Antibody response to three-dose anti-SARS-CoV-2 mRNA-vaccination in treated solid cancer patients

Solid cancer patients are at higher risk of SARS-CoV-2 infection and severe complications. Moreover, vaccine-induced antibody response is impaired in patients on anticancer treatment. In this retrospective, observational, hypothesis-generating, cohort study, we assessed the antibody response to the third dose of mRNA vaccine in a convenience sample of patients on anticancer treatment, comparing it to that of the primary two-dose cycle. Among 99 patients included, 62.6% were ≥60 years old, 32.3% males, 67.7% with advanced disease. Exactly 40.4% were receiving biological therapy, 16.2% chemotherapy only and 7.1% both treatments. After the third dose, seroconversion rate seems to increase significantly, especially in non-responders to two doses. Heterologous vaccine-type regimen (two-dose mRNA-1273 and subsequent tozinameran or vice versa) results in higher antibody levels. This explorative study suggests that repeated doses of mRNA-vaccines could be associated with a better antibody response in this population. Furthermore, heterologous vaccine-type three-dose vaccination seems more effective in this population. Since this is a hypothesis-generating study, adequately statistically powered studies should validate these results.

Early administration of nirmatrelvir/ritonavir leads to faster negative SARS-CoV-2 nasal swabs than monoclonal antibodies in COVID 19 patients at high-risk for severe disease

PURPOSE

Besides the well-established efficacy in preventing severe COVID-19, the impact of early treatments, namely antivirals and monoclonal antibodies (mAbs), on the time length to negativization of SARS-CoV-2 nasal swabs is still unclear. The aim of this study was to compare the efficacy of different early treatments in reducing the SARS-CoV-2 viral shedding, identifying a single drug that might potentially lead to a more rapid negativization of SARS-CoV-2 nasal swab.

METHODS

This was a single-centre, retrospective, observational study conducted at Ospedale Luigi Sacco in Milan. Data of high-risk COVID-19 patients who received early treatments between 23 December 2021 and March 2023 were extracted. The comparison across treatments was conducted using the Kruskall-Wallis test for continuous variables. Dunn's test with Bonferroni adjustment was performed for post-hoc comparisons of days to negativization. Secondly, a negative binomial regression adjusted for age, sex, number of comorbidities, immunosuppression, and SARS-CoV-2 vaccination status was implemented.

RESULTS

Data from 428 patients receiving early treatments were collected. The majority were treated with Nirmatrelvir/Ritonavir and were affected by SARS-CoV-2 Omicron infection with BA.2 sublineage. The median length time to SARS-CoV-2 nasal swab negativization was 9 days [IQR 7-13 days]. We found that Nirmatrelvir/Ritonavir determined a significant decrease of the length time to SARS-CoV-2 nasal swab negativization compared to mAbs (p = 0.003), but not compared to Remdesivir (p = 0.147) and Molnupiravir (p = 0.156).

CONCLUSION

Our findings highlight the importance of promptly treating high-risk COVID-19 patients with Nirmatrelvir/Ritonavir, as it also contributes to achieving a faster time to negative SARS-CoV-2 nasal swabs.

Maturation of SARS-CoV-2 Spike-specific memory B cells drives resilience to viral escape

Memory B cells (MBCs) generate rapid antibody responses upon secondary encounter with a pathogen. Here, we investigated the kinetics, avidity, and cross-reactivity of serum antibodies and MBCs in 155 SARS-CoV-2 infected and vaccinated individuals over a 16-month time frame. SARS-CoV-2-specific MBCs and serum antibodies reached steady-state titers with comparable kinetics in infected and vaccinated individuals. Whereas MBCs of infected individuals targeted both prefusion and postfusion Spike (S), most vaccine-elicited MBCs were specific for prefusion S, consistent with the use of prefusion-stabilized S in mRNA vaccines. Furthermore, a large fraction of MBCs recognizing postfusion S cross-reacted with human betacoronaviruses. The avidity of MBC-derived and serum antibodies increased over time resulting in enhanced resilience to viral escape by SARS-CoV-2 variants, including Omicron BA.1 and BA.2 sublineages, albeit only partially for BA.4 and BA.5 sublineages. Overall, the maturation of high-affinity and broadly reactive MBCs provides the basis for effective recall responses to future SARS-CoV-2 variants.

Maturation of SARS-CoV-2 Spike-specific memory B cells drives resilience to viral escape

Memory B cells (MBCs) generate rapid antibody responses upon secondary encounter with a pathogen. Here, we investigated the kinetics, avidity and cross-reactivity of serum antibodies and MBCs in 155 SARS-CoV-2 infected and vaccinated individuals over a 16-month timeframe. SARS-CoV-2-specific MBCs and serum antibodies reached steady-state titers with comparable kinetics in infected and vaccinated individuals. Whereas MBCs of infected individuals targeted both pre- and postfusion Spike (S), most vaccine-elicited MBCs were specific for prefusion S, consistent with the use of prefusion-stabilized S in mRNA vaccines. Furthermore, a large fraction of MBCs recognizing postfusion S cross-reacted with human betacoronaviruses. The avidity of MBC-derived and serum antibodies increased over time resulting in enhanced resilience to viral escape by SARS-CoV-2 variants, including Omicron BA.1 and BA.2 sub-lineages, albeit only partially for BA.4 and BA.5 sublineages. Overall, the maturation of high-affinity and broadly-reactive MBCs provides the basis for effective recall responses to future SARS-CoV-2 variants.

Anti-SARS-CoV-2 Immunoglobulin Isotypes, and Neutralization Activity Against Viral Variants, According to BNT162b2-Vaccination and Infection History

Purpose

To compare SARS-CoV-2 antigen-specific antibody production and plasma neutralizing capacity against B.1 wild-type-like strain, and Gamma/P.1 and Delta/B.1.617.2 variants-of-concern, in subjects with different Covid-19 disease and vaccination histories.

Methods

Adult subjects were: 1) Unvaccinated/hospitalized for Covid-19; 2) Covid-19-recovered followed by one BNT162b2 vaccine dose; and 3) Covid-19-naïve/2-dose BNT162b2 vaccinated. Multiplex Luminex® immunoassays measured IgG, IgA, and IgM plasma levels against SARS-CoV-2 receptor-binding domain (RBD), spike-1 (S), and nucleocapsid proteins. Neutralizing activity was determined in Vero E6 cytopathic assays.

