CD16+ monocytes represent 5-10% of peripheral blood monocytes in normal individuals and are dramatically expanded in several pathological conditions including sepsis, human immunodeficiency virus 1 ...infection, and cancer. CD16+ monocytes produce high levels of proinflammatory cytokines and may represent dendritic cell precursors in vivo. The mechanisms that mediate the recruitment of CD16+ monocytes into tissues remain unknown. Here we investigate molecular mechanisms of CD16+ monocyte trafficking and show that migration of CD16+ and CD16- monocytes is mediated by distinct combinations of adhesion molecules and chemokine receptors. In contrast to CD16- monocytes, CD16+ monocytes expressed high CX3CR1 and CXCR4 but low CCR2 and CD62L levels and underwent efficient transendothelial migration in response to fractalkine (FKN; FKN/CX3CL1) and stromal-derived factor 1 alpha (CXCL12) but not monocyte chemoattractant protein 1 (CCL2). CD16+ monocytes arrested on cell surface-expressed FKN under flow with higher frequency compared with CD16- monocytes. These results demonstrate that FKN preferentially mediates arrest and migration of CD16+ monocytes and suggest that recruitment of this proinflammatory monocyte subset to vessel walls via the CX3CR1-FKN pathway may contribute to vascular and tissue injury during pathological conditions.
The role of serologic testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in both the clinical and public health settings, will continue to evolve as we gain increasing insight ...into our immune response to the virus. Here, we evaluated four high-throughput serologic tests for detection of anti-SARS-CoV-2 IgG antibodies, from Abbott Laboratories (Abbott Park, IL), Epitope Diagnostics, Inc. (San Diego, CA), Euroimmun (Lubeck, Germany), and Ortho-Clinical Diagnostics (Rochester, NY), using a panel of serially collected serum samples (
= 224) from 56 patients with confirmed coronavirus disease 2019 (COVID-19), healthy donor sera from 2018, and a cross-reactivity serum panel collected in early 2020. The sensitivities of the Abbott, Epitope, Euroimmun, and Ortho-Clinical IgG assays in convalescent-phase serum samples collected more than 14 days post-symptom onset or post-initial positive reverse transcriptase PCR (RT-PCR) result were 92.9% (78/84), 88.1% (74/84), 97.6% (82/84), and 98.8% (83/84), respectively. Among unique convalescent patients, sensitivities of the Abbott, Epitope, Euroimmun, and Ortho-Clinical anti-SARS-CoV-2 IgG assays were 97.3% (36/37), 73% (27/37), 94.6% (35/37), and 97.3% (36/37), respectively. Overall assay specificity/positive predictive values based on a 5% prevalence rate were 99.6%/92.8%, 99.6%/90.6%, 98.0%/71.2%, and 99.6%/92.5%, respectively, for the Abbott, Epitope, Euroimmun, and Ortho-Clinical IgG assays. In conclusion, we show high sensitivity in convalescent-phase sera and high specificity for the Abbott, Euroimmun, and Ortho-Clinical anti-SARS-CoV-2 IgG assays. With the unprecedented influx of commercially available serologic tests for detection of antibodies against SARS-CoV-2, it remains imperative that laboratories thoroughly evaluate such assays for accuracy prior to implementation.
Antibody-dependent cell-mediated cytotoxicity, one of the most prominent modes of action of antitumor antibodies, suffers from important limitations due to the need for optimal interactions with Fcγ ...receptors. In this work, we report the design of a new bispecific antibody format, compact and linker-free, based on the use of llama single-domain antibodies that are capable of circumventing most of these limitations. This bispecific antibody format was created by fusing single-domain antibodies directed against the carcinoembryonic antigen and the activating FcγRIIIa receptor to human Cκ and CH1 immunoglobulin G1 domains, acting as a natural dimerization motif. In vitro and in vivo characterization of these Fab-like bispecific molecules revealed favorable features for further development as a therapeutic molecule. They are easy to produce in Escherichia coli, very stable, and elicit potent lysis of tumor cells by human natural killer cells at picomolar concentrations. Unlike conventional antibodies, they do not engage inhibitory FcγRIIb receptor, do not compete with serum immunoglobulins G for receptor binding, and their cytotoxic activity is independent of Fc glycosylation and FcγRIIIa polymorphism. As opposed to anti-CD3 bispecific antitumor antibodies, they do not engage regulatory T cells as these latter cells do not express FcγRIII. Studies in nonobese diabetic/severe combined immunodeficient gamma mice xenografted with carcinoembryonic antigen-positive tumor cells showed that Fab-like bispecific molecules in the presence of human peripheral blood mononuclear cells significantly slow down tumor growth. This new compact, linker-free bispecific antibody format offers a promising approach for optimizing antibody-based therapies.
