Aryl hydrocarbon receptor activity in human breast milk and cryptorchidism: A case-control study within the prospective Norwegian HUMIS cohort

BACKGROUND

The etiology of cryptorchidism remains poorly understood. Endocrine disrupting chemicals can impact estrogen signaling by interacting with aryl hydrocarbon receptor (AhR) activity.

OBJECTIVE

To evaluate whether AhR activity in breast milk samples is associated with cryptorchidism.

METHOD

We conducted a case-control study based on 199 mother-child pairs (n = 91 cases/108 controls) selected from the Norwegian Human Milk Study (2002-2009). We defined cases for cryptorchidism based on maternal reports at 1-, 6-, 12-, and 24- months after birth. Chemically- and biologically stable AhR activity (pg 2,3,7,8-TCDD equivalent (TEQ)/g lipid) was determined by DR- CALUX® assay in the mothers' milk collected at a median of 33 (10th-90th percentile: 18-57) days after delivery. We used multivariate logistic regression to compare AhR activity levels between cases and controls, and linear regression separately, to establish the relationship with the presence of 27 potential EDCs measured in breast milk and AhR activity.

RESULTS

The average estimated daily intake (EDI) of dioxin and (dioxin-like (dl)-compounds via breast milk is 33.7 ± 17.9 pg TEQ/kg bodyweight per day among Norwegian children. There were no significant differences in AhR activation in breast milk samples between cases with cryptorchidism and controls. Among the 27 chemicals measured in breast milk, AhR activity was (borderline) significantly associated with all dl-PCBs, three non-dioxin-like (ndl)-PCBs (PCB-74, PCB-180, PCB-194) and two organochlorine pesticides (OCPs; HCB, β-HCH). No associations between AhR activity and brominated flame retardants (PBDEs) or poly- and perfluoroalkyl substances (PFASs).

CONCLUSION

No association between AhR activity and cryptorchidism was found among Norwegian boys. The average EDI of dioxin and dl-compounds in exclusively breastfed Norwegian infants remains above the safety threshold and, therefore requires further reduction measures. Consistent with a possible role in the observed AhR activity, all dl-PCBs were associated with AhR activity whereas the association was null for either PBDEs or PFASs.

Magnetosphere-Ionosphere-Thermosphere Coupling Study at Jupiter Based on Juno's First 30 Orbits and Modeling Tools

The dynamics of the Jovian magnetosphere is controlled by the interplay of the planet's fast rotation, its solar-wind interaction and its main plasma source at the Io torus, mediated by coupling processes involving its magnetosphere, ionosphere, and thermosphere. At the ionospheric level, these processes can be characterized by a set of parameters including conductances, field-aligned currents, horizontal currents, electric fields, transport of charged particles along field lines including the fluxes of electrons precipitating into the upper atmosphere which trigger auroral emissions, and the particle and Joule heating power dissipation rates into the upper atmosphere. Determination of these key parameters makes it possible to estimate the net transfer of momentum and energy between Jovian upper atmosphere and equatorial magnetosphere. A method based on a combined use of Juno multi-instrument data and three modeling tools was developed by Wang et al. (2021, https://doi.org/10.1029/2021ja029469) and applied to an analysis of the first nine orbits to retrieve these parameters along Juno's magnetic footprint. We extend this method to the first 30 Juno science orbits and to both hemispheres. Our results reveal a large variability of these parameters from orbit to orbit and between the two hemispheres. They also show dominant trends. Southern current systems are consistent with the generation of a region of sub-corotating ionospheric plasma flows, while both super-corotating and sub-corotating plasma flows are found in the north. These results are discussed in light of the previous space and ground-based observations and currently available models of plasma convection and current systems, and their implications are assessed.