Results

Maximum anti-RBD IgG levels were similar in Covid-19‑recovered individuals 8‒10 days after single-dose vaccination and in Covid-19-naïve subjects 7 days after 2nd vaccine dosing; both groups had ≈2‑fold higher anti-RBD IgG levels than Unvaccinated/Covid-19 subjects tracked through 2 weeks post-symptom onset. Anti-S IgG expression patterns were similar to RBD within each group, but with lower signal strengths. Viral antigen-specific IgA and IgM levels were more variable than IgG patterns. Anti-nucleocapsid immunoglobulins were not detected in Covid-19-naïve subjects. Neutralizing activity against the B.1 strain, and Gamma/P.1 and Delta/B.1.617.2 variants, was highest in Covid‑19-recovered/single-dose vaccinated subjects; although neutralization against the Delta variant in this group was only 26% compared to B.1 neutralization, absolute anti-Delta titers suggested maintained protection. Neutralizing titers against the Gamma and Delta variants were 33‒77% and 26‒67%, respectively, versus neutralization against the B.1 strain (100%) in the three groups.

Conclusion

These findings support SARS-CoV-2 mRNA vaccine usefulness regardless of Covid-19 history, and confirm remarkable protection provided by a single vaccine dose in people who have recovered from Covid-19.

Anti-tumour necrosis factor α antibodies and circulating lymphocyte phenotypes in inflammatory bowel disease

OBJECTIVE

Circulating lymphocyte subtypes are not fully explored parameters for monitoring chronic T cell activation during inflammatory bowel disease (IBD). Tumor necrosis factor α (TNFα), one of the main mediators of IBD related inflammation induces expression of CD70 on T cells. CD70 limits T cell expansion and controls CD27 receptor on activated B lymphocytes. Aim of this study was to assess the number and the frequency of CD70+ T cells and CD27+ B cells in IBD patients during inactive phase of the disease under or without anti-TNFα treatment.

DESIGN

We studied 91 patients with inactive IBD, 31 untreated, 29 treated with infliximab (IFX), and 31 treated with adalimumab (ADA). Lymphocyte phenotypes were assessed by flow cytometry using anti-CD45, CD19, CD27, CD3, and CD70 monoclonal antibodies. IFX and ADA actual capacity of TNFα neutralization in serum was estimated by the recoveryELISA technique.

RESULTS

Whereas CD3+ T cells were increased in treated compared to untreated patients, the percentage of the CD70+ T cells was significantly lower in treated patients indicating a 'cooling' effect of the biological therapy. This effect differs between samples according to the therapeutic range of the circulating drug. Although the CD19+ B-cell percentage tended to be lower in treated patients, CD19+27+ memory B cells did not show significant differences between groups.

CONCLUSIONS

Frequency of peripheral blood CD70+ T cells was significantly reduced by treatment with anti-TNFα antibodies. Monitoring of this parameter of T cells can give better insight to the disease progression and therapy application in IBD patients.

H3K4me3 Histone ChIP-Seq Analysis Reveals Molecular Mechanisms Responsible for Neutrophil Dysfunction in HIV-Infected Individuals

Peripheral neutrophils in HIV-infected individuals are characterized by impairment of chemotaxis, phagocytosis, bactericidal activity, and oxidative burst ability regardless of whether patients are receiving antiretroviral therapy or not. Neutrophil dysfunction leads not only to increased susceptibility to opportunistic infections but also to tissue damage through the release of reactive oxygen species (ROS), proteases, and other potentially harmful effector molecules contributing to AIDS progression. In this study, we demonstrated high levels of histone H3 lysine K4 trimethylated (H3K4me3) and dysregulation of DNA transcription in circulating neutrophils of HIV-infected subjects. This dysregulation was accompanied by a deficient response of neutrophils to LPS, impaired cytokine/chemokine/growth factor synthesis, and increased apoptosis. Chromatin immunoprecipitation sequencing (ChIPseq) H3K4me3 histone analysis revealed that the most spectacular abnormalities were observed in the exons, introns, and promoter-TSS regions. Bioinformatic analysis of Gene Ontology, including biological processes, molecular function, and cellular components, demonstrated that the main changes were related to the genes responsible for cell activation, cytokine production, adhesive molecule expression, histone remodeling via upregulation of methyltransferase process, and downregulation of NF-κB transcription factor in canonical pathways. Abnormalities within H3K4me3 implicated LPS-mediated NF-κB canonical activation pathway that was a result of low amounts of κB DNA sites within histone H3K4me3, low NF-κB (p65 RelA) and TLR4 mRNA expression, and reduced free NF-κB (p65 RelA) accumulation in the nucleus. Genome-wide survey of H3K4me3 provided evidence that chromatin modifications lead to an impairment within the canonical NF-κB cell activation pathway causing the neutrophil dysfunction observed in HIV-infected individuals.

SARS-CoV-2 seroprevalence trends in healthy blood donors during the COVID-19 outbreak in Milan

BACKGROUND

The Milan metropolitan area in Northern Italy was among the most severely hit by the SARS-CoV-2 outbreak. The aim of this study was to examine the seroprevalence trends of SARS-CoV-2 in healthy asymptomatic adults, and the risk factors and laboratory correlates of positive tests.

MATERIALS AND METHODS

We conducted a cross-sectional study in a random sample of blood donors, who were asymptomatic at the time of evaluation, at the beginning of the first phase (February 24th to April 8th 2020; n=789). Presence of IgM/IgG antibodies against the SARS-CoV-2-Nucleocapsid protein was assessed by a lateral flow immunoassay.

RESULTS

The test had a 100/98.3 sensitivity/specificity (n=32/120 positive/negative controls, respectively), and the IgG test was validated in a subset by an independent ELISA against the Spike protein (n=34, p<0.001). At the start of the outbreak, the overall adjusted seroprevalence of SARS-CoV-2 was 2.7% (95% CI: 0.3-6%; p<0.0001 vs 120 historical controls). During the study period, characterised by a gradual implementation of social distancing measures, there was a progressive increase in the adjusted seroprevalence to 5.2% (95% CI: 2.4-9.0; 4.5%, 95% CI: 0.9-9.2% according to a Bayesian estimate) due to a rise in IgG reactivity to 5% (95% CI: 2.8-8.2; p=0.004 for trend), but there was no increase in IgM+ (p=not significant). At multivariate logistic regression analysis, IgG reactivity was more frequent in younger individuals (p=0.043), while IgM reactivity was more frequent in individuals aged >45 years (p=0.002).

DISCUSSION

SARS-CoV-2 infection was already circulating in Milan at the start of the outbreak. The pattern of IgM/IgG reactivity was influenced by age: IgM was more frequently detected in participants aged >45 years. By the end of April, 2.4-9.0% of healthy adults had evidence of seroconversion.

SARS-CoV-2 seroprevalence trends in healthy blood donors during the COVID-19 outbreak in Milan

BACKGROUND

The Milan metropolitan area in Northern Italy was among the most severely hit by the SARS-CoV-2 outbreak. The aim of this study was to examine the seroprevalence trends of SARS-CoV-2 in healthy asymptomatic adults, and the risk factors and laboratory correlates of positive tests.