The expression of FcgammaR by human skin-derived mast cells of the MC(TC) type was determined in the current study. Expression of mRNA was analyzed with microarray gene chips and RT-PCR; protein by ...Western blotting and flow cytometry; function by release of beta-hexosaminidase, PGD(2), leukotriene C(4) (LTC(4)), IL-5, IL-6, IL-13, GM-CSF, and TNF-alpha. FcgammaRIIa was consistently detected along with FcepsilonRI at the mRNA and protein levels; FcgammaRIIc was sometimes detected only by RT-PCR; but FcgammaRIIb, FcgammaRI, and FcgammaRIII mRNA and protein were not detected. FcgammaRIIa-specific mAb caused skin MC(TC) cells to degranulate and secrete PGD(2), LTC(4), GM-CSF, IL-5, IL-6, IL-13, and TNF-alpha in a dose-dependent fashion. FcepsilonRI-specific mAb caused similar amounts of each mediator to be released with the exception of LTC(4), which was not released by this agonist. Simultaneous but independent cross-linking of FcepsilonRI and FcgammaRIIa did not substantially alter mediator release above or below levels observed with each agent alone. Skin MC(TC) cells sensitized with dust-mite-specific IgE and IgG, when coaggregated by Der p2, exhibited enhanced degranulation compared with sensitization with either IgE or IgG alone. These results extend the known capabilities of human skin mast cells to respond to IgG as well as IgE-mediated signals.
Abstract Toxocariasis is a zoonotic disease of worldwide distribution. The connection between parasitic diseases and conditions that depress the immune system, such as the use of immunosuppressive ...drugs, has been studied. The purpose of this study was to evaluate the effect of Cyclosporine A (CsA) on the intensity of infection, humoral response and gene transcription of interleukins IL-4, IL-10 and IL-12 in mice experimentally infected with Toxocara canis. To this end, mice were divided into two groups treated with CsA (G1: 10 mg/Kg and G2: 50 mg/kg), the G3 and G4 group received PBS. After the last administration of the drug or PBS (orally every 48 hours for 15 days), groups G1, G2 and G3 were inoculated with 1200 eggs of T. canis. Was collected blood samples on days zero, 15 and 30 days post-inoculation (PI), for ELISA test and the mice were euthanized 30 days PI. The organs and striated muscle tissue were collected for the recovery of larvae. The splenocytes were analyzed by RT-PCR. The intensity of infection in the mice treated with 50 mg/kg of CsA was 65.5% higher than in the control group (p=0.001). An analysis of the kinetics of anti-Toxocara antibody revealed that the groups treated with CsA showed significantly higher mean levels of antibodies on day 15 PI. The transcription of the three tested interleukins showed no statistical difference between G2 and G3 (control). It was concluded that the immunosuppression triggered by CsA (50 mg/Kg) favored the establishment of a larger number of T. canis larvae without, however, altering immunoglobulin production and IL-4, IL-10 and IL-12 transcription on day 30 PI.
