POS0515 THE ASSOCIATION BETWEEN AUTOANTIBODIES AND RISK FOR VENOUS THROMBOEMBOLIC EVENTS AMONG PATIENTS WITH RHEUMATOID ARTHRITIS

Background

Patients with rheumatoid arthritis (RA) have an increased risk for cardiovascular disease, including venous thromboembolic events (VTE)1. The reason behind the increased VTE risk is incompletely understood, but inherent features of RA, such as RA specific autoantibodies, could potentially play a role. For example, studies have linked occurrence and levels of rheumatoid factor (RF) in the general population to increased VTE risk2. We and others have demonstrated an association between ACPA and risk of later ischemic cardiovascular events3. There are also potential mechanistic links; citrullinated fibrinogen (cFib) has been associated to clot stability4.

Objectives

We aimed to examine the association between anti-modified protein antibodies (AMPAs) and risk of VTE in RA.

Methods

We included 2809 individuals newly diagnosed with RA and included in the Swedish EIRA study 1996-2009. Through linkage to nationwide health care registers we identified past and incident events of VTE based on validated ICD code algorithms. We centrally typed baseline sera for anti-CCP2, 20 different ACPA sub-specificities, RF isotypes, carbamylated antibodies and 10 additional post-translational modifications. We followed all individuals from RA diagnosis up until their first ever VTE event, migration, death or end of study (2020-12-31) whichever occurred first. We used a Cox regression to estimate hazard ratios (HR) with 95% confidence intervals (CI). Individuals with a history of a VTE event (n=27) at RA diagnosis were excluded.

Results

We included 2782 individuals; 72% were women, median age at RA diagnosis was 54 years (inter quartile range (IQR) 18 years) and median follow-up time was 15.5 (IQR 6.8) years. During follow-up 177 incident VTE events were observed corresponding to an incidence of 5.0 per 1,000 person years.

1797 (64.6%) patients were positive for IgG anti-CCP2 and the HR for VTE (vs. being negative for anti-CCP2) was 1.33 (95%CI 1.00-1.78). The risk of VTE increased with the level of anti-CCP2, with an HR of 1.49 (95%CI 0.99-2.22) for the group with extreme levels compared to those negative for anti-CCP2 (p-value for trend 0.048). For IgA anti-CCP2 the HR was 1.35 (95% CI 0.99-1.84) when comparing those expressing IgA anti-CCP2 against those who did not.

Of 20 ACPA fine-specificities studied, 18 occurred with a frequency > 10% in our sample. The median number of fine-specificities expressed was 6 (IQR 11). The risk of VTE increased with the number of ACPA fine-specificities expressed (p-value for trend 0.033). At the 0.05 significance level, two fine-specificities were each associated with VTE; cPept Z1 [HR=1.40 (95%CI 1.06-84)] and cPept-1 [HR=1.47 (95%CI 1.12-1.93)]. None of the six antibodies against cFib assessed were statistically significantly associated with VTE risk. No associations were observed for other AMPAs. Among the three RF isotypes, only IgM RF was statistically associated with VTE [HR=1.38 (95%CI 1.04-1.83)].

Conclusion

RA-related antibodies analysed in clinical practice (anti-CCP2 IgG, RF) are associated not only with risk of myocardial infarction, stroke and cardiovascular death as previously demonstrated but also with VTE. There were no clear specific signals with ACPA fine-specificities, other AMPAs, or IgA RA autoantibodies.

References

[1]Holmqvist ME,et al. Risk of venous thromboembolism in patients with rheumatoid arthritis and association with disease duration and hospitalization. JAMA. 2012;308(13):1350-6.

[2]Meyer-Olesen CL, et al. Increased rheumatoid factor and deep venous thrombosis: 2 cohort studies of 54628 individuals from the general population. Clin Chem. 2015;61(2):349-59.

[3]Westerlind H, et al. Anti-citrullinated protein antibody specificities, rheumatoid factor isotypes and incident cardiovascular events in patients with rheumatoid arthritis. Arthritis Rheumatol. 2020.

[4]Maners J, et al. A Mendelian randomization of gamma’ and total fibrinogen levels in relation to venous thromboembolism and ischemic stroke. Blood. 2020;136(26):3062-9.

Disclosure of Interests

Helga Westerlind: None declared, Alf Kastbom: None declared, Johan Rönnelid: None declared, Monika Hansson: None declared, Lars Alfredsson: None declared, Linda Mathsson-Alm Employee of: LMA an employee of Thermo Fisher Scientific producing the ACPA sub-specificity test, Guy Serre: None declared, Martin Cornillet: None declared, Rikard Holmdahl Consultant of: historically several. Currently paid advisor for Lipum AB and Cyxone AB, Per-Johan Jakobsson Consultant of: UCB – Nov 2021 to Feb 2022., Karl Skriner: None declared, Holger Bang Employee of: HB is an employee of Orgentec Diagnostica, an IVRc company, Lars Klareskog: None declared, Saedis Saevarsdottir Employee of: SS is a part-time employee of deCODE genetics Inc., Karin Lundberg: None declared, Caroline Grönwall: None declared, Johan Askling Grant/research support from: AbbVie, AstraZeneca, Bristol Myers Squibb, Eli Lilly, Janssen, Merck, Pfizer, Roche, Samsung Bioepis, Sanofi, and UCB.

POS0009 THE RELATIONSHIP BETWEEN DIFFERENT IGG AND IGA ANTI-MODIFIED PROTEIN AUTOANTIBODIES IN RHEUMATOID ARTHRITIS

Background:

Seropositive rheumatoid arthritis (RA) is characterized by the presence of rheumatoid factor (RF) and anti-citrullinated protein autoantibodies (ACPA) with different fine-specificities. Yet, other serum anti-modified protein autoantibodies (AMPA), e.g. anti-carbamylated (Carb), anti-acetylated (KAc), and anti-malondialdehyde acetaldehyde (MAA) modified protein antibodies, have been described. By using RA patient single-cell derived monoclonal antibodies we have previously shown that individual ACPA clones recognize small distinct citrulline-containing epitopes giving them extensive multireactivity when these epitopes are found in many peptides and proteins. Moreover, certain CCP2+ multireactive ACPA clones bind also to cabamylated and acetylated autoantigens [1].

Objectives:

To provide a comprehensive evaluation of serum IgG and IgA autoreactivity to different post-translational modifications in RA.

Methods:

We analyzed 30 different IgG and IgA AMPA reactivities to modified antigens by ELISA and autoantigen arrays, in N=1985 newly diagnosed RA patients and population controls. The study utilized both previously established (i.e IgG and IgA CCP2; IgG ACPA fine-specificities; IgG anti-Carb fibrinogen and Carb FCS; IgG and IgA Cit/Carb/KAc/Orn(Ac)-vimentin), and novel assays (e.g. IgG anti-MAA and IgG anti-acetylated histones). Association with patient characteristics such as smoking and disease activity were explored. The newly developed assays were also evaluated in SLE disease controls and CCP2+ RA-risk individuals without arthritis.