MATERIALS AND METHODS

We conducted a cross-sectional study in a random sample of blood donors, who were asymptomatic at the time of evaluation, at the beginning of the first phase (February 24^th to April 8^th 2020; n=789). Presence of IgM/IgG antibodies against the SARS-CoV-2-Nucleocapsid protein was assessed by a lateral flow immunoassay.

RESULTS

The test had a 100/98.3 sensitivity/specificity (n=32/120 positive/negative controls, respectively), and the IgG test was validated in a subset by an independent ELISA against the Spike protein (n=34, p<0.001). At the start of the outbreak, the overall adjusted seroprevalence of SARS-CoV-2 was 2.7% (95% CI: 0.3-6%; p<0.0001 vs 120 historical controls). During the study period, characterised by a gradual implementation of social distancing measures, there was a progressive increase in the adjusted seroprevalence to 5.2% (95% CI: 2.4-9.0; 4.5%, 95% CI: 0.9-9.2% according to a Bayesian estimate) due to a rise in IgG reactivity to 5% (95% CI: 2.8-8.2; p=0.004 for trend), but there was no increase in IgM⁺ (p=not significant). At multivariate logistic regression analysis, IgG reactivity was more frequent in younger individuals (p=0.043), while IgM reactivity was more frequent in individuals aged >45 years (p=0.002).

DISCUSSION

SARS-CoV-2 infection was already circulating in Milan at the start of the outbreak. The pattern of IgM/IgG reactivity was influenced by age: IgM was more frequently detected in participants aged >45 years. By the end of April, 2.4-9.0% of healthy adults had evidence of seroconversion.

Mapping Neutralizing and Immunodominant Sites on the SARS-CoV-2 Spike Receptor-Binding Domain by Structure-Guided High-Resolution Serology

Analysis of the specificity and kinetics of neutralizing antibodies (nAbs) elicited by SARS-CoV-2 infection is crucial for understanding immune protection and identifying targets for vaccine design. In a cohort of 647 SARS-CoV-2-infected subjects, we found that both the magnitude of Ab responses to SARS-CoV-2 spike (S) and nucleoprotein and nAb titers correlate with clinical scores. The receptor-binding domain (RBD) is immunodominant and the target of 90% of the neutralizing activity present in SARS-CoV-2 immune sera. Whereas overall RBD-specific serum IgG titers waned with a half-life of 49 days, nAb titers and avidity increased over time for some individuals, consistent with affinity maturation. We structurally defined an RBD antigenic map and serologically quantified serum Abs specific for distinct RBD epitopes leading to the identification of two major receptor-binding motif antigenic sites. Our results explain the immunodominance of the receptor-binding motif and will guide the design of COVID-19 vaccines and therapeutics.

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SARS-CoV-2 RBD is immunodominant and accounts for 90% of serum neutralizing activity

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RBD antibodies decline with a half-life of ∼50 days, but their avidity increases

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Structural definition of a SARS-CoV-2 RBD antigenic map using monoclonal antibodies

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ACE2-binding site dominates SARS-CoV-2 polyclonal neutralizing antibody responses

Genomic characterization and phylogenetic analysis of SARS-COV-2 in Italy

This report describes the isolation, molecular characterization, and phylogenetic analysis of the first three complete genomes of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) isolated from three patients involved in the first outbreak of COVID‐19 in Lombardy, Italy. Early molecular epidemiological tracing suggests that SARS‐CoV‐2 was present in Italy weeks before the first reported cases of infection.

MS CD49d+CD154+ Lymphocytes Reprogram Oligodendrocytes into Immune Reactive Cells Affecting CNS Regeneration

The critical aspect in multiple sclerosis (MS) progression involves insufficient regeneration of CNS resulting from deficient myelin synthesis by newly generated oligodendrocytes (OLs). Although many studies have focused on the role of autoreactive lymphocytes in the inflammatory-induced axonal loss, the problem of insufficient remyelination and disease progression is still unsolved. To determine the effect of myelin-specific lymphocytes on OL function in MS patients and in a mouse model of MS, we cultured myelin induced MS CD49d⁺CD154⁺ circulating lymphocytes as well as Experimental Autoimmune Encephalomyelitis (EAE) mouse brain-derived T and memory B cells with maturing oligodendrocyte precursor cells (OPCs). We found that myelin-specific CD49d⁺CD154⁺ lymphocytes affected OPC maturation toward formation of immune reactive OLs. Newly generated OLs were characterized by imbalanced myelin basic protein (MBP) and proteolipid protein (PLP) production as well as proinflammatory chemokine/cytokine synthesis. The analysis of cellular pathways responsible for OL reprogramming revealed that CD49d⁺CD154⁺ lymphocytes affected miRNA synthesis by dysregulation of polymerase II activity. miR-665 and ELL3 turned out to be the main targets of MS myelin-specific lymphocytes. Neutralization of high intracellular miR-665 concentration restored miRNA and MBP/PLP synthesis. Together, these data point to new targets for therapeutic intervention promoting CNS remyelination.

Structural Basis for Broad HIV-1 Neutralization by the MPER-Specific Human Broadly Neutralizing Antibody LN01

Potent and broadly neutralizing antibodies (bnAbs) are the hallmark of HIV-1 protection by vaccination. The membrane-proximal external region (MPER) of the HIV-1 gp41 fusion protein is targeted by the most broadly reactive HIV-1 neutralizing antibodies. Here, we examine the structural and molecular mechansims of neutralization by anti-MPER bnAb, LN01, which was isolated from lymph-node-derived germinal center B cells of an elite controller and exhibits broad neutralization breadth. LN01 engages both MPER and the transmembrane (TM) region, which together form a continuous helix in complex with LN01. The tilted TM orientation allows LN01 to interact simultaneously with the peptidic component of the MPER epitope and membrane via two specific lipid binding sites of the antibody paratope. Although LN01 carries a high load of somatic mutations, most key residues interacting with the MPER epitope and lipids are germline encoded, lending support for the LN01 epitope as a candidate for lineage-based vaccine development.

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bNAb LN01 neutralizes 92% of a 118-strain virus panel

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LN01 targets the HIV-1 gp41 MPER, the TM region, and lipids

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LN01-complexed MPER forms a continuous helix with TM

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Most LN01 paratope residues interacting with MPER-TM and lipids are germline encoded

Activating Killer Immunoglobulin Receptors and HLA-C: a successful combination providing HIV-1 control

Several studies demonstrated a relevant role of polymorphisms located within the HLA-B and -C loci and the Killer Immunoglobulin Receptors (KIRs) 3DL1 and 3DS1 in controlling HIV-1 replication. KIRs are regulatory receptors expressed at the surface of NK and CD8+ T-cells that specifically bind HLA-A and -B alleles belonging to the Bw4 supratype and all the -C alleles expressing the C1 or C2 supratype. We here disclose a novel signature associated with the Elite Controller but not with the long-term nonprogressor status concerning 2DS activating KIRs and HLA-C2 alleles insensitive to miRNA148a regulation. Overall, our findings support a crucial role of NK cells in the control of HIV-1 viremia.