Anti-androgenic compounds in breast milk and cryptorchidism among Norwegian boys in the HUMIS birth cohort

The prevalence of cryptorchidism has increased over the past decades, yet its origins remain poorly understood. Testis descent is dependent on androgens and likely affected by endocrine disrupting compounds (EDCs), targeting the androgen receptor (AR). We investigated the association between anti-androgenic activity, not derived from natural hormones, in maternal breast milk and impaired testis descent among boys. We performed a case-control study based on 199 breast milk samples from 94 mothers of cryptorchid boys and 105 random non-cryptorchid boys participating in the Norwegian HUMIS (Human Milk Study) cohort. For each participant, apolar, and polar fractions were extracted, and combined to reconstitute a mixture. Anti-androgenic activity was measured in all three fractions using the human cell-based in vitro anti-AR CALUX® assay and expressed in μg of flutamide equivalent, a well-known antiandrogen. Results from fraction analyses were compared among boys with cryptorchidism and controls using multiple logistic regression, controlling for appropriate confounders identified using a directed acyclic graph. Children's daily exposure to anti-androgenic EDCs through breastfeeding was estimated to 78 μg flutamide eq./kg of body weigh/day. The activity was higher in the polar fraction (1.48 ± 1.37 μg flutamide eq./g of milk) mainly representing non-persistent chemicals, in contrast to other fractions. However, the activity in the polar extracts was decreased when in mixtures with the apolar fraction, indicating synergistic interactions. No significant difference in the activity was observed according to cryptorchid status for polar, apolar or mixed breast milk fractions. The study showed anti-androgenic activity in nearly all human milk samples, and at levels higher than the advisory threshold. However, no significant association was observed between cryptorchidism and antiandrogenic activity measured in either polar, apolar, or mixture fractions derived from breast milk.

A minimally fluoroscopic approach in AVNRT ablation reduces radiation exposure and number of RF applications without compromising safety, effectiveness and procedural time

Funding Acknowledgements

Type of funding sources: None.

Introduction

Radiofrequency ablation (RF) of atrioventricular nodal reentry tachycardia (AVNRT) using conventional fluoroscopy is associated with a significant radiation exposure to both patients and operators. 3D electro-anatomical mapping systems (EAMS) can reduce radiation exposure, but specific clinical studies on their use in AVNRT ablation still lack.

Purpose

The aim of this study was to determine if EAMS use in AVNRT ablation can reduce radiation exposure and to analyse its effects on clinical and procedural outcomes.

Methods

We selected 277 patients who underwent AVNRT RF ablation in a single center in Belgium between July 2015 and November 2019 and performed a retrospective analysis of 136 and 141 patients who respectively and consecutively underwent AVNRT ablation with a conventional fluoroscopic approach (Conventional group) and a minimally fluoroscopic approach using a 3D electro-anatomical mapping system to guide the procedure (Minimal fluoroscopy group). Conventional fluoroscopy was used in both groups to confirm AVNRT induction to avoid costs related to the use of EAMS catheters in case of non-induction.  We compared radiation dose, acute success/complication rates, procedural time and the number/time of RF applications in both groups.

Results

Radiation dose in the minimal fluoroscopy group was significantly lower compared to the conventional group (1179 vs. 2686 mgray.cm2, p < 0,0001) and fluoroscopic time was shorter (2,5 vs. 8,6 minutes, p < 0,0001). Procedural time (70 vs. 69 min, p = NS) and acute success rate (99% vs. 98%, p = NS) were not significantly different in the minimal fluoroscopy group compared to the conventional group, and no complications were observed in both groups. The number of RF applications was significantly lower when EAMS was used (6,2 ± 4,8 vs. 8,6 ± 7,6 RF application, p = 0,01) while the RF application time was not significantly different (56,8 ± 51,2 1 vs. 65,3 ± 86 seconds, p = NS).

Conclusion

AVNRT catheter ablation using a minimally fluoroscopic approach with 3D electro-anatomical mapping systems reduces radiation exposure without compromising safety, effectiveness and procedural time. EAMS use is associated with a reduction in the number of RF applications suggesting a higher precision and stability of ablation catheters during RF application.