Results:

Carb and KAc reactivities by different assays were primarily seen in patients also positive for citrulline-reactivity. Modified vimentin (mod-Vim) peptides were used for direct comparison of different AMPA reactivities, revealing that IgA AMPA recognizing mod-Vim was mainly detected in subsets of patients with high IgG anti-Cit-Vim levels and a history of smoking. IgG acetylation reactivity was mainly detected in a subset of patients with Cit and Carb reactivity. Anti-acetylated histone 2B reactivity was RA-specific and associated with high anti-CCP2 IgG levels, multiple ACPA fine-specificities, and smoking. This reactivity was also found to be present in CCP2+ RA-risk individuals without arthritis. Our data further demonstrate that IgG autoreactivity to MAA was increased in RA compared to controls with highest levels in CCP2+ RA, but was not RA-specific, and showed low correlation with other AMPA. Anti-MAA was instead associated with disease activity and was not significantly increased in CCP2+ individuals at risk of RA. Notably, RA patients could be subdivided into four different subsets based on their AMPA IgG and IgA reactivity profiles.

Conclusion:

We conclude that autoantibodies exhibiting different patterns of ACPA fine-specificities as well as Carb and KAc reactivity are present in RA and may be derived from multireactive B-cell clones. Anti-Carb and anti-KAc could be considered reactivities within the “Cit-umbrella” similar to ACPA fine-specificities, while MAA is distinctly different.

References:

[1]Sahlström P, Hansson M, Steen J, Amara K, Titcombe PJ, Forsström B, Stålesen R, Israelsson L, Piccoli L, Lundberg K, Klareskog L, Mueller DL, Catrina AI, Skriner K, Malmström V, Grönwall C. Different Hierarchies of Anti-Modified Protein Autoantibody Reactivities in Rheumatoid Arthritis. Arthritis Rheumatol. 2020 Oct;72(10):1643-1657. PMID: 32501655

Caroline Grönwall: None declared, Lisa Liljefors: None declared, Holger Bang Employee of: Employee at ORGENTEC Diagnostika GmbH, Aase Hensvold: None declared, Monika Hansson: None declared, Linda Mathsson-Alm Employee of: Employee at Thermo Fisher Scientific, Lena Israelsson: None declared, Anna Svärd: None declared, Cyril CLAVEL: None declared, Elisabet Svenungsson: None declared, Iva Gunnarsson: None declared, Guy Serre: None declared, Saedis Saevarsdottir: None declared, Alf Kastbom: None declared, Lars Alfredsson: None declared, Vivianne Malmström: None declared, Johan Rönnelid: None declared, Anca Catrina: None declared, Karin Lundberg: None declared, Lars Klareskog: None declared

POS1425 ANTIBODIES TO PORPHYROMONAS GINGIVALIS ASSOCIATE WITH THE PRESENCE OF RHEUMATOID ARTHRITIS-RELATED AUTOANTIBODIES IN PATIENTS WITH PERIODONTITIS

Background:

Epidemiologic studies have demonstrated a link between periodontitis (PD) and rheumatoid arthritis (RA), specifically RA characterized by anti-citrullinated protein antibodies (ACPA). The keystone pathogen driving PD, Porphyromonas gingivalis (Pg), is the only pathogen known to express peptidylarginine deiminase (PAD), a citrullinating enzyme. Hence, Pg has been proposed to be involved in triggering the ACPA response, by generating citrullinated antigens in an inflammatory milieu(1). Another major virulence factor of Pg is arginine gingipain B (RgpB), a proteinase which cleaves proteins so that P.PAD can access the site where citrullination takes place. We have previously shown elevated anti-RgpB IgG levels in ACPA+ RA patients, even before clinical onset(2, 3), and we hypothesize that anti-RgpB IgG could serve as a serological marker to identify PD patients with increased risk of developing ACPA+ RA.

Objectives:

Based on this hypothesis, we set out to investigate whether anti-RgpB IgG was associated with PD, PD severity, autoimmunity in general, and the ACPA response in particular.

Methods:

Anti-RgpB IgG, as well as RA- and systemic lupus erythematosus (SLE)-related autoantibodies targeting cyclic citrullinated peptide(s) (CCP2), rheumatoid factor (RF), dsDNA, cardiolipin, and β2 glycoprotein, were measured by ELISA in serum samples from the ParoKrank study, which is a well-characterized cohort of 805 patients with a first myocardial infarction and 805 matched controls, where periodontal status has been determined by dentists(4). In this study, individuals with PD (n=941) were compared to individuals without PD (n=557).

Results:

We detected significantly elevated (p<0,0001) anti-RgpB IgG levels in PD compared to non-PD individuals, with highest levels recorded in severe PD. Anti-RgpB IgG levels were significantly increased in PD patients positive for CCP2 and/or RF (n=50), when compared to PD patients negative for CCP2 and RF (n=507), p<0,05, and when compared to non-PD individuals positive for CCP2 and/or RF (n=62), p < 0,05. Notably, these differences were not seen for SLE-related autoantibodies. In addition, anti-RgpB IgG levels were significantly elevated amongst MI patients versus controls (p < 0,05), supporting the previous finding that PD is more common among MI patients(4).

Conclusion:

Our data demonstrates a specific association between severe PD, elevated anti-RgpB IgG levels and RA-related autoantibodies, supporting a role for Pg in linking PD to ACPA+ RA. Further investigation will be needed to confirm whether anti-RgpB IgG can be used as a serological marker to identify PD patients with increased risk of developing ACPA+ RA.

References:

[1]Rosenstein ED, Greenwald RA, Kushner LJ, Weissmann G. Hypothesis: the humoral immune response to oral bacteria provides a stimulus for the development of rheumatoid arthritis. Inflammation. 2004;28(6):311-8.

[2]Kharlamova N, Jiang X, Sherina N, Potempa B, Israelsson L, Quirke AM, et al. Antibodies to Porphyromonas gingivalis Indicate Interaction Between Oral Infection, Smoking, and Risk Genes in Rheumatoid Arthritis Etiology. Arthritis Rheumatol. 2016;68(3):604-13.

[3]Johansson L, Sherina N, Kharlamova N, Potempa B, Larsson B, Israelsson L, et al. Concentration of antibodies against Porphyromonas gingivalis is increased before the onset of symptoms of rheumatoid arthritis. Arthritis Res Ther. 2016;18(1):201.

[4]Rydén L, Buhlin K, Ekstrand E, Faire Ud, Gustafsson A, Holmer J, et al. Periodontitis Increases the Risk of a First Myocardial Infarction. Circulation. 2016;133(6):576-83.