Polymorphisms in Fas gene is associated with HIV-related lipoatrophy in Thai patients

The present study aimed to evaluate the role of genetic polymorphisms in the emergence of lipoatrophy or lipodystrophy in HIV-infected patients with antiretroviral therapy (ART) in Thailand. Position 455 upstream of the Apolipoprotein C3 gene (ApoC3 T-455C, rs2854116), codon 64 of the Beta3 adrenergic receptor gene (ARβ3 Tcod64C, rs4994), and position 670 upstream of the Fas gene (Fas A-670G, rs1800682) were genotyped in 829 HIV-infected Thai patients who had started ART. Crude and adjusted incidence rate ratios (IRR) were calculated using Poisson regression. The serum levels of cholesterol, triglycerides, high-density lipoprotein (HDL), and low-density lipoprotein (LDL) were also analyzed. Multivariate analysis revealed an association between the Fas -670AA genotype, but not the ApoC3 -455 or ARβ3 cod64 genotypes, with the incidence of lipoatrophy after adjusting for gender and stavudine (d4T)-containing regimens (IRR=1.72, 95% CI=1.20-2.45, p=0.003). However, ApoC3 -455C homozygous patients showed elevated serum levels of triglycerides, while this genotype did not affect serum total cholesterol, HDL, or LDL levels in patients with lipoatrophy or lipodystrophy. In contrast, the ARβ3 cod64 genotype did not show any significant association with the serum levels of cholesterol, triglycerides, HDL, or LDL. In conclusion, Fas -670AA affected the incidence of lipoatrophy in HIV-1-infected Thai patients, while the ApoC3 -455C allele affected the serum levels of triglycerides. These results confirmed the role of genetics in the development of ART-related metabolic disorders.

Expression of interleukin-15 and interleukin-15Rα in monocytes of HIV type 1-infected patients with different courses of disease progression

Interleukin-15 (IL-15) enhances the effector mechanisms of anti-HIV immune responses and thus is considered a potential adjuvant of HIV-1 vaccine. However, there are a lack of data concerning the relationships between IL-15 expression and regulation in HIV-1-infected patients and the course of disease progression. We found that IL-15, but not IL-15Rα, is expressed at significantly higher levels in the CD14(+) monocytes [stimulated or not with interferon (IFN)-γ] of long-term nonprogressors (LTNP) than in those of HIV-1 progressors or healthy controls. There was no between-group difference in the amounts of soluble IL-15 released from the cells. We also found that like the healthy controls, the LTNP expressed the IL-15 and IL-15Rα genes in a more coordinated manner than the progressors. Our findings show that there are significant differences in IL-15 expression between patients with different courses of HIV infection, and that the coordinated expression of the IL-15 and IL-15Rα genes is dysregulated in patients with progressive disease. They also provide important information concerning the mechanisms of infection and the potential use of IL-15 as a therapeutic agent.

Switching to unboosted atazanavir reduces bilirubin and triglycerides without compromising treatment efficacy in UGT1A1*28 polymorphism carriers

OBJECTIVES

Hyperbilirubinaemia is a frequent complication of atazanavir-containing antiretroviral therapy and its severity is related to UDP-glucuronosyl transferase (UGT) 1A1*28 polymorphism. The aim of this study was to evaluate the safety and outcome of unboosted atazanavir-containing regimens based on the genetic constitution.

METHODS

Fifty-one HIV-1-infected patients on boosted atazanavir were prospectively enrolled in the study. Twenty-five patients with a UGT1A1*28 allele switched to 400 mg of unboosted atazanavir.

RESULTS

At baseline, UGT1A1 heterozygous and homozygous patients had significantly higher bilirubin levels than wild-type (P = 0.012 and P < 0.001, respectively). After ritonavir removal, a reduction was observed in total bilirubin (from 4.09 to 1.82 mg/dL; P < 0.001), γ-glutamyl transpeptidase (P = 0.015), triglycerides (P = 0.03) and total cholesterol (P = 0.05). No significant changes in CD4 T cell count and no increases in viral load were observed 12 months after unboosting. Plasma drug monitoring after ritonavir removal revealed the presence of therapeutic atazanavir concentrations in all patients except one with poor therapy adherence.

CONCLUSIONS

UGT1A1*28 is significantly related to hyperbilirubinaemia in HIV-1 patients receiving atazanavir. Genotyping before the initiation of antiretroviral therapy can reduce the emergence of severe hyperbilirubinaemia. Unboosted atazanavir-containing therapy is safe and efficacious in patients with an undetectable viral load with a UGT1A1*28 polymorphism, allowing the use of atazanavir in patients otherwise likely unable to receive it.

Immunological determinants in a mouse model of chemical-induced asthma after multiple exposures

In a mouse model of chemical-induced asthma, we investigated the effects of multiple challenges, using toluene diisocyanate (TDI), a known cause of occupational asthma. On days 1 and 7, BALB/c mice received TDI or vehicle (acetone/olive oil). On days 10, 13 and 16 the mice received an intranasal instillation of TDI. Ventilatory function (Penh) was monitored by whole body plethysmography for 40 min after each challenge. Reactivity to methacholine was measured 22 h later. Pulmonary inflammation, TNF-alpha and MIP-2 levels were assessed 24 h after the last challenge by broncho-alveolar lavage (BAL). Other immunological parameters included total IgE, lymphocyte sub-populations in auricular and cervical lymph nodes, and IL-4, IFN-gamma and IL-13 levels in supernatants of lymph node cells, cultured with or without concanavalin A. Early ventilatory function and airway reactivity increased in all groups that received a dermal application and one or multiple intranasal challenges of TDI. After multiple challenges, lung inflammation was characterized by neutrophils (approximately 15%), and eosinophils (approximately 4%), along with an increase in BAL MIP-2 and TNF-alpha levels. The auricular and cervical lymph node cells of all sensitized mice showed an increase in B cells, Th cells and an increased concentration of in vitro release of IL-4, IFN-gamma and IL-13 after stimulation with concanavalin A. Total serum IgE was elevated in dermally TDI-sensitized mice. This protocol including multiple challenges results in a model that resembles human asthma, indicating that responses found in the model using a single challenge could be a good first indication for the development of asthma.