Antagonistic activity towards the androgen receptor independent from natural sex hormones in human milk samples from the Norwegian HUMIS cohort

In this paper, we investigated the possible presence of endocrine disrupting chemicals (EDCs) based on measuring the total estrogenic and androgenic activity in human milk samples. We used specific bioassays for analysis of the endocrine activity of estrogens and estrogen-like EDCs and androgens and androgen-like EDCs and developed a separation method to evaluate the contribution from natural hormones in comparison to that of EDCs to total endocrine activities. We extracted ten random samples originating from the Norwegian HUMIS biobank of human milk and analyzed their agonistic or antagonistic activity using the ERα- and AR CALUX® bioassays. The study showed antagonistic activity towards the androgen receptor in 8 out of 10 of the assessed human milk samples, while 2 out of 10 samples showed agonistic activity for the ERα. Further investigations demonstrated anti-androgenic activity in the polar fraction of 9 out of 10 samples while no apolar extracts scored positive. The culprit chemicals causing the measured antagonistic activity in AR CALUX was investigated through liquid chromatography fractionation coupled to bioanalysis and non-target screening involving UHPLC-Q-TOF-MS/MS, using a pooled polar extract. The analysis revealed that the measured anti-androgenic biological activity could not be explained by the presence of endogenous hormones nor their metabolites. We have demonstrated that human milk of Norwegian mothers contained anti-androgenic activity which is most likely associated with the presence of anthropogenic polar EDCs without direct interferences from natural sex hormones. These findings warrant a larger scale investigation into endocrine biological activity in human milk, as well as exploring the chemical sources of the activity and their potential effects on health of the developing infant.

Purification of a Tumoral Marker Recognized by Monoclonal Antibody Po66 and Associated with Human Lung Squamous Cell Carcinoma

Monoclonal antibody (MAb) Po66, a murine IgG1, was raised by immunization against human lung squamous cell carcinoma. When injected intravenously, Po66 showed prolonged retention in the tumor. It recognized an intracellular antigen. The human lung squamous carcinoma cell line SK-MES-1 expresses the antigen recognized by MAb Po66 and was used as a source of biological material for its purification. The SK-MES-1 cell line was labeled in culture with [35S]methionine and its lysate was immunoprecipitated with Po66 immobilized on Protein G-Sepharose. The precipitate contained three proteins (47, 50 and 69 kDa) absent in the controls. The 69 kDa polypeptide was further purified by anion exchange and immunoaffinity chromatographies. To date, no other tumor marker expressed in non-small cell lung cancer with these characteristics has been described and as such this marker is interesting for future use in immunotherapy and in diagnosis.

Effect of repeated exposure to AQUI-S® on the viability and growth of Neoparamoeba perurans

There have been recent efforts amongst immunologists to develop approaches for following individual fish during challenges with viral and bacterial pathogens. This study contributes to assessing the feasibility of using such approaches to study amoebic gill disease (AGD). Neoparamoeba perurans, agent of AGD, has been responsible for widespread economic and fish loss in salmonid aquaculture. With the emergence of AGD in Europe, research into infection dynamics and host response has increased. This study investigated the effect of repeat exposure to anaesthesia, a necessary requirement when following disease progression in individual fish, on N. perurans. In vitro cultures of N. perurans were exposed every 4 days over a 28-day period to AQUI-S^® (isoeugenol), a popular anaesthetic choice for AGD challenges, at a concentration and duration required to sedate post-smolt salmonids. Population growth was measured by sequential counts of amoeba over the period, while viability of non-attached amoeba in the culture was assessed with a vital stain. AQUI-S^® was found to be a suitable choice for in vivo ectoparasitic challenges with N. perurans during which repetitive anaesthesia is required for analysis of disease progression.