Disclosure of Interests:

None declared

Retinal vascular diameters in relation to physical activity in Danish children - The CHAMPS Eye Study

Our objective was to determine associations between retinal vascular caliber and physical activity (PA) in a school-based child cohort. In a prospective study, we created a childhood cumulative average PA-index using objectively measured PA (accelerometry) assessed at four periods between 2009 and 2015. Cumulative exposure to PA intensities was estimated. Cross-sectional examinations on biomarkers, anthropometry, and ophthalmological data including retinal fundus photographs were performed in 2015. Semi-automated measurements of retinal vascular diameters were performed and summarized into central retinal arteriolar and venular equivalents (CRAE, CRVE). We included 307 participants. Mean age in 2015 was 15.4 years (0.7). The mean CRAE and CRVE were 156.5 μm (2.8) and 217.6 μm (7.7), respectively. After adjusting for age, gender, and axial length, more time in PA was independently related to thinner retinal venules (β-coefficient = -1.25 μm/%, 95% confidence interval = -2.20, -0.30, P < .01). Sedentary time was associated with wider venules (P < .01). Furthermore, birthweight (β-coefficient = 0.56 μm/%, 95% confidence interval = 0.18, 0.95, P < .01) was associated with CRVE. Blood pressure was associated with thinner retinal arterioles (β-coefficient = -0.19 μm/mmHg, 95% confidence interval = -0.36, -0.01, P = .04). We concluded that children with higher PA in childhood had thinner retinal venular caliber. Our results suggest that PA during childhood positively impacts the retinal microcirculation and that retinal vascular analysis may be a possible assessment to detect microvascular impairments in children with an increased risk of future cardiovascular disease.

Murine polyomavirus virus-like particles carrying full-length human PSA protect BALB/c mice from outgrowth of a PSA expressing tumor

Virus-like particles (VLPs) consist of capsid proteins from viruses and have been shown to be usable as carriers of protein and peptide antigens for immune therapy. In this study, we have produced and assayed murine polyomavirus (MPyV) VLPs carrying the entire human Prostate Specific Antigen (PSA) (PSA-MPyVLPs) for their potential use for immune therapy in a mouse model system. BALB/c mice immunized with PSA-MPyVLPs were only marginally protected against outgrowth of a PSA-expressing tumor. To improve protection, PSA-MPyVLPs were co-injected with adjuvant CpG, either alone or loaded onto murine dendritic cells (DCs). Immunization with PSA-MPyVLPs loaded onto DCs in the presence of CpG was shown to efficiently protect mice from tumor outgrowth. In addition, cellular and humoral immune responses after immunization were examined. PSA-specific CD4⁺ and CD8⁺ cells were demonstrated, but no PSA-specific IgG antibodies. Vaccination with DCs loaded with PSA-MPyVLPs induced an eight-fold lower titre of anti-VLP antibodies than vaccination with PSA-MPyVLPs alone. In conclusion, immunization of BALB/c mice with PSA-MPyVLPs, loaded onto DCs and co-injected with CpG, induces an efficient PSA-specific tumor protective immune response, including both CD4⁺ and CD8⁺ cells with a low induction of anti-VLP antibodies.

Tumor-specific bacteriophages induce tumor destruction through activation of tumor-associated macrophages

We recently reported that administration of tumor-specific bacteriophages initiates infiltration of neutrophilic granulocytes with subsequent regression of established B16 tumors. The aim of the current study was to investigate the mechanism of action of bacteriophage-induced tumor regression and to examine possible stimulatory effects of bacteriophages on macrophages. We observed that the mechanism of phage-induced tumor regression is TLR dependent as no signs of tumor destruction or neutrophil infiltration were observed in tumors in MyD88(-/-) mice in which TLR signaling is abolished. The microenvironment of bacteriophage-treated tumors was further analyzed by gene profiling through applying a low-density array preferentially designed to detect genes expressed by activated APCs, which demonstrated that the M2-polarized tumor microenvironment switched to a more M1-polarized milieu following phage treatment. Bacteriophage stimulation induced secretion of proinflammatory cytokines in both normal mouse macrophages and tumor-associated macrophages (TAMs) and increased expression of molecules involved in Ag presentation and costimulation. Furthermore, mouse neutrophils selectively migrated toward mediators secreted by bacteriophage-stimulated TAMs. Under these conditions, the neutrophils also exhibited increased cytotoxicity toward B16 mouse melanoma target cells. These results describe a close interplay of the innate immune system in which bacteriophages, located to the tumor microenvironment due to their specificity, stimulate TAMs to secrete factors that promote recruitment of neutrophils and potentiate neutrophil-mediated tumor destruction.

Multiple antibody reactivities to citrullinated antigens in sera from patients with rheumatoid arthritis: association with HLA-DRB1 alleles

BACKGROUND

Autoantibodies to cyclic citrullinated peptides (anti-CCP) are present in most patients with rheumatoid arthritis (RA), and associate with HLA-DRB1 shared epitope (SE) alleles.

OBJECTIVE

To investigate reactivities of anti-CCP to various citrullinated proteins/peptides, which represent potential autoantigens in RA, and to examine the relationship between such antibodies, and their association with genetic variants within HLA-DRB1 SE alleles.

METHODS

Serum samples from 291 patients with established RA and 100 sex- and age-matched healthy subjects were included in this study. Sera were first analysed for presence of anti-CCP antibodies and further for IgG and IgA antibodies towards candidate autoantigens in both their native and citrullinated form including: fibrinogen, alpha-enolase peptide-1 and the C1-epitope of type II collagen (C1(III)). Antibody specificity was confirmed by cross-reactivity tests. HLA-DR genotyping was performed.

RESULTS

72% of patients with RA were anti-CCP positive. Among the candidate autoantigens examined, IgG antibodies to citrullinated fibrinogen were found in 66% of patients' sera and in 41% for both citrullinated alpha-enolase peptide-1 and citrullinated C1(III). These antibodies were mainly seen in the anti-CCP-positive patient group; they were specific for their respective antigen and displayed limited cross reactivity. IgA responses were also detected, but less frequently than IgG. Anti-CCP and anti-citrullinated protein antibodies were associated with HLA-DRB1*04 rather than with HLA-DRB1*01 alleles.

CONCLUSIONS

Antibodies directed against several citrullinated antigens are present in CCP-positive RA, with many patients displaying multireactivity. All specific reactivities were primarily associated with the HLA-DRB1*04 alleles, suggesting common pathways of anti-citrulline immunity.

Citrullinated Proteins in Arthritis; their Presence in Joints and Effects on Immunogenicity

Autoantibodies directed against citrulline‐containing proteins have an impressive specificity of nearly 100% in RA patients and a suggestive involvement in the pathogenesis. The targeted epitopes are generated by a post‐translational modification catalysed by the calcium‐dependent enzyme peptidyl arginine deaminase that converts the positively charged arginine to polar but uncharged citrullin. The aim of this study was to analyse the presence of citrulline in the joints at different time points of collagen‐induced arthritis in DA rats by immunohistochemistry and to investigate how immunogenicity and arthritogenicity was affected by citrullination of rat serum albumin (RSA) and collagen type II (CII). Our results indicate that citrulline could be detected in joints of arthritic animals, first appearance at the onset of disease and increasing as disease progressed into a chronic state. Unimmunized animals or time points before clinical signs of arthritis were negative. By morphology, we state that some infiltrating macrophages as well as the cartilage surface stain positive for citrulline, while the major source of citrullinated proteins appears to be fibrin depositions. A specific Cit‐RSA T‐cell response was observed in animals challenged by citrullinated RSA, no response was recorded when RSA was used as a stimulus. The IgG analysis reveals not only a response towards the modified protein but also cross‐reactivity to native RSA. No T‐cell or B‐cell response was noted in animals injected with unmodified RSA. Cit‐CII induced a disease with higher incidence and earlier onset than did the native counterpart. We conclude that, in contrast to the human disease, citrulline does not seem to appear before clinical signs. As inflammation proceeds, citrulline is detected specifically in the joints. All other organs investigated were negative. We also conclude that citrullination of a protein can break tolerance and increase its arthritogenic properties.

