be performed in laboratory with appropriate expertise in Fanconi Anemia testing. The present study was undertaken to find out the frequency of inherited aplastic anemia in North India.Materials and Methods:This study was carried out at the Department of Molecular Biology and Transplant Immunology, Indraprastha Apollo hospital, New Delhi. The study includes retrospective analysis of 528 aplastic anemia patients whose samples were tested at our department for Chromosomal breakage study during the period 2007 to 2011. Respective age and sex matched healthy controls were also processed for chromosomal breakage study. Patient's habitat, clinical symptoms, differential blood count and history of drug exposure were documented for all patients referred to us, whereever available. Relative risk was estimated by odds ratio (OR) with 95% confidence interval (CI) in matched cases and controls.Conclusion:A significant increase in chromosomal breakages was seen in 13.1% patients. The survival data documented for 100 patients suggested 60% mortality.

Различия в морфологических изменениях тимуса у потомства самок мышей, подвергшихся на ранних сроках беременности иммуностимулирующему воздействию, после введения эндотоксина грамотрицательных бактерий

The relation between maternal immune response to bacterial, viral and other antigens in pregnancy and postnatal development and function of offspring immune system is little studied. The aim of the research was to study morphological changes of the thymus in the offspring of female mice exposed in early pregnancy single immune-stimulated у effects of T-cell mitogen concanavalin, and control of females after the introduction of the half-lethal dose of endotoxin gram-negative bacteria. The experiment was performed in 44 male C57BL/6 mice at the age of 2,5 weeks. The animals were removed from the experiment through 24 and 48h. after the introduction of lipopolysaccharide of E. coli in a dose of 15 mg/kg. Morphological and histological, physiological changes of thymus mice in the control and experimental groups have similar nature (thymic involution, migration mature thymocytes, reducing the number of fat cells). In the offspring exposed to prenatal exposure, thymic involution and migration mature thymocytes are developing more slowly and to a lesser extent. These data show a decrease in the immune system reactivity offspring subjected to early prenatal development of a massive influence of cytokines secreted by their mother´s lymphocytes under the influence of concanavalin A.

Morpholology of immune system of offspring after stimulation of maternal immune system in early pregnancy

Stimulation of maternal immune system in early pregnancy with Concanavalin A, a T-cell mitogen, prior to formation of fetal immune system impairs development of the offspring’s spleen and thymus. Our findings demonstrate that short-term exposure of pregnant murine dams to Concanavalin A, leads to retardation of postnatal development of offspring’s spleen and reduction of lymphocytes count in thymus medulla and accelerated formation of thymic corpuscles.

Autocrine/Paracrine Function of Nicotinic Acid Adenine Dinucleotide Phosphate (NAADP) for Glucose Homeostasis in Pancreatic β-Cells and Adipocytes

Nicotinic acid adenine dinucleotide phosphate (NAADP) is a second messenger for mobilizing Ca(2+) from intracellular stores in various cell types. Extracellular application of NAADP has been shown to elicit intracellular Ca(2+) signals, indicating that it is readily transported into cells. However, little is known about the functional role of this NAADP uptake system. Here, we show that NAADP is effectively transported into selected cell types involved in glucose homeostasis, such as adipocytes and pancreatic β-cells, but not the acinar cells, in a high glucose-dependent manner. NAADP uptake was inhibitable by Ned-19, a NAADP mimic; dipyridamole, a nucleoside inhibitor; or NaN3, a metabolic inhibitor or under Ca(2+)-free conditions. Furthermore, NAADP was found to be released from pancreatic islets upon stimulation by high glucose. Consistently, administration of NAADP to type 2 diabetic mice improved glucose tolerance. We propose that NAADP is functioning as an autocrine/paracrine hormone important in glucose homeostasis. NAADP is thus a potential antidiabetic agent with therapeutic relevance.

Micronutrient supplementation and T cell-mediated immune responses in patients with tuberculosis in Tanzania.