Development, Characterisation and Application of Monoclonal Antibodies for the Detection and Quantification of Infectious Salmon Anaemia Virus in Plasma Samples Using Luminex Bead Array Technology

Infectious salmon anaemia virus (ISAV) is an orthomyxovirus that has had a significant economic impact on Atlantic salmon farming in Europe, North America and Chile. Monoclonal antibodies (mAbs) were developed against Segment 3 (encoding the viral nucleoprotein, NP) of the virus. Six of the mAbs were shown to be specific to ISAV and recognised all isolates from Scotland, Norway and Canada. They reacted with ISAV in enzyme-linked immunosorbent assay (ELISA), indirect fluorescent antibody technique (IFAT) and western blotting. They were also used to develop a novel detection method based on Luminex (Bio-Plex) bead-based flow cytometric technology for the detection of ISAV in the plasma of Atlantic salmon (Salmo salar L.) smolts experimentally infected with ISAV. Fish were challenged by intraperitoneal (i.p.) injection of virus at 50% Tissue Culture Infective Dose (TCID50) = 2.8 x106 per animal. Virus present in plasma of infected fish, collected at 0, 4, 8, 12, 16, 21 and 28 days post infection using a non-lethal sampling method (n = 12 at each time point), was quantified using the optimised Bio-Plex assay. The results obtained with this assay were compared with absolute quantification of the virus by RT-qPCR using SYBR Green I and TaqMan chemistries. The Bio-Plex assay developed using the NP mAbs appears to be a rapid, sensitive method for detecting and quantifying ISAV in small volumes of fish plasma and has the potential to be multiplexed for the detection of other fish pathogens (e.g. during co-infections). To our knowledge this is the first report of the use of Luminex (Bio-Plex) technology for the detection of a fish pathogen.

Identification and characterisation of TLR18-21 genes in Atlantic salmon (Salmo salar)

Teleost fish possess many types of toll-like receptor (TLR) some of which exist in other vertebrate groups and some that do not (ie so-called "fish-specific" TLRs). In this study, we identified in Atlantic salmon (Salmo salar) whole-genome shotgun (WGS) contigs seven TLRs that are not found in mammals, including six types of fish-specific TLRs (one TLR18, one TLR19, and four TLR20 members (two of which are putative soluble forms (s)) and one TLR21. Phylogenetic analysis revealed that teleost TLR19-21 are closely related with murine TLR11-TLR13, whilst teleost TLR18 groups with mammalian TLR1, 2, 6 and 10. A typical TLR protein domain structure was found in all these TLRs with the exception of TLR20b(s) and TLR20c(s). TLR-GFP expression plasmids transfected into SHK-1 cells showed that salmon TLR19, TLR20a and TLR20d were preferentially localised to the intracellular compartment. Real time PCR analysis suggested that salmon TLR19-TLR21 are mainly expressed in immune related organs, such as spleen, head kidney and gills, while TLR18 transcripts are more abundant in muscle. In vitro stimulation of primary head kidney cells with type I IFN, IFNγ and IL-1β had no impact on TLR expression. Infectious salmon anaemia virus (ISAV) infection, in vivo, down-regulated TLR20a, TLR20b(s), TLR20d and TLR21 in infected salmon kidney tissue. In contrast, up-regulation of TLR19 and TLR20a expression was found in posterior kidney in rainbow trout with clinical proliferative kidney disease (PKD).

Serum anti-p53 antibodies in patients with squamous cell carcinoma of the esophagus

Immunoassay of serum anti-p53 antibodies was performed in a series of 63 patients with squamous cell carcinoma of the esophagus. p53 alterations were also analyzed with DGGE to detect gene mutations (n=53) and by immunohistochemistry to assess overexpression of p53 (n=43). An immune response was observed in 16 sera (25%). The corresponding biopsies all had a p53 gene mutation or overexpression of protein p53. We were unable to demonstrate any significant relationship between habitual tumor parameters (localization, cell differentiation, TNM stage) and development of p53 alterations. However, none of the patients with a localized tumor developed an immune response, while some of them had a muted gene or overexpressed p53.