CD4+CD25high T cells are enriched in the tumor and peripheral blood of prostate cancer patients

In this study, we investigated whether CD4+CD25high regulatory T cells (Treg) are increased in the tumor tissue and peripheral blood of early-stage prostate cancer patients undergoing prostatectomy. We show that the prevalence of CD4+CD25high T cells inside the prostate was significantly higher in the tumor compared with benign tissue from the same prostate. Furthermore, the frequency of CD4+CD25high T cells in peripheral blood was significantly higher in prostate cancer patients compared with normal donors. A proportion of the CD4+CD25high T cells was also shown to be glucocorticoid-induced TNF receptor, ICOS, and FOXP3 positive. Moreover, CD4+CD25+ T cells from blood and supernatants from cultured prostate tumor tissue samples exhibited immunosuppressive function in vitro. Furthermore, supernatants from cultured prostate tissue samples and prostate cancer ascites fluid induced migration of CD4+CD25+ T cells and were shown to contain the regulatory T cell chemokine CCL22 by ELISA. Our findings indicate that Tregs are an important cellular component of early-stage prostate tumors, and thus new therapeutic strategies aimed at inhibition or depletion of Tregs may improve prostate cancer immunotherapy.

CD4+CD25high T cells are enriched in the tumor and peripheral blood of prostate cancer patients

In this study, we investigated whether CD4+CD25high regulatory T cells (Treg) are increased in the tumor tissue and peripheral blood of early-stage prostate cancer patients undergoing prostatectomy. We show that the prevalence of CD4+CD25high T cells inside the prostate was significantly higher in the tumor compared with benign tissue from the same prostate. Furthermore, the frequency of CD4+CD25high T cells in peripheral blood was significantly higher in prostate cancer patients compared with normal donors. A proportion of the CD4+CD25high T cells was also shown to be glucocorticoid-induced TNF receptor, ICOS, and FOXP3 positive. Moreover, CD4+CD25+ T cells from blood and supernatants from cultured prostate tumor tissue samples exhibited immunosuppressive function in vitro. Furthermore, supernatants from cultured prostate tissue samples and prostate cancer ascites fluid induced migration of CD4+CD25+ T cells and were shown to contain the regulatory T cell chemokine CCL22 by ELISA. Our findings indicate that Tregs are an important cellular component of early-stage prostate tumors, and thus new therapeutic strategies aimed at inhibition or depletion of Tregs may improve prostate cancer immunotherapy.

Arthritogenicity of collagen type II is increased by chlorination

During inflammation, activated neutrophils, monocytes and macrophages produce and release myeloperoxidase (MPO). MPO converts hydrogen peroxide to hypochlorous acid, a highly reactive and oxidizing agent. Proteins subjected to hypochlorous acid become chlorinated. We analysed how chlorination of the cartilage antigen collagen type II (CII) affects its immunogenic and arthritogenic properties by studying immune responses to chlorinated CII in comparison to immune responses to CII and by studying the development of arthritis in rats immunized with CII-Cl. CII-Cl immunization of LEW.1AV1 rats caused a 100% incidence of arthritis with a mean maximum score of 9.2 (maximal score possible 16). The same dose of non-chlorinated CII did not induce arthritis at all. Rats immunized with CII-Cl developed high anti-CII-Cl IgG titres and also developed IgG antibodies recognizing the non-chlorinated form of CII. Analysis of cytokine mRNA expression in lymph nodes 10 days after immunzation revealed an increased expression of interferon (IFN)-gamma mRNA and interleukin (IL)-1beta mRNA in CII-Cl-immunized rats compared to CII-immunized rats. Thus, chlorination of CII increased its immunogenicity as well as its arthritogenicity. As neutrophils, monocytes and macrophages are abundant cells in arthritic joints of patients with rheumatoid arthritis, chlorination might be a mechanism by which immunoreactivity to CII is induced and by which chronic joint inflammation is supported.

Inhibition by Artocarpus tonkinensis of the Development of Collagen-Induced Arthritis in Rats

Extracts of the leaves and roots from the tree Artocarpus tonkinensis A Cheval (family Moraceae) are used in traditional Vietnamese medicine in order to treat backache as well as rheumatic joint diseases. We prepared an ethyl acetate (EtOAc) extract from this plant and tested its anti-inflammatory properties in an experimental arthritis model, collagen-induced arthritis (CIA). CIA was induced in Dark Agouti rats by means of immunization with collagen type II (CII) emulsified in incomplete Freund's adjuvant. Starting at the day of immunization, the rats were treated daily with intraperitoneal injections of Artocarpus extract. Arthritis progression was measured by means of clinical scoring of paws and anti-CII antibody titres were measured by means of ELISA. In vitro, lymph node (LN) cell cultures were treated with Artocarpus extract and the apoptosis-inducing effect was determined with FACS staining by using annexin V and propidium iodide as well as the TUNEL method. Treatment of the rats with Artocarpus extract decreased arthritis incidence and severity and delayed disease onset. When treatment was started after the onset of arthritis, a tendency towards arthritis amelioration was observed. In vitro, Artocarpus extract acted as a T-cell modulator, inhibiting mitogen-induced T-cell proliferation and inducing apoptosis of activated LN-derived lymphocytes. Thus, we have demonstrated that an EtOAc extract of Artocarpus, a plant traditionally used in Vietnamese folk medicine for treating arthritic conditions, has beneficial effects in an experimental arthritis model. This effect is likely to be T cell-dependent and mediated through apoptosis induction in activated cells.

Antigen inhibition of collagen-induced arthritis is associated with up-regulation of IL-4 mRNA and induction of Ox40 on T cells in draining lymph nodes

The addition of a foreign antigen to an inoculum completely inhibits the development of collagen-induced arthritis (CIA). However, the mechanism of this phenomenon, antigen -inhibition, is incompletely understood. Previous studies have demonstrated that the inhibition of arthritis is not mediated through suppression of the antibody response to cartilage antigens. In this paper we investigated cytokine mRNA levels in lymph nodes cells recovered 3, 7 or 16 days from animals immunized with either collagen II in IFA or OVA + collagen II in IFA. At day 7, but not at other time-points, IL-4 mRNA was up-regulated in the lymph nodes of OVA-inhibited non-arthritic animals compared to control animals which all developed arthritis. No significant differences between the two groups could be detected when expression of IFN-gamma, IL-2, TNF-alpha, IL-1beta or IL-10 mRNA was analysed. Flow cytometry analysis of draining lymph node cells demonstrated that the T cell marker Ox40 was up-regulated in the OVA-inhibited group. Our results indicate that the complete inhibition of CIA caused by addition of OVA to the collagen II inoculum is due to the presence of a TH2 environment resulting from an increased production of IL-4 mRNA and a parallel increase in Ox40+ T cells.