Asthmatic symptoms after exposure to ethylenebisdithiocarbamates and other pesticides in the Europit field studies

We conducted a multicenter prospective study to assess the effects of occupational exposure to ethylenebisdithiocarbamate fungicides and/or other pesticides on self-reported asthma and asthmatic symptoms. This multicenter study was conducted among 248 workers exposed to pesticides and 231 non-exposed workers from five field studies. The five field studies were carried out in The Netherlands, Italy, Finland, and two studies in Bulgaria. Subjects constituting this cohort completed a self-administered questionnaire at baseline (before the start of exposure). Ethylenethiourea in urine was determined to assess exposure to ethylenebisdithiocarbamates. In multivariate analyses adjusted for all potential confounders (age, education, residence, smoking, gender, and field study), we found inverse associations, all not statistically significant, between occupational exposure to pesticides and asthma diagnosis (OR 0.41; 95% CI 0.15-1.11), complains of chest tightness (OR 0.60; 95% CI 0.36-1.02), wheeze (OR 0.56; 95% CI 0.32-0.98), asthma attack (OR 0.52; 95% CI 0.12-2.25), and asthma medication (OR 0.79; 95% CI 0.25-2.53). Furthermore, we reported null associations for multivariate analysis using ethylenethiourea as determinant for exposure. Although exposure to pesticides remains a potential health risk, our results do not suggest an association between exposure to ethylenebisdithiocarbamates and/or other pesticides used in our study on asthma and asthmatic symptoms.

Immune effects and exposure to ethylenebisdithiocarbamate pesticides in re-entry workers in the Netherlands

Ethylenebisdithiocarbamates are widely used as fungicides in agriculture. Although EBDC's have a low acute toxicity, they are suspected to have immune effects at low doses. However, little human studies on these effects have been published. In the Netherlands, a study was conducted among pesticide exposed workers aimed at evaluating the short-term and long-term immune effects of exposure and the relation between ethylenebisdithiocarbamate and immune effects. Forty-one re-entry workers and 40 nonexposed controls were medically examined; furthermore, immune parameters were determined in blood, and all participants filled in a questionnaire regarding exposure and outcome parameters. The level of ethylenethiourea in urine was determined as indicator of exposure. No relevant adverse immune effects were found in the pesticide exposed workers compared with the nonexposed controls. Also no exposure response relationship between immune effects and ethylenebisdithiocarbamate in urine was found. This finding might be due to very low exposure levels of the re-entry work but might also be due to a lack of immunotoxicity of ethylenebisdithiocarbamate at normal exposure levels.

Dysfunction of CD4+CD25high T regulatory cells in patients with recurrent aphthous stomatitis

BACKGROUND

Recurrent aphthous stomatitis (RAS) is a chronic inflammatory disease of unknown etiology characterized by recurring formation of painful oral ulcers. RAS may result from oral epithelium damage caused by T-cell-mediated immune response. CD4(+)CD25(+) T regulatory (Treg) cells suppress proliferation and effector functions of other immune cells, and therefore are crucial in regulating the immune response.

METHODS

We tested the function of peripheral CD4(+)CD25(high) Treg cells in active RAS through their ability to inhibit proliferation and cytokine production of conventional CD4(+) T cells. We also attempted to detect the presence of FOXP3 and indoleamine 2,3-dioxygenase (IDO) mRNA in the lesional and non-lesional oral mucosa of RAS patients and healthy individuals using real-time PCR assay.

RESULTS

Treg cells derived from RAS patients were less efficient in the suppression of cytokine production of CD4(+) T effector cells than Treg cells from healthy individuals. Moreover, in RAS, Treg cells were nearly twice less potent in the inhibition of CD4(+)CD25(-) T cell proliferation than in healthy donors. Furthermore, we have demonstrated the decreased proportion of CD4(+)CD25(+)FOXP3(+) Treg cells in peripheral blood of RAS patients compared with controls. We failed to detect FOXP3 mRNA, while IDO mRNA expression was decreased in non-lesional mucosa biopsies from RAS patients compared with ulcer biopsies or normal mucosa from healthy donors.

CONCLUSIONS

These findings suggest that CD4(+)CD25(high) Treg cells are both functionally and quantitatively compromised in RAS and that decreased constitutive expression of IDO in oral mucosa in RAS may lead to the loss of local immune tolerance.

Immunological determinants of ventilatory changes induced in mice by dermal sensitization and respiratory challenge with toluene diisocyanate

The objective of the study was to characterize better the immunologic mechanisms underlying a previously developed animal model of chemical-induced asthma. BALB/c and severe combined immunodeficiency disease (SCID) mice received toluene diisocyanate (TDI) or vehicle on each ear on day 1 and/or day 7. On day 10, they were intranasally challenged with TDI or vehicle. Ventilatory function was monitored by whole body plethysmography for 40 min after challenge. Reactivity to methacholine was measured 23 h later: enhanced pause and actual resistance measurements. Pulmonary inflammation was assessed 1, 6, and 24 h after challenge by bronchoalveolar lavage (BAL). Tumor necrosis factor-alpha and macrophage inflammatory protein (MIP)-2 levels were measured in BAL. Immunological parameters included total IgE, IgG1, and IgG2a in serum, lymphocyte populations in auricular and cervical lymph nodes, and IL-4 and IFN-gamma levels in supernatants of lymph node cells, cultured with or without concanavalin A. Ventilatory changes suggestive of airway obstruction and increased methacholine reactivity were observed in all TDI-sensitized and TDI intranasally instilled mice, except in SCID mice. A neutrophil influx, accompanied by an increase in MIP-2 levels, was found in BAL of all responding groups 6 and 24 h after intranasal challenge. In BALB/c mice an increased level of CD19+ B cells was found in the auricular lymph nodes. IL-4 and IFN-gamma levels were increased in supernatants of concanavalin A-stimulated auricular lymph node cells from BALB/c mice completely treated with TDI. These results indicate that our model is dependent on the presence of lymphocytes, but it is not characterized by a preferential stimulation of Th1 or Th2 lymphocytes.

Validation of a mouse model of chemical-induced asthma using trimellitic anhydride, a respiratory sensitizer, and dinitrochlorobenzene, a dermal sensitizer

BACKGROUND

Occupational asthma can be caused by chemicals. Previously, we established a murine model of immunologically mediated chemical-induced asthma using toluene diisocyanate.

OBJECTIVE

We sought to verify this model using trimellitic anhydride (TMA), a respiratory sensitizer, and 1-chloro-2,4-dinitrobenzene (DNCB), a dermal sensitizer.