Interferon response following infection with genetically similar isolates of viral haemorrhagic septicaemia virus (VHSV) exhibiting contrasting virulence in rainbow trout

Isolates of viral haemorrhagic septicaemia virus (VHSV) were identified which are genetically similar yet, based on their isolation history were considered likely to differ in virulence in juvenile rainbow trout. An experimental infection study was performed in order to verify this hypothesis and provide an experimental infectivity model with which to investigate the basis for susceptibility of rainbow trout to this commercially important virus. Significant differences in mortality were obtained following both intraperitoneal (IP) injection and immersion challenges with an early marine (DK-M.Rhabdo) and early rainbow trout VHSV isolate (DK-F1) respectively. Expression of Type I IFN, Mx1 (an IFN-inducible protein), and viral genes (encoding nucleo-, phospho-, matrix, glyco- and non-viron proteins) was studied in sequential tissue samples using real-time quantitative PCR (QPCR). Resulting data revealed a significant increase in IFN and Mx1 expression detected in fish challenged by IP injection with both isolates. Expression levels of these genes were directly related to the degree of viral replication as measured by the expression of VHSV RNAs. In immersion-challenged fish a significant increase in Mx1 was observed only when using the virulent isolate DK-F1; however no elevated host response was detectable in fish challenged with the marine isolate DK-M.Rhabdo. Quintessentially the inability to detect any virus in trout challenged with the marine isolate via immersion suggests the virus was incapable of establishing infection. The mechanisms for this appear to be more related to initial cellular entry and replication rather than due to the overcoming of initial infection via an elevated host innate immune response.

Histology, immunocytochemistry and qRT-PCR analysis of Atlantic salmon, Salmo salar L., post-smolts following infection with infectious pancreatic necrosis virus (IPNV)

Infectious pancreatic necrosis (IPN) is a very serious viral disease in terms of its impact on production of Atlantic salmon, Salmo salar L., fry and post-smolts. Post-smolts of Atlantic salmon were injected with infectious pancreatic necrosis virus (IPNV) and cohabited with naive fish to produce natural infection. Cohabitant fish were sampled every 2 days, up to day 36 post-infection (p.i.). From 90 cohabitant fish, 11 (12.2%) were positive by immunohistochemistry (IHC). The first detection of IPNV by IHC occurred on day 16 p.i. which coincided with the onset of mortality in this group. Besides the pancreas, the liver was found to be a key target organ for IPNV. For the first time, the virus was observed in the islets of Langerhans and in the kidney corpuscles of Stannius which suggests that the virus could affect the fish's metabolism. The liver of two fish, which showed the most widespread presence of IPNV by IHC, had a pathology including focal necrosis and widespread presence of apoptotic hepatocytes, many of which did not stain for virus by IHC. Up-regulation of cytokine gene expression was found only in the IHC-positive (IHC+ve) fish and reflected the level of infection as determined by IHC positivity of the liver. In most fish, interferon (IFN), Mx, γIFN and γIP were up-regulated in liver and kidney, while only IFN and Mx were up-regulated in gill. IL1β and TNFα were not induced in any tissue. The gill showed variable levels of constitutive expression of IL1β and γIFN. The two fish with liver pathology had the highest level of IFN expression, especially relative to the level of Mx expression, in the liver compared with the other IHC+ve fish which did not have a liver pathology. The results suggest that following widespread infection of hepatocytes, the cells may over-produce IFN, resulting in apoptosis of neighbouring cells with subsequent death from liver failure.

Identifying potential virulence determinants in viral haemorrhagic septicaemia virus (VHSV) for rainbow trout