Immune-specific up-regulation of adseverin gene expression by 2,3,7,8-tetrachlorodibenzo-p-dioxin

To identify genes that are regulated by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and possibly involved in TCDD-induced immunotoxicity, we used the differential display technique to screen for differentially expressed genes in the mouse thymus. Here we show that TCDD increased the expression of adseverin, a Ca(2+)-dependent, actin-severing protein. The induction of adseverin is dose- and time-dependent in parallel with the induction of CYP1A1, which is currently the most frequently used marker for TCDD exposure. A comparison between mouse strains with different TCDD responsiveness indicated that the induction of adseverin is dependent on the aryl hydrocarbon receptor, a transcription factor known to mediate most of TCDD's biological effects. Examination of additional organs revealed that the up-regulation of the adseverin gene expression is immune-specific. Using an anti-adseverin antibody, we confirmed the induction of adseverin by TCDD at the protein level and it was confined to the thymic cortex, which harbors immature thymocytes that are known target cells of TCDD. Considering adseverin's role in actin cytoskeletal reorganization, our observations reveal new mechanistic aspects of how TCDD might exert some of its immunotoxic effects.

Clinical results of phacoemulsification with the use of Healon5 or Viscoat

PURPOSE

To compare the ophthalmic viscosurgical devices Healon5 (viscoadaptive) and Viscoat (dispersive) regarding their overall clinical performance during phacoemulsification and posterior chamber intraocular lens (IOL) implantation as well as their influence on intraocular pressure (IOP).

SETTING

Department of Ophthalmology, Ruprecht-Karls-University Heidelberg, Heidelberg, Germany.

METHODS

In this prospective randomized patient- and observer-masked clinical study, the performance of Healon5 (sodium hyaluronate 2.3%) and Viscoat (sodium hyaluronate 3.0%-chondroitin sulfate 4.0%) was assessed by 3 surgeons during cataract surgery in 90 patients. Surgeons used a 5-point scale for the subjective assessment of the ease of injection, maintenance capacity during continuous curvilinear capsulorhexis, remaining capacity during phacoemulsification, facilitation of IOL implantation, removal from the eye, transparency, and overall performance throughout surgery. Intraocular pressure was measured preoperatively and 24 hours and 7 days postoperatively. Best corrected visual acuity was assessed preoperatively and 7 days postoperatively.

RESULTS

Overall intraoperative product performance was assessed as good or very good in 34 of 44 patients (77%) in the Healon5 group and in 16 of 46 patients (35%) in the Viscoat group (P <.001). Retention in the anterior chamber was graded good or very good in 36 patients (82%) in the Healon5 group and in 23 (50%) in the Viscoat group (P =.001). There were no statistically significant between-group differences in mean IOP preoperatively and 24 hours postoperatively.

CONCLUSIONS

Surgeons graded Healon5 better than Viscoat in overall surgical performance and retention in the anterior chamber during phacoemulsification. These data support that Healon5 adapts to each step during surgery.

Specificity and function of "natural" antibodies in immunodeficient subjects: clues to B cell lineage and development

The origin of natural antibodies has long been a subject of controversy. Polyreactive natural antibodies recognize multiple ligands and are thought to arise from B1 B cells. Natural antibodies against carbohydrate antigens such as Gal alpha 1-3Gal or against blood groups A and B are thought to be "elicited" by gut bacteria, but their origin is uncertain. To explore the origin of naturally occurring anticarbohydrate antibodies, the specificity and function of the xenoreactive antibodies and isohemagglutinins were investigated in immunodeficient subjects. Subjects with defects in T cell-dependent antibody synthesis had normal levels of xenoreactive natural antibodies, most of which, like xenoreactive antibodies from normal individuals, were specific for Gal alpha 1-3Gal. On the other hand, some subjects with hyper-IgM syndrome who were able to synthesize abundant quantities of xenoreactive antibodies and polyreactive antibodies were devoid of anti-Gal alpha 1-3Gal antibodies. These results suggest that the lineages of B cells giving rise to anti-Gal alpha 1-3Gal antibodies and isohemagglutinins are distinct from B1 B cells or at least exist at a more "advanced" stage of development than those B1 B cells that give rise to polyreactive antibodies. The findings also suggest that B cells which synthesize anti-Gal alpha 1-3Gal antibodies and isohemagglutinins may be distinct from B2 B cells or exist at a more "primitive" stage of development than B2 B cells that synthesize elicited antibodies in normal individuals.

Effect of Diclofenac on Prostaglandin Liberation in the Rabbit after Photorefractive Keratectomy

BACKGROUND

An analyses of the concentration of arachidonic acid metabolites and the infiltration of leukocytes in the aqueous humour of rabbits after excimer laser keratectomy was performed. The ability of topical diclofenac to block prostaglandin E2 liberation into the aqueous humour was also investigated.

METHODS

Photorefractive keratectomy was performed on both eyes of 60 New Zealand rabbits. Prostaglandin E2, 6-keto prostaglandin F1 alpha and thromboxane B2 were detected by radioimmunoassay and leukocytes were counted in the aqueous humour for 120 hours postoperatively. Topical diclofenac was instilled (1 drop/4h) in six animals and prostaglandin E2 was analyzed in the aqueous humour 16 hours postoperatively.

RESULTS

The prostaglandin E2 concentration in the aqueous humour increased from 13 in control animals, to 251 pg/100 microliters at 16 hours after treatment (p < 0.05). A statistically significant elevation in the aqueous concentration of 6-keto prostaglandin F1 alpha could not be demonstrated. Thromboxane B2 and leukocytes could not be detected at any time point. Topical diclofenac (1 drop/4h) reduced the levels of prostaglandin E2 in the aqueous humour below 10 pg/100 microliters, 16 hours postoperatively.

CONCLUSION

Topical diclofenac (1 drop/4h) inhibited prostaglandin E2 release into the aqueous humour.

Intermediate steps in thymic positive selection. Generation of CD4-8+ T cells in culture from CD4+8+, CD4int8+, and CD4+8int thymocytes with up-regulated levels of TCR-CD3

Minor thymus subpopulations representing possible intermediates in thymic positive selection were isolated by cell sorting from bcl-2 transgenic mice, and cultured 1 to 4 days in simple medium to assess their ability to spontaneously develop the surface phenotype of mature T cells. Recovery of cells was in the 60 to 80% range, and no cell proliferation occurred. Only cells originally expressing high, near mature T cell levels of CD3 developed further in culture by down-regulation of CD4 or CD8. The main mature cell product was CD4-8+, regardless of whether the starting phenotype of the CD3high intermediates was CD4+8+, CD4int8+, or CD4+8int; only an intermediate subpopulation expressing the highest levels of CD4 (CD4high8int) produced a dominance of CD4+8- mature progeny. Partial down-regulation of CD8 was therefore not a good indicator of CD4+ T lineage commitment. These and previous results indicate that maturation to the CD8+ T lineage involves a rapid up-regulation of the TCR-CD3 complex, but a relatively slow down-regulation of CD4; it may also involve a partial, transient reduction in surface CD8. In contrast, maturation to the CD4+ T lineage involves a relatively rapid down-regulation of CD8, with maintenance of high levels of CD4. There appears to be a marked asymmetry in the developmental steps leading from CD4+8+ thymocytes to the CD8+ or to the CD4+ T cell lineage.