Resumo A toxocaríase é uma zoonose de distribuição mundial. A conexão entre doenças parasitárias e condições que deprimem o sistema imunológico, como o uso de drogas imunossupressoras, tem sido estudada. O objetivo deste estudo foi avaliar o efeito da Ciclosporina A (CsA) na intensidade da infecção, resposta humoral e transcrição gênica das interleucinas IL-4, IL-10 e IL-12 em camundongos experimentalmente infectados com Toxocara canis. Para tanto, os camundongos foram divididos em dois grupos tratados com CsA (G1: 10 mg/Kg e G2: 50 mg/kg), os grupos G3 e G4 receberam PBS. Após a última administração da droga ou PBS (via oral a cada 48 horas por 15 dias), os grupos G1, G2 e G3 foram inoculados com 1200 ovos de T. canis. Foram coletadas amostras de sangue nos dias zero, 15 e 30 dias pós-inoculação (PI), para teste de ELISA e os camundongos foram eutanasiados 30 dias PI. Os órgãos e tecido muscular estriado foram coletados para a recuperação das larvas. Os esplenócitos foram analisados por RT-PCR. A intensidade da infecção nos camundongos tratados com 50 mg/kg de CsA foi 65,5% maior do que no grupo controle (p=0,001). Uma análise da cinética do anticorpo anti-Toxocara revelou que os grupos tratados com CsA apresentaram níveis médios de anticorpos significativamente maiores no dia 15 PI. A transcrição das três interleucinas testadas não apresentou diferença estatística entre G2 e G3 (controle). Concluiu-se que a imunossupressão desencadeada pela CsA (50 mg/Kg) favoreceu o estabelecimento de um maior número de larvas de T. canis sem, no entanto, alterar a produção de imunoglobulinas e a transcrição de IL-4, IL-10 e IL-12 no dia 30 PI.
Antibody responses are an important part of immunity after Coronavirus Disease 2019 (COVID-19) vaccination. However, antibody trajectories and the associated duration of protection after a second ...vaccine dose remain unclear. In this study, we investigated anti-spike IgG antibody responses and correlates of protection after second doses of ChAdOx1 or BNT162b2 vaccines for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the United Kingdom general population. In 222,493 individuals, we found significant boosting of anti-spike IgG by the second doses of both vaccines in all ages and using different dosing intervals, including the 3-week interval for BNT162b2. After second vaccination, BNT162b2 generated higher peak levels than ChAdOX1. Older individuals and males had lower peak levels with BNT162b2 but not ChAdOx1, whereas declines were similar across ages and sexes with ChAdOX1 or BNT162b2. Prior infection significantly increased antibody peak level and half-life with both vaccines. Anti-spike IgG levels were associated with protection from infection after vaccination and, to an even greater degree, after prior infection. At least 67% protection against infection was estimated to last for 2-3 months after two ChAdOx1 doses, for 5-8 months after two BNT162b2 doses in those without prior infection and for 1-2 years for those unvaccinated after natural infection. A third booster dose might be needed, prioritized to ChAdOx1 recipients and those more clinically vulnerable.
•There is a high immunity rate (81%) after the first SARS-CoV-2 circulation in New Caledonia.•SARS-CoV-2 infection rates are higher in the North Province of New Caledonia and in the Oceanian ...communities.•There was a high previous exposure to other human coronaviruses.
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This study aimed to determine the seroprevalence of immunoglobulin G antibodies targeting SARS-CoV-2 and other human coronaviruses after the first circulation of SARS-CoV-2 in New Caledonia, Pacific region.
Blood samples were collected to detect the presence of SARS-CoV-2 immunoglobulin G antibodies. The sampling took place between July 2021 and July 2022 but was interrupted after the first circulation of SARS-CoV-2 (September 2021-March 2022) in New Caledonia. Data on ethnicity, age, gender, main residence, and anteriority of COVID-19 and vaccination were collected and analyzed.
A total of 747 participants, representative of New Caledonia's adult population, were included in the study. We found that 81% of the population had antibody responses to SARS-CoV-2 at the end of July 2022. The vaccination rate was 75%, whereas infections had affected 40% of the population. Individuals aged >45 years were significantly more vaccinated than those aged 18-44 years (80%, 95% confidence interval 74-84%). Oceanians were the most infected (50%, 95% confidence interval 42-57%).
In New Caledonia, we show a high immunity rate (81%) after the first waves of SARS-CoV-2 circulation and the vaccination campaign. The analyses showed spatial heterogeneities in the infection rate across the territory and revealed that Oceanians were the most infected. Our study also highlighted high exposure of New Caledonia's population to other human coronaviruses.
Convalescent plasma increases SARS-CoV-2 clearance in COVID-19, especially in patients lacking preexisting antibodies.
In hospitalized patients with COVID-19 receiving convalescent plasma, does ...conversion to a positive SARS-CoV-2 IgG status provide mortality benefit in patients who lacked SARS-CoV-2 IgG?