We identified viral haemorrhagic septicaemia virus (VHSV) isolates classified within Genotype Ib which are genetically similar (>99.4% glycoprotein amino acid identity) yet, based on their isolation history, were suspected to differ in virulence in juvenile rainbow trout. The virulence of an isolate recovered in 2000 from a viral haemorrhagic septicaemia disease episode in a marine rainbow trout farm in Sweden (SE-SVA-1033) was evaluated in juvenile rainbow trout via intraperitoneal injection and immersion challenge alongside 3 isolates recovered from wild-caught marine fish (DK-4p37, DK-5e59 and UKMLA98/6HE1) suspected of being of low pathogenicity to trout. Mortality data revealed that isolate SE-SVA-1033 caused VHSV-specific mortality in both intraperitoneal and immersion challenges (75.0 and 15.4%, respectively). The remaining Genotype Ib isolates caused significantly lower mortalities using the same experimental infection routes (<35.0 and <2.0%, respectively). Having identified VHSV isolates with clear differences in their pathogenicity, coding and inter-genic non-coding regions of 2 isolates (SE-SVA-1033 and DK-4p37) were determined and compared in order to identify potential markers responsible for the observed differences in virulence. Only 4 predicted amino acid substitutions were identified across the genome sequenced; these occurred in the N (R46G), G (S113G), NV (L12F) and L (S56A) proteins. These findings form the basis for further studies aimed at determining the biological significance of these mutations and suggest that small changes at the molecular level can cause significant changes in the virulence properties of VHSV isolates.

The effect of sub-culturing on the basal level of type I interferon (IFN) gene expression in the Salmon Head Kidney (SHK-1) cell line

Over sub-culturing a cell line generates a selective pressure which can result in key cellular functions being altered such as gene and protein expression. The present study set out to determine whether serial sub-culturing affects the antiviral state of the Salmon Head Kidney (SHK-1) cell line. Cells were cultured under constant conditions and real-time PCR was performed to measure the level of interferon (IFN) and Mx gene expression over different passage numbers. A significant increase in the basal level of IFN and Mx gene expression was recorded at passage number 58 (3 and 14-fold increase versus passage number 53), suggesting a sub-culturing effect on the type I IFN response in SHK-1 cells. Passage dependent variations in morphology and cell sub-populations have been previously observed in SHK-1 cells. Such variations in cell sub-types were suspected to be responsible for the fluctuations in IFN and Mx gene expression recorded in this study.

A sensitive loop-mediated isothermal amplification (LAMP) method for detection of Renibacterium salmoninarum, causative agent of bacterial kidney disease in salmonids

Loop-mediated isothermal amplification (LAMP) is a novel technique for nucleic acid amplification with high specificity, sensitivity and rapidity and does not require expensive equipment or reagents. In the present study, we developed and evaluated a LAMP method for the rapid detection of Renibacterium salmoninarum causing the bacterial kidney disease in salmonids. This method was more sensitive than quantitative real-time polymerase chain reaction (qPCR). Using DNA template extracted from cultured R. salmoninarum, the LAMP method gave an amplification signal from template diluted to 10(-8) while the limit of detection of qPCR was10(-7). The LAMP method was also highly specific and did not amplify DNA purified from five other Gram-positive and -negative bacterial fish pathogens. The method also worked well using extracts of macrophages infected with R. salmoninarum and kidney material from rainbow trout, which were positive for R. salmoninarum by qPCR and crude R. salmoninarum culture. There was some evidence for inhibitors of the LAMP reaction in the kidney samples, which was overcome by diluting the sample.

Molecular characterization of IRF3 and IRF7 in rainbow trout, Oncorhynchus mykiss: functional analysis and transcriptional modulation