Intermediate steps in thymic positive selection. Generation of CD4-8+ T cells in culture from CD4+8+, CD4int8+, and CD4+8int thymocytes with up-regulated levels of TCR-CD3

Minor thymus subpopulations representing possible intermediates in thymic positive selection were isolated by cell sorting from bcl-2 transgenic mice, and cultured 1 to 4 days in simple medium to assess their ability to spontaneously develop the surface phenotype of mature T cells. Recovery of cells was in the 60 to 80% range, and no cell proliferation occurred. Only cells originally expressing high, near mature T cell levels of CD3 developed further in culture by down-regulation of CD4 or CD8. The main mature cell product was CD4-8+, regardless of whether the starting phenotype of the CD3high intermediates was CD4+8+, CD4int8+, or CD4+8int; only an intermediate subpopulation expressing the highest levels of CD4 (CD4high8int) produced a dominance of CD4+8- mature progeny. Partial down-regulation of CD8 was therefore not a good indicator of CD4+ T lineage commitment. These and previous results indicate that maturation to the CD8+ T lineage involves a rapid up-regulation of the TCR-CD3 complex, but a relatively slow down-regulation of CD4; it may also involve a partial, transient reduction in surface CD8. In contrast, maturation to the CD4+ T lineage involves a relatively rapid down-regulation of CD8, with maintenance of high levels of CD4. There appears to be a marked asymmetry in the developmental steps leading from CD4+8+ thymocytes to the CD8+ or to the CD4+ T cell lineage.

Intermediate steps in positive selection: differentiation of CD4+8int TCRint thymocytes into CD4-8+TCRhi thymocytes

The differentiation potential of putative intermediates between CD4+8+ thymocytes and mature T cells has been examined. Such intermediate populations were sorted, in parallel with CD4+8+ thymocytes, from three types of C57BL/6 mice: major histocompatibility complex (MHC) class II-deficient mice, mice transgenic for an alpha/beta T cell receptor (TCR) restricted by class I MHC and normal mice. The sorted populations were then transferred into the thymus of nonirradiated C57BL/Ka mice differing in Thy 1 allotype, and the progeny of the transferred cells were analyzed 2 d later. Surprisingly, with all three types of donor mice, a major proportion of the CD4+8intTCRint-derived progeny were found to be CD4-8+TCRhi cells, thus delineating a new alternative pathway for development of the CD8 lineage. In contrast, the transfer of CD4int8+TCRint thymocytes produced CD4-8+TCRhi cells but no significant proportion of CD4+8-TCRhi cells, suggesting that there is no equivalent alternative pathway for the CD4 lineage. The results negate some of the evidence for a stochastic/selective model of lineage commitment, and point to an asymmetry in the steps leading to CD4-8+ versus CD4+8- T cells.

Omeprazole or ranitidine in long-term treatment of reflux esophagitis. The Scandinavian Clinics for United Research Group

BACKGROUND/AIMS

Patients with reflux esophagitis have rapid relapses after treatment withdrawal. This study was designed to investigate the relapse rate of symptomatic esophagitis during maintenance treatment with omeprazole or ranitidine.

METHODS

Patients with endoscopically verified acute erosive or ulcerative esophagitis were initially treated with 20-40 mg omeprazole daily for 8-12 weeks. After healing, the patients were randomized to maintenance treatment with omeprazole (20 or 10 mg each morning) or ranitidine (150 mg twice daily). Control endoscopy was performed at the end of the healing phase and after 12 months of maintenance treatment or symptomatic relapse.

RESULTS

Of 426 initially treated patients, 392 were healed and entered the maintenance study. The months of maintenance treatment with 20 mg omeprazole once daily (n = 131), 10 mg omeprazole once daily (n = 133), and 150 mg ranitidine twice daily (n = 128) were 72%, 62%, and 45%, respectively. Both the 10- and 20-mg doses of omeprazole were significantly better than the dose of ranitidine (P < 0.001 and P < 0.005, respectively). There was no significant difference between the 10- and 20-mg doses of omeprazole (P = 0.06).

CONCLUSIONS

Maintenance treatment with omeprazole (20 or 10 mg once daily) is superior to ranitidine (150 mg twice daily) in keeping patients with erosive reflux esophagitis in remission over a 12-month period.

Mercury levels in the hair of pregnant women in a polluted area in Sweden

Total mercury concentration in hair, sampled at delivery, was determined in women living in an area polluted with atmospheric emissions of mercury from a metal smelter, (n = 122) and in a control area (n = 75). Information on fish consumption was obtained at the 10th week of pregnancy. The average mercury concentration in hair was 0.27 mg/kg (range 0.07-0.96 mg/kg), which is somewhat lower than previously reported for pregnant women in Sweden and very low compared with levels in fish-eating populations in other parts of the world. Women living in the polluted area had significantly lower mercury levels in hair than women in the control area when comparing groups with quantitatively similar consumption of freshwater fish. Possibly, the population in the smelter area does not catch fish in the neighbourhood and/or the fish in the control area has elevated mercury levels. Consumption of freshwater fish > or = once a week resulted in approximately twice as high hair mercury levels as in those who did not eat freshwater fish at all. Also consumption of saltwater fish > or = once a week resulted in significantly higher hair mercury levels than in those consuming saltwater fish < once a month. Hair levels from the 10th week of pregnancy were similar to the levels at delivery in women with high (> or = once a week) consumption of freshwater fish but decreased during this period in women who did not eat freshwater fish at all, which could be explained by decreased exposure during pregnancy and measurement in recently formed hair.

Small cortical thymocytes are subject to positive selection

To determine the developmental stages at which positive selection can act to produce mature T cells, CD4+8+3lo thymocytes of large dividing type and of small nondividing type were sorted and transferred into the thymus of nonirradiated Thy-1 congenic recipient mice. In contrast to earlier studies, the small as well as the large thymocytes produced mature CD4+8-3hi and CD4-8+3hi progeny, although production was less efficient from the small cells. The relative efficiency of small cells was increased and was close to that of large cells when bcl-2/anti-HY T cell receptor (TCR) alpha beta transgenic donors were used to improve cell survival, overcome stress effects of the transfer process, and increase the frequency of selectable cells. The results from transferring small CD4+8+3lo thymocytes expressing a TCR transgene from a nonselecting to a selecting thymic MHC environment also confirmed that the small cells were capable of being selected and maturing. Thus the developmental window available for positive selection includes the small CD4+8+3lo thymocytes. The results also showed a striking difference in the kinetics of production of mature progeny from the transferred CD4+8+3lo precursors. CD4+8-3hi cells appeared several days before CD4-8+3hi cells, apparently because the CD4-8+ lineage cells spent several days in transit as CD4+8+3hi intermediates before losing CD4. Most CD4+8- lineage cells on the other hand, either passed very rapidly through this intermediate stage, or lost CD8 before increasing the expression of CD3.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) inhibits the activation of antigen-specific T-cells in mice

There are conflicting data in the literature regarding target cells in 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced immunotoxicity. In the present study, adult male C57BL/6 mice were exposed to TCDD (50 micrograms/kg) 4 days prior to immunization with ovalbumin (OVA). The effect of TCDD on the specific immune response in vivo was determined by T-cell proliferation and IL-2 production in response to either OVA or anti-mouse-CD3 antibodies plus PMA in vitro. The antigen-specific T-cell proliferation and IL-2 production in response to OVA were significantly suppressed by TCDD, while the polyclonal response to anti-CD3 antibodies plus PMA was not affected. This indicates that even at a high dose of TCDD the intra T-cell signalling pathways in resting cells are not disturbed, but TCDD selectively impairs the antigen-specific activation of T-cells. Since activated T-cells are required in antibody responses to T-dependent antigens, the low number of such cells observed in the present study, may well explain the suppressive effects of TCDD on humoral immunity reported previously.