METHODS

BALB/c mice received dermal applications (vehicle or chemical) on days 1 and 7. On day 10, they received an intranasal instillation (vehicle or chemical). Whole-body plethysmography (enhanced pause) was used to monitor changes in ventilatory function and methacholine reactivity. Pulmonary inflammation was assessed by using bronchoalveolar lavage (cells, TNF-alpha levels, and macrophage inflammatory protein 2 levels). Immunologic parameters included total serum IgE levels, lymphocyte distribution in auricular and cervical lymph nodes, and IL-4 and IFN-gamma levels in supernatants of lymph node cells incubated with or without concanavalin A.

RESULTS

Mice dermally treated and intranasally challenged with TMA experienced markedly increased enhanced pause immediately after intranasal challenge and increased methacholine reactivity (24 hours later). Mice similarly treated with DNCB did not show any ventilatory changes. Neutrophil influx and increased macrophage inflammatory protein 2 and TNF-alpha levels were found in bronchoalveolar lavage fluid in both TMA- and DNCB-treated mice. The proportion of CD19+ B cells was increased in auricular and cervical lymph nodes of TMA-treated mice. IL-4 and IFN-gamma levels were increased in supernatants of concanavalin A-stimulated auricular and cervical lymph node cells of TMA- or DNCB-treated mice; however, the relative proportions of IL-4 and IFN-gamma levels differed between TMA- and DNCB-treated mice. Serum total IgE levels were increased in TMA-treated mice only.

CONCLUSION

Both compounds induce a mixed T(H)1-T(H)2 response, but only TMA induced ventilatory changes.

CLINICAL IMPLICATIONS

In the workplace avoiding skin contact with chemical sensitizers might be advised to prevent chemical-induced asthma.

Occupational asthma caused by cobalt chloride in a diamond polisher after cessation of occupational exposure: a case report

OBJECTIVES

The inspiration of cobalt containing dust leads to various respiratory symptoms, including asthma and interstitial lung disease. Occupational asthma caused by cobalt chloride has been diagnosed in a 35-year-old patient, who worked as a diamond polishing disc former. The patient presented a 2-year history of dyspnea, cough and symptoms of rhinitis.

MATERIALS AND METHODS

The patient underwent a medical history interview, skin prick tests with common and occupational allergens (cobalt and nickel chloride), and pulmonary function testing both before and after the nasal provocation with 0.05% cobalt chloride. Additionally, the authors analyzed morphological and biochemical changes before and after the specific nasal challenge test. Cell proliferation analysis was also carried out.

RESULTS

Skin prick tests (SPTs) with common environmental allergens were found to be negative, while SPTs with cobalt chloride were positive for all applied solutions. The provocation with cobalt chloride caused a significant increase in the proportion of eosinophils, basophils and albumin during the late allergic reaction. The positive lymphocyte transformation caused by cobalt was also observed.

CONCLUSIONS

Cobalt salts may induce occupational asthma. The mechanism of this asthma may be IgE-mediated. The cobalt-sensitized lymphocytes may play an important role in this disease.

Respiratory response to toluene diisocyanate depends on prior frequency and concentration of dermal sensitization in mice

Occupational asthma is the principal cause of work-related respiratory disease in the industrial world. In the absence of satisfactory models for predicting the potential of low molecular weight chemicals to cause asthma, we verified that dermal sensitization prior to intranasal challenge influences the respiratory response using toluene diisocyanate (TDI), a known respiratory sensitizer. BALB/c mice received TDI or vehicle (acetone/olive oil) on each ear on three consecutive days (days 1, 2, and 3; 0.3 or 3% TDI) or only once (day 1, 1% TDI). On day 7, the mice received similar dermal applications of vehicle or the same concentration of TDI as before ("boost"). On day 10, they received an intranasal dose of TDI (0.1%) or vehicle. Ventilatory function was monitored by whole body plethysmography for 40 min after intranasal application, and reactivity to inhaled methacholine was assessed 24 h later. Pulmonary inflammation was assessed by bronchoalveolar lavage and histology. Mice that received an intranasal dose of TDI without having received a prior dermal application of TDI did not exhibit any ventilatory response or inflammatory changes compared to vehicle controls. In contrast, mice that had received prior application(s) of TDI, even if only on day 7, exhibited the following: ventilatory responses, compatible with bronchoconstriction, immediately after intranasal application with TDI; enhanced methacholine responsiveness 24 h later; and pulmonary inflammation characterized by neutrophils. This was, however, not the case in mice that received the highest dermal amount of TDI (3% on days 1, 2, and 3). These findings suggest that respiratory response to TDI depends on prior frequency and concentration of dermal sensitization in mice.

The lymphocytic cholinergic system and its modulation by organophosphorus pesticides

Clinical and basic mechanism observations reveal interactions between neural and immune systems. These two systems create a complex network for recognizing danger to the host and its protection from outside pathogenic elements as well as from inside overreactions of inflammatory character. Here, we review the interactions of these two systems in relation to the effects of pesticides that clearly involve elements of cholinergic lymphocytic system. We discuss cellular and soluble elements of the immune system, which may be affected by pesticide exposure. We suggest that in-depth studies of the influence of pesticides on lymphocytes may contribute to the development of sensitive methods of measuring early adverse effects appearing in response to pesticide exposure.

Expression and a role of CD30 in regulation of T-cell activity

CD30 receptor has been known for almost 20 years, but its expression and activity are still the subject of many investigations. Its expression was found in different malignancies, and most of the studies regarding CD30 focus on its role in lymphomas. The progress that has already been made in this field is reflected in implementation of CD30 as a target for immunotoxin, which has been tested in phase I study in treating Hodgkin lymphoma. CD30 is present also on normal, activated T cells of all cytokine profiles. However, increased density of CD30 and CD30-mediated Th2 cytokine production provide evidence of its role in determining the activity of T cells toward synthesis of cytokines and involvement in reactions of Th2 characteristics. Pleiotropic signaling mediated by CD30 does not implicate this receptor just as a cytokine costimulator; it proves to be important in several different activities of T cells.

CD30 expression on allergen- and non-allergen-specific T cell lines and its role in cytokine production

Interest in CD30 has mainly focused on its ability to discriminate between T helper (Th)2 and Th1 subpopulations. The role of CD30 as the marker for Th2 cells is still controversial, which may be due to the fact that the expression and the role of CD30 is not fully understood. The data presented in this paper provides information on the expression and activity of CD30 in T cell lines specific to allergen or tuberculin-purified protein derivative (PPD) as the model of Th2 or Th1 responses, respectively. The results have shown that CD30 expression was the highest on T cells stimulated with antigen in the presence of interleukin (IL)-12 and it was present on both cell lines, regardless of antigen specificity. Activation of the CD30 receptor on CD4+ T cells, however, showed differences in mRNA expression for IL-4 between these cells. IL-4 mRNA was induced by CD30 costimulation at the same level as was obtained with anti-CD28 agonistic antibodies in allergen-specific T cells. In PPD-specific T cells this effect was not observed. Additionally, there was no effect of anti-CD30 stimulation on IL-6 mRNA expression in any of the cell lines. Comparison of protein cytokine levels for IL-4 and interferon (IFN)-gamma have shown that the highest production of IL-4 was obtained from allergen-specific T cells costimulated with anti-CD28. Although this effect was much lower in the case of CD30 costimulation, it was still above that of anti-CD3 activation alone. No effect of CD30 activation was observed in regard to IFN-gamma mRNA or protein expression in any cell line. The results of the study showed that the CD30 receptor is not exclusively present on Th2 cells; however, its activity may promote a Th2-dependent reaction by modulating IL-4 production.