This observational study included consecutive hospitalized patients with COVID-19 who received convalescent plasma under the Expanded Access Program from April through August 2020. SARS-CoV-2 N-based IgG antibody enzyme-linked immunosorbent assay measurements before and after transfusion were recorded. Outcomes of patients without preexisting antibodies who demonstrated seroconversion immediately after receipt of convalescent plasma were compared with those who did not show seroconversion. Hospital mortality was the primary outcome.
Two hundred seventy-five hospitalized patients received convalescent plasma during the study period. SARS-CoV-2 IgG was collected from 234 patients. One hundred ten patients (47%) showed seropositive findings and 124 patients (53%) showed seronegative findings before transfusion. Among the seronegative group, 63 patients (50.8%) demonstrated seroconversion after plasma transfusion, whereas 61 patients (49.2%) continued to show seronegative findings despite transfusion. Age, sex, BMI, Sequential Organ Failure Assessment score, and receipt of high-titer plasma were similar across all subgroups. Seroconversion after transfusion was not associated with survival at hospital discharge (OR, 1.9; 95% CI, 0.7-4.9; P = .17).
Serologic response after transfusion of convalescent plasma was not shown to be associated with hospital survival in patients with COVID-19 without preexisting SARS-CoV2 IgG antibodies.
Immune recognition of nonself is coordinated through complex mechanisms involving both innate and adaptive responses. Circulating antibodies communicate with effector cells of the innate immune ...system through surface receptors known as Fcγ receptors (FcγRs). The FcγRs are single-pass transmembrane glycoproteins responsible for regulating innate effector responses toward antigenic material. Although immunoglobulin G (IgG) antibodies bind to a range of receptors, including complement receptors and C-type lectins, we have focused on the Fcγ receptors. A total of five functional FcγRs are broadly classified into three families (FcγRI, FcγRII, and FcγRIII) and together aid in controlling both inflammatory and anti-inflammatory responses of the innate immune system. Due to the continued success of monoclonal antibodies in treating cancer and autoimmune disorders, research is typically directed toward improving the interaction of antibodies with the FcγRs through manipulation of IgG properties such as N-linked glycosylation. Biochemical studies using recombinant forms of the FcγRs are often used to quantitate changes in binding affinity, a key indicator of a likely biological outcome. However, analysis of the FcγRs themselves is imperative as recombinant FcγRs differ greatly from those observed in humans. In particular, the N-linked glycan composition is significantly important due to its function in the IgG–FcγR interaction. Here, we present data for the N-linked glycans present on FcγRs produced in NS0 cells, namely, FcγRIa, FcγRIIa, FcγRIIB, FcγRIIIa, and FcγRIIIb. Importantly, these FcγRs demonstrate typical murine glycosylation in the form of α-galactose epitopes, N-glycolylneuraminic acid, and other key glycan properties that are generally expressed in murine cell lines and therefore are not typically observed in humans.
•Unconventional light-diffusing fiber (LDF) plasmonic platform for biosensing.•Novel data analysis methodology for the calculation of the resonance wavelength value.•IgG/anti-IgG in buffer and ...CRP/anti-CRP in serum bioassays implemented and tested on the proposed sensing system.•Thermo-stabilized microfluidic system for the stabilization of the signal and reduction of the noise.
In this work, an unconventional light-diffusing fiber (LDF) plasmonic platform is exploited to efficiently monitor a bio-interaction. The surface plasmon resonance (SPR)-LDF sensor is used to detect the immunoglobulin G (IgG)/anti-IgG interaction as exemplifying bioassay. The IgG bioreceptor was deposited on the gold surface of the SPR-LDF platform, and the biological target was transported through a customized thermo-stabilized flow cell by means of a buffer fluid. Moreover, to test the usability of the proposed SPR-LDF biosensor also for immunosensing in complex matrices, a second assay was conducted by immobilizing anti-C-reactive protein (CRP) and detecting different concentrations of CRP in human serum. An innovative data analysis approach for the extraction of the best value of the resonance wavelength was developed and applied. The obtained results reveal that the unconventional platform represented by the LDF can be successfully exploited for the implementation of SPR-based biosensors with very good performances, also when compared to more common SPR systems.
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