Effects of a technical PCB preparation and fractions thereof on ethoxyresorufin O-deethylase activity, vitamin A levels and thymic development in the mink (Mustela vison)

Clophen A50, a technical preparation of polychlorinated biphenyls (PCBs), was separated into four fractions; three containing chlorobiphenyls with 0, 1, or 2 to 4 ortho chlorines and one containing di- and tricyclic impurities such as naphthalenes and dibenzofurans. Clophen A50, the four fractions, and a synthetic mixture of the biologically most active non-ortho-chlorinated congeners (3,3',4,4'-tetra-, 3,3',4,4',5-penta-, and 3,3',4,4',5,5'-hexachlorobiphenyl), were separately mixed in the feed and given to female mink during the reproductive season. The concentration of a given compound in the feed mixture was equivalent to its concentration in the feed mixed with Clophen A50. Hepatic 7-ethoxyresorufin O-deethylase (EROD) activity in adults was enhanced 2-3 times by Clophen A50, the fractions containing non- or mono-ortho-chlorinated congeners, and the synthetic mixture. In neonatal kits delivered by females treated with non- or mono-ortho-chlorinated congeners, EROD was enhanced to about 30 times the control value. No live kits were delivered by the females treated with unfractionated Clophen A50. The fractions containing congeners with two to four ortho chlorines or di- and tricyclic compounds did not significantly induce EROD in either adults or kits. Clophen A50 reduced hepatic and pulmonary vitamin A contents in adult mink, while renal vitamin A was unaffected. Responses to the fractions containing the non- and mono-ortho-chlorinated congeners were similar to those obtained with Clophen A50. Their effects were, however, less pronounced, particularly with respect to the hepatic vitamin A reduction. The fractions containing congeners with two to four ortho chlorines and the di- and tricyclic compounds had no significant effects on tissue vitamin A contents.(ABSTRACT TRUNCATED AT 250 WORDS)

Dexamethasone and 2,3,7,8-tetrachlorodibenzo-p-dioxin can induce thymic atrophy by different mechanisms in mice

The effects of in vivo exposure to dexamethasone (DEX) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on thymocyte proliferation and thymocyte number were compared. In the thymus of DEX-treated mice (1 mg/kg) both proliferation and cell number had decreased by 70% one day after exposure. This decrease was, however, transient, and values returned to normal within 2 weeks. By contrast, in TCDD exposed mice (50 micrograms/kg), a reduction in proliferation was not observed until day 2 after exposure, and the degree of reduction was only about 50%. By this point in time, cell number had only decreased by 20%. Proliferation increased again on day 3 after TCDD administration, whereas cell number continued to decrease and remained low throughout the observation period (8 days). DEX had a direct and immediate effect on cells in all thymocyte subpopulations whereas TCDD initially only affected the immature double negative (DN) and double positive (DP) populations.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) induced suppression of the local immune response

TCDD suppressed the normal immune response in popliteal and inguinal lymph nodes, when administered i.p. (50 micrograms/kg) to C57BL/6 mice, 4 days before immunization with the T-dependent antigen ovalbumin (10 micrograms/pad) in the hind foot pads. A hampered increase in lymph node cell number and a reduced frequency of antigen-specific B-cells were observed, despite the fact that cell proliferation in vivo was normal. While the restimulation of lymph node cells in vitro with ConA or LPS was normal, suggesting that the APC function was largely unaffected, the OVA-induced proliferation was greatly reduced. The anti-OVA antibody (ab) concentration both in serum and in supernatants of cultured lymph node cells was lower than in controls. In contrast, the production of anti-BSA ab upon LPS stimulation was normal. This indicates that the ability of the B-cells to produce ab and to proliferate was not disturbed. The DTH assay clearly showed an impaired T-cell function in TCDD-treated animals. Since APC or B-cells have appeared normal in their functions tested in this study, we propose that TCDD disturbed T-cell functions, leading to an impaired activation of B-cells.

Accumulation of hyaluronan in bronchoalveolar lavage fluid is independent of iron-, complement- and granulocyte-depletion in bleomycin-induced alveolitis in the rat

Previous studies on bleomycin-induced alveolitis in rats have demonstrated a transient histological accumulation of hyaluronan (hyaluronate or hyaluronic acid) in the alveolar interstitium, corresponding to increases in hyaluronan (HA) levels in bronchoalveolar lavage (BAL) fluid and lung tissue extracts. The accumulation of HA was related to the influx of inflammatory cells, especially polymorphonucleated cells (PMNs) in BAL fluid and the increase in lung water. In this study we have investigated the influence of iron, complement and PMN dependent mechanisms on the early connective response of the lung in the bleomycin rat model. Iron depletion had no effect on HA or the cellular composition of lavage fluid recovered on day 4 post bleomycin. Treatment of bleomycin-injured rats with cobra venom factor (CVF), totally neutralized complement haemolytic activity but had no effect on lavage HA or the cell invasion in BAL. Treatment with anti-neutrophil serum (ANS), reduced blood and lavage PMN by 70-80%, but had no influence on HA levels in BAL. These results suggest that regulatory mechanisms other than those dependent on iron, complement activation or PMN recruitment are responsible for HA accumulation in this fibrosing alveolitis animal model.