Interferon regulatory factors (IRF) 3 and 7 in mammals are known to be crucial in regulating the type I interferon (IFN) response to viral infection as part of transcriptional complexes binding to IRF-binding elements (IRF-Es) and interferon stimulatory response elements (ISREs) within IFN and interferon-stimulated genes (ISGs). Here we report the sequencing and characterization of full-length cDNA homologues of rainbow trout (rt)IRF7 and, for the first time in fish, IRF3. RtIRF3 consists of 2127 bp with a 159 bp 5'-UTR-containing two upstream AUGs and a 573 bp 3'-UTR. RtIRF7 was found to be 2055 bp, with a 102 bp 5'-UTR and a 705 bp 3'-UTR. The open reading frames (ORFs) translate into 464 amino acid and 415 amino acid proteins, respectively, each possessing a putative DNA-binding domain (DBD) containing a tryptophan cluster, which is characteristic of all IRF family members. The presence of putative IRF association domain (IAD)s, serine-rich C terminal domains (poorly conserved in trout IRF3), and phylogenetic analysis places the two genes in the IRF3 subfamily. Both genes were found to be upregulated by poly I:C, type I recombinant rainbow trout (r) IFN (second isoform, type I rIFN), type II rIFN (rIFNgamma), LPS, and rIL-1beta in the trout macrophage cell line, RTS-11. Poly I:C and type I rIFN also induced IRF3 and IRF7 expression in a trout fibroblast cell line (RTG-2). Transient transfection of RTG-2 cells with each IRF fused to GFP revealed a predominant cytoplasmic distribution found most intensely around the nucleus and, to a lesser extent, within cell nuclei. Transient transfection of rtIRF3 in the Mx-1-luciferase reporter cell line, RTG-P1, revealed a modest increase in luciferase activity relative to the vehicle control, which was lost in cells over-expressing a DBD-truncated form of rtIRF3. Both full-length and DBD-truncated forms of rtIRF7 increased reporter activity relative to the control, although to a non-significant extent. Electromobility shift assays (EMSAs) did not reveal a specific interaction between each IRF and the ISRE element found in the Mx-1 promoter, although the Mx-1 ISRE bound specifically to endogenous transcriptional complexes. These data support the premise that rtIRF3 and rtIRF7 are important molecules in the regulation of antiviral responses in fish, with the impact of rIFNgamma on rtIRF3/7 expression implying a role for these IRFs in immune processes other than type I IFN-driven antiviral responses.

Induction of Mx protein in Atlantic cod with poly I:C: immuno-cross reactive studies of antibodies to Atlantic salmon Mx with Atlantic cod

A polyclonal rabbit antiserum directed against the conserved region of the Atlantic salmon antiviral Mx1 protein was used to detect the putative Atlantic cod Mx protein using Western and dot blotting. A doublet band at about 75 kDa and 65 kDa was detected by Western blotting in kidney and spleen extracts of cod 3 and 4 days after i.p. injection with poly I:C but not in control fish injected with PBS. In blood leucocyte lysates, similar immunostaining could also be detected in Atlantic cod weakly after injection with PBS and more intensely after injection with poly I:C, suggesting some constitutive expression of Mx protein by leucocytes. Dot blot analysis showed that the Mx protein level was significantly higher in spleen, kidney, liver and gill of cod at least up to 4 days after injection with poly I:C when compared with the PBS-injected controls.

Expression of Mx protein in tissues of Atlantic salmon post-smolts--an immunohistochemical study

A rabbit antiserum was produced from a 12-amino acid long peptide common to the 3 known isoforms of Atlantic salmon Mx proteins. The antibody stained ASK-1 cells 48h after stimulation with poly I:C. In Western blots of these cells, the antibody stained a doublet with MW about 75kDa and another band at about 65kDa, typical of the MW of Atlantic salmon Mx. Western blots of kidney from IPNV-injected salmon showed a similar staining pattern. In immunohistochemistry, the antibody stained the gill, kidney and liver tissue of a fish infected with IPNV by cohabitation. These tissues also expressed high levels of interferon (IFN) and Mx transcripts as determined by real-time qRT-PCR. Normal healthy salmon post-smolts sampled at 4-8 weeks after transfer to sea water had very low-level expression of IFN and Mx transcripts. However, at 4 and 5 weeks after sea water transfer the gill, kidney and liver of these fish stained strongly for Mx protein. Thereafter, immunostaining of Mx markedly diminished in all tissues, persisting weakly in the gill. It has been reported that Atlantic salmon smolts constitutively express IFN and Mx transcripts around the time of smolting. Presumably the Mx protein detected in the tissues for about 6 weeks after transfer to sea water resulted from such a transcriptional event. As Mx is known to provide protection against IPNV infections it is tempting to associate the duration of persistence of Mx protein with the outbreaks of IPN-related mortalities in post-smolts, 6-8 weeks after transfer to sea water.

Expression kinetics of ISG15 and viral major capsid protein (VP2) in Atlantic cod (Gadus morhua L.) fry following infection with infectious pancreatic necrosis virus (