[Psychoneuroimmunology. A new approach to the function of immunological system]

The most recent evidence suggests that the immune system responses are not regulated only by the presence of antigens but they are also influenced by the brain and behavior. It has been known for some time that stressful conditions alter the functioning of the immune system. Despite methodological difficulties in the quantitation of stress, and its association with the onset of illness, the concept of the stress impact on susceptibility to several diseases is widely acknowledged. This paper reviews the effects of stress on the endocrine and central nervous systems and presents the interactions between these systems and the immune response after exposure to stress signals.

The effect of IL-18 on IL-12-induced CD30 expression and IL-4 and IFN-gamma production by allergen and PPD specific T cells

CD30 is expressed on activated T cells that, as has been suggested, preferentially produce IFN-gamma. Interleukin 12 increases antigen-induced CD30 expression on T cells and IFN-gamma production. Synthesis of IFN-gamma can be augmented further by IL-18. The aim of our study was to investigate whether IL-18 affects the IL-12 induced CD30 expression and cytokine production by allergen or PPD specific T cells. Mononuclear cells of healthy or atopic volunteers were stimulated with PPD or allergen, respectively, to obtain specific T cell lines. T cells were restimulated with appropriate antigen and antigen-presenting cells in the presence of IL-12, IL-18 or a combination of these cytokines. After 3 days, expression of CD30 was investigated on CD4 and CD8 T cells and IFN-gamma and IL-4 cytokine production was estimated in the culture supernatants. Flow cytometric analyses showed no effect of IL-18 on CD30 expression during IL-12 co-stimulation. At the same time after the optimal stimulation for CD30 expression, the levels of IFN-gamma were high in PPD-stimulated cell lines but have not been up-regulated by IL-18. IFN-gamma levels were much lower in allergen-stimulated T cells and although they were up-regulated by IL-12 there was no additional or synergistic effect from IL-18. IL-18, however, increased production of IL-4 in allergen-stimulated cell lines. Our studies provide new information about IL-18 activity on human cells and question its exclusive role in Th1 mediated responses.

The influence of diesel exhaust particles on mononuclear phagocytic cell-derived cytokines: IL-10, TGF-beta and IL-1 beta

Diesel exhaust particles (DEP) are known to modulate the production of cytokines associated with acute and chronic respiratory symptoms and allergic respiratory disease. Tolerance is an important mechanism through which the immune system can maintain nonresponsiveness to common environmental antigens. We examined the effect of DEP on IL-10 and TGF-beta, cytokines produced by macrophages and repressor (Tr-like) lymphocytes which influence tolerance. Human PBMCs (n = 22) were incubated with 1-100 ng/ml of DEP, and suboptimally primed with LPS. IL-10 gene expression was assessed by the S1 nuclease protection assay, and production of IL-10, TGF-beta, TNF-alpha, IL-1 beta and IL-4 stimulated CD23 was evaluated by ELISA after 24 and 48 h. The effect of the order of exposure to DEP and LPS was evaluated on IL-10 protein and mRNA in cells (1) preincubated with LPS followed by DEP, or (2) exposed first to DEP followed by LPS. IL-10 was further evaluated using benzo[a]pyrene and [alpha]naphthoflavone as a surrogate for the polyaromatic hydrocarbons (PAHs) adsorbed to DEP. Control cells were incubated with carbon black, without PAHs. In PBMCs exposed to DEP with LPS, or preincubated with LPS before DEP, IL-10 production and mRNA fall significantly. TGF-beta is similarly suppressed, IL-1 beta secretion is significantly stimulated, and IL-4 stimulated CD23 release rises in the atopic subjects. In contrast, when DEP is added prior to LPS, IL-10 production rises, and IL-1 beta falls to zero. These effects on IL-10 are reproduced with benzo[a]pyrene and reversed by the coaddition of [alpha]naphthoflavone, its known antagonist. The carbon black fraction has no effect on IL-10 production. The effect of DEP on IL-10 can be inhibitory or stimulatory, depending on the order of exposure to DEP and LPS. Pro-inflammatory cytokines and factors rise when IL-10 is inhibited, and are suppressed when IL-10 is stimulated. These results are duplicated with benzo[a]pyrene, suggesting that the PAH portion of the DEP is the active agent.

[Genetic polymorphism of glutathione s-transferase as a factor predisposing to allergic dermatitis]

In the inductive phase of contact allergic dermatitis, simple chemical compounds (haptens) produce together with epidermic proteins adducts presented by Langerhans cells to T lymphocytes. Binding to protein carrier is a necessary condition of transforming a low-molecular allergen into immunogenic one and evoking immunological reaction. The production of allergen adducts with proteins is conditioned by the presence of electrophilic groups in their molecules, or their acquiring during biotransformation phase I. Active allergen metabolites undergo further alterations during biotransformation phase II which leads most frequently to the decline in their chemical activity and more rapid excretion from the body. The number of reactive metabolites (reactive allergens) available for producing adducts with proteins keeps the balance between activation and deactivation reactions. Glutathione S-transferases play a particular role in the allergens (or their metabolites) deactivation process in biotransformation phase II. These enzymes catalyse reactions responsible for the declined electrophilic potential of allergens (or their metabolites), and thus for the decrease in the number of allergen molecules able to produce protein covalent bindings (adducts). Glutathione S-transferases, occurring in the human cellular cytoplasm belong to five classes: alpha(GST A), mu(GST M), theta(GST P), pi(GST T) and Z(GST Z), as well as to one class present in microsomes. The study indicated the presence of isoenzymes GST T1 and GST M1 in the skin. Both isoforms participate in the process of low-molecular allergen biotransformation. Carriers of defective genes GST T1 and/or GST M1 are more vulnerable to allergenic effect of some allergens, e.g. thimerosal, which is associated with the absence of or decrease in the activity of isoenzymes GST T1 and GST M1.