Accumulation of hyaluronan in bronchoalveolar lavage fluid is independent of iron-, complement- and granulocyte-depletion in bleomycin-induced alveolitis in the rat

Previous studies on bleomycin-induced alveolitis in rats have demonstrated a transient histological accumulation of hyaluronan (hyaluronate or hyaluronic acid) in the alveolar interstitium, corresponding to increases in hyaluronan (HA) levels in bronchoalveolar lavage (BAL) fluid and lung tissue extracts. The accumulation of HA was related to the influx of inflammatory cells, especially polymorphonucleated cells (PMNs) in BAL fluid and the increase in lung water. In this study we have investigated the influence of iron, complement and PMN dependent mechanisms on the early connective response of the lung in the bleomycin rat model. Iron depletion had no effect on HA or the cellular composition of lavage fluid recovered on day 4 post bleomycin. Treatment of bleomycin-injured rats with cobra venom factor (CVF), totally neutralized complement haemolytic activity but had no effect on lavage HA or the cell invasion in BAL. Treatment with anti-neutrophil serum (ANS), reduced blood and lavage PMN by 70-80%, but had no influence on HA levels in BAL. These results suggest that regulatory mechanisms other than those dependent on iron, complement activation or PMN recruitment are responsible for HA accumulation in this fibrosing alveolitis animal model.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) alters intrathymic T-cell development in mice

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) was administered to 2-4-week-old mice (5, 25, and 50 micrograms/kg body wt.) and to in vitro cultures (10(-9) M) of fetal thymi. By monitoring thymocyte populations with respect to the differentiation antigens CD4 and CD8, it was found that the cell number in all thymocyte populations except for CD8+ decreased significantly compared with controls. In vivo the most marked decrease occurred among double negative (DN) and double positive (DP) cells, whereas in vitro, the DP cells were most severely affected. The cell number had already decreased to some extent by day 1 after a dose of 50 micrograms/kg body wt. of TCDD, although a severe reduction did not become apparent until day 4. There was a clear dose/response relationship between 5 and 50 micrograms/kg body wt. Autoradiography and liquid scintillation counting studies showed that incorporation of [3H]thymidine in the thymus had already decreased 24 h after TCDD treatment, with the decrease being even more pronounced at 48 h. By 96 h, the rate of cell proliferation had returned to approximately normal values. The results show that TCDD has a long-lasting effect on thymocyte abundance together with a transient effect on cell proliferation. This indicates that in addition to the initial effects of TCDD on cell proliferation, it may also more permanently disturb the normal process of elimination by means of selection.

Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) treatment in vivo on thymocyte functions in mice after activation in vitro

Thymocytes from 15-day old C57BL/6 mice, pretreated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) 4 days before sacrifice, showed an earlier response and a higher maximal cell proliferation than thymocytes from control mice upon stimulation by concanavalin A in vitro. This is partly in contrast to the conclusions from earlier published studies. IL-2 content--as measured by growth of CTLL cells--was equally high in TCDD and in control cultures at day 1. At day 2, TCDD cultures had decreased dramatically in IL-2 content, possibly due to a high rate of consumption. At this point in time, the controls still contained a high concentration of IL-2, although less than at day 1. In contrast to the increased sensitivity to mitogen stimulation, thymocytes from TCDD-treated mice induced B-cells less avidly with respect to antibody production, and could also inhibit the T-cell help of thymocytes from untreated animals, a phenomenon which could be reversed if TCDD-treated thymocytes were irradiated before culture.

On the presence of the chromosomal proteins HMG I and HMG Y in rat organs

Using antiserum raised against HMG I, we have shown that HMG I and HMG Y are present in perchloric acid extracts of kidney, lung, heart, brain, liver and intestine in the rat, suggesting that the expression of these proteins may not be dependent upon proliferative activity. The results also show that the ratio between HMG I and HMG Y varies between different organs.

A monoclonal antibody to the membrane glycoprotein complex CD18 inhibits polymorphonuclear leukocyte accumulation and plasma leakage in vivo

Previous in vitro findings suggest a critical role for the polymorphonuclear leukocyte (PMN) membrane glycoprotein complex CD18 in PMN adherence and chemotaxis. We examined the effect of the murine monoclonal antibody (MoAb) 60.3, recognizing CD18, on induced PMN accumulation in vivo. Rabbits were pretreated with MoAb 60.3, and the chemotactic factors fMLP, leukotriene (LT)B4, and C5a, as well as histamine, were injected intradermally; 4 hours later, plasma leakage (125I-albumin) and the PMN accumulation (myeloperoxidase) were determined. Both PMN accumulation and PMN-dependent plasma leakage were abolished in the inflammatory skin lesions of rabbits pretreated with MoAb 60.3 as compared with control animals, whereas histamine-induced PMN-independent plasma leakage was unaffected. Intravital microscopy of the rabbit tenuissimus muscle revealed that MoAb 60.3 inhibited both PMN adherence in the venules and migration into the tissue following application of LTB4 and zymosan-activated serum (ZAS). Rolling of PMNs along the venular endothelium was unaffected. Thus, these experiments confirm and extend earlier in vitro findings of the critical role of the membrane glycoprotein complex, CD18, in PMN adherence and chemotaxis.

Effect of carotid artery occlusion and ganglionic blockade on regional blood flows and intestinal damage after haemorrhagic hypotension in the rat

The effects of cerebral ischaemia by carotid artery occlusion and of a ganglionic blocking agent (Arfonad) on cardiac output and regional blood flows were studied after 15 min of haemorrhagic hypotension (mean arterial pressure 50 mmHg) in the rat. The microsphere technique was used for blood flow determinations. Animals subjected to haemorrhagic hypotension and simultaneous carotid artery occlusion (group BC) exhibited a stronger immediate vasoconstrictor response than animals subjected to haemorrhagic hypotension only (group B) and more blood had to be withdrawn to achieve stable hypotension at 50 mmHg (2.6 +/- 0.1 vs. 2.2 +/- 0.4 ml per 100 g body weight (body wt); P less than 0.05). However, group B showed the same decrease in cardiac output as group BC, but the blood flows of the kidneys, spleen, intestine, liver and skin were less deranged at the end of the hypotensive period. Groups B and BC exhibited similar intestinal ischaemic mucosal damage, measured as leakage of [125I]albumin. When induction of haemorrhagic hypotension was combined with ganglionic blockade administration (Arfonad) and carotid artery occlusion (group ABC), significantly less blood had to be withdrawn than in groups BC (1.6 +/- 0.2 vs. 2.6 +/- 0.1 ml per 100 g body wt; P less than 0.05). The blood flows of the kidneys, small intestine, liver, spleen and skin were less compromised in group ABC. In addition, group BC had more profound metabolic acidosis and were more haemoconcentrated than group ABC; moreover, group BC, tended to be hypoglycaemic and showed intestinal mucosal damage, whereas neither of these effects occurred in group ABC.(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo phototoxicity of non-steroidal anti-inflammatory drugs evaluated by the mouse tail technique

Skin photosensitivity is a side-effect reported for several non-steroidal anti-inflammatory drugs (NSAID). In vitro studies have revealed phototoxic properties in a majority of these compounds with a preponderance for derivatives of propionic acid. Fourteen NSAIDs, the majority commercial preparations in clinical use, have been assayed by the mouse tail technique for in vivo phototoxicity evaluation. Intraperitoneal single doses in the range 12.5-200 mg/kg were given in combination with UVA irradiation for 5 h (total dose 54 J/cm2). The phototoxic reaction was measured 24 h later as the wet weight increase of tail tissue over non-irradiated, drug-treated controls. Four out of 9 propionic acid derivatives were phototoxic: tiaprofenic acid, carprofen, benoxaprofen and naproxen. Among NSAID compounds of other chemical structure only diclofenac and diflunisal were weakly photoactive. The propionic acid derivatives fenoprofen, flurbiprofen, ibuprofen, indoprofen and ketoprofen were negative, as were azapropazone, piroxicam and sulindac among the unrelated compounds. Phototoxicity is one important aspect of NSAID photosensitization. It is advisable to perform predictive studies including in vivo models, such as the mouse tail technique, before new NSAIDs are introduced on the market.