Limited studies exist regarding whether incorporating micronutrient supplements during tuberculosis (TB) treatment may improve cell-mediated immune response. We examined the effect of micronutrient supplementation on lymphocyte proliferation response to mycobacteria or T-cell mitogens in a randomized trial conducted on 423 patients with pulmonary TB. Eligible participants were randomly assigned to receive a daily dose of micronutrients (vitamins A, B-complex, C, E, and selenium) or placebo at the time of initiation of TB treatment. We found no overall effect of micronutrient supplements on lymphocyte proliferative responses to phytohaemagglutinin or purified protein derivatives in HIV-negative and HIV-positive TB patients. Of HIV-negative TB patients, the micronutrient group tended to show higher proliferative responses to concanavalin A than the placebo group, although the clinical relevance of this finding is not readily notable. The role of nutritional intervention in this vulnerable population remains an important area of future research.

Severity of the TGN1412 trial disaster cytokine storm correlated with IL‐2 release

AimTo determine if cytokine release with a solid phase assay is predictive of adverse responses for a range of therapeutic mAbs.MethodsCytokine ELISAs and a multi-array system were used to compare responses generated by different therapeutic mAbs using a solid phase assay. Flow cytometry was employed to determine the cellular source of those cytokines.ResultsOnly TGN1412 and muromonab-CD3 stimulated CD4+ T-cell mediated cytokine release characterized by significant (all P < 0.0001) IFNγ, TNFα, IL-2, IL-4, IL-5, IL-10, IL-12, IL-13, IL-17 and IL-22 release, comparable with T-cell mitogen. Significantly greater (P < 0.0001) IL-2 release with TGN1412 (2894–6051 pg ml−1) compared with muromonab-CD3 (62–262 pg ml−1) differentiated otherwise comparable cytokine responses. Likewise, TGN1412 stimulated significantly more (P = 0.0001) IL-2 producing CD4+ T-cells than muromonab-CD3 and induced Th1, Th2, Th17 and Th22 subsets that co-release this cytokine. Significant TNFα release was observed with bevacizumab (P = 0.0001), trastuzumab (P = 0.0031) and alemtuzumab (P = 0.0177), but no significant IL-2 release. TGN1412 and muromonab-CD3 caused pro-inflammatory cytokine release despite significantly (both P < 0.0001) increasing numbers of T-cells with a regulatory phenotype.ConclusionsThe severity of the adverse response to TGN1412 compared with muromonab-CD3 and other therapeutic mAbs correlates with the level of IL-2 release.

Toxic Shock Syndrome: Characterization of Human Immune Responses to TSST-1 and Evidence for Sensitivity Thresholds

Noninvasive vaginal infections by Staphylococcus aureus strains producing the superantigen TSST-1 can cause menstrual toxic shock syndrome (mTSS). With the objective of exploring the basis for differential susceptibility to mTSS, the relative responsiveness to TSST-1 of healthy women has been investigated. Peripheral blood mononuclear cells from healthy donors were incubated with purified TSST-1 or with the T-cell mitogen phytohemmaglutinin (PHA), and proliferation was measured. The concentrations of TSST-1 and PHA required to elicit a response equivalent to 15% of the maximal achievable response (EC15) were determined. Although with PHA, EC15 values were comparable between donors, subjects could be classified as being of high, medium, or low sensitivity based on responsiveness to TSST-1. Sensitivity to TSST-1-induced proliferation was associated with increased production of the cytokines interleukin-2 and interferon-γ. When the entire T lymphocyte population was considered, there were no differences between sensitivity groups with respect to the frequency of cells known to be responsive to TSST-1 (those bearing CD3(+) Vβ2(+)). However, there was an association between sensitivity to TSST-1 and certain HLA-class II haplotypes. Thus, the frequencies of DR7DQ2, DR14DQ5, DR4DQ8, and DR8DQ4 haplotypes were greater among those with high sensitivity, a finding confirmed by analysis of responses to immortalized homozygous B cell lines. Collectively, the results reveal that factors other than neutralizing antibody and the frequency of Vβ2(+) T lymphocytes determine immunological responsiveness to TSST-1. Differential responsiveness of lymphocytes to TSST-1 may form the basis of interindividual variations in susceptibility to mTSS.