The effect of antigen stimulation on alpha(4), beta(1) and beta(7) chain integrin expression and function in CD4+ cells

BACKGROUND

The alpha(4) integrin, as alpha(4)beta(1) (VLA-4) or alpha(4)beta(7), is critical for T cell migration and proliferation, although its functional modulation remains poorly understood. We hypothesized that increased receptor density, based on new receptor chain synthesis, was one such mechanism. We examined the surface receptor density of the alpha(4) and beta(1) chains on CD4+CD45RO+ cells, and the mRNA expression of these and the beta(7) chain in response to allergen and nonallergen antigen stimulation.

METHODS

Flow-cytometric analyses for CD49d, CD29, and CD45RO were performed on T cell lines specific for timothy, tetanus, and Candida from atopic and nonatopic donors. RNA was extracted from cells sorted to select CD4+/CD49d-positive cells before and after stimulation. Equivalent amounts of cDNA for beta-actin, alpha(4), beta(1) and beta(7) were used in PCR, and the products were quantified using phosphoimaging.

RESULTS

CD49d expression is heterogeneous on T cell lines and is upregulated by antigen stimulation on CD4+ T cells. The surface expression on CD4+CD45RO+ timothy allergen or tetanus toxoid T cell lines is at least double that found on CD45RO- cells. Antigen stimulation upregulated CD49d expression on the CD4+CD45RO+ subpopulation of both cell lines although it was not as significant as in the case of all CD4+ T cells. CD29 surface expression behaves similarly. Candida had no effect on CD49d or CD29. Messenger RNA expression for the alpha(4) chain (CD49d) is significantly upregulated 48 h following the addition of timothy or tetanus. beta(7) chain expression also rises significantly on both cell lines. beta(1) chain expression increases, but not significantly.

CONCLUSIONS

The surface expression of the CD49d is heterogeneous and much higher on CD4+CD45RO+ cells than on CD4+RO- T cells. The CD49d integrin chain on CD4+ T cells is upregulated following antigen exposure. However, the CD4+CD45RO+ subpopulation is only partially responsible for this increase suggesting other T cells to have this receptor expression upregulated. CD29 expression behaves similarly. Messenger RNA expression increases coordinately for alpha(4), beta(7), and not significantly for beta(1) in these cells. These observations provide a potential mechanism for the selective accumulation of T cells at sites of inflammation, and suggest an important point of intervention for allergic and inflammatory disease.

Expression and function of CD30 on T lymphocytes

T cell receptor, accessory molecules, cytokines are important regulatory factors that determine the development and function of T lymphocytes. Among them are also molecules belonging to superfamily of tumor necrosis factor receptor (TNFR) which beside CD30 include CD27, CD40, TNFR-I and -II, Fas (CD95), OX40, 4-1BB (CDw137), nerve growth factor receptor, lymphotoxin-beta receptor, Apo3/DR3/Ws1-1/lymphocyte associated receptor of death, DR4, DR5/TNF-related apoptosis-inducing ligand, osteoprotegerin, and TNFR-related 2. CD30 recognized originally on Reed-Sternberg cells of Hodgkin's lymphoma became of interest in studies of Th1 and Th2 cell differentiation. This paper shows recent findings regarding CD30 expression and its pleiotropic role in T cell function. It provides information about controversial role of CD30 as Th2 cell differentiation marker and gives concise insight into the function of this receptor as a signal transducing molecule.

CD49d expression and function on allergen-stimulated T cells from blood and airway

The alpha4 chain (CD49d), which constitutes one of the chains of alpha4beta1 (very late activating antigen-4 [VLA-4]) and alpha4beta7 integrins, mediates migration of T cells to extravascular spaces. The interaction between VLA-4 and vascular cell adhesion molecule-1 (VCAM-1) has been shown to be the critical pathway for the selective accumulation of eosinophils and basophils at sites of allergic inflammation. T lymphocytes are also specifically recruited into allergic sites, including the allergic asthmatic airway. Increased numbers of activated CD4+ cells expressing the DR antigen subset of the human leukocyte antigens (HLA-DR) appear in the allergic lung 48 h after allergen inhalation. The mechanisms by which these cells localize into the lung are still unknown. We report that stimulation of allergen-specific T cells with allergen in vitro resulted in enhanced expression of alpha4 chain (CD49d) as measured by receptor density on allergen-specific T-cell lines and T-cell clones. Kinetic studies showed that CD49d density was enhanced over a 24- to 48-h period in a time-dependent fashion, and was coordinately upregulated with HLA-DR expression. We also demonstrated that increased expression of CD49d on T-cell lines 24 h and 48 h after stimulation correlated with increased adhesion to the CS-1 fragment of fibronectin. In contrast, lymphocyte function-associated antigen-1b (LFA-1b) (CD11b), LFA-3 (CD58), and intercellular adhesion molecule-1 (ICAM-1) (CD54) expression did not change with allergen stimulation. We also showed that CD49d receptor density on T cells obtained by bronchoalveolar lavage (BAL) of allergic patients before and 48 h after allergen challenge was significantly higher than that on T cells taken from BAL of normal subjects and from controls with other inflammatory lung diseases. Taken together, these findings indicate that allergen stimulation activates allergen-specific T cells and coordinately induces increased CD49d receptor expression and binding to counterligands. We postulate that allergen-driven upregulation of CD49d, which together with the beta1 chain constitutes VLA-4 integrin, may be responsible for the selective accumulation of T cells in the allergic asthmatic lung.

Increased IgE antiovalbumin level in mice exposed to formaldehyde

The effect of formaldehyde exposure on the sensitization of mice to ovalbumin was investigated. Significantly increased IgE antiovalbumin titers were found in mice sensitized intranasally to ovalbumin and exposed for 10 days to 2 mg/m3 of formaldehyde. In contrast, mice not exposed to formaldehyde or exposed once a week produced low levels of this antibody. The exposure of mice, sensitized intraperitoneally with ovalbumin, to formaldehyde did not increase sensitization. It was concluded that formaldehyde facilitates sensitization of mice to ovalbumin by changes that occur in the respiratory tract.

Neutrophil chemiluminescence following exposure to formaldehyde in healthy subjects and in patients with contact dermatitis

13 formaldehyde-sensitive contact dermatitis patients and 5 healthy subjects were exposed to formaldehyde (FM) at a concentration 0.5 mg/m3, in an exposure chamber for 2 hours. There was no significant decrease of the ventilatory parameters either in healthy subjects or in contact dermatitis patients following the exposure Bronchial hyperreactivity to histamine (PC20) increased in one healthy and two patients with contact dermatitis. Neutrophils were isolated from whole venous blood before the test and 30 minutes and 24 hours after the exposure. All subjects with allergic contact dermatitis had chemiluminescence higher before the FM provocation in a comparison with the healthy ones. It increased significantly 30 minutes post the exposure and was much higher 24 hours after the exposure in the comparison with the neutrophil chemiluminescence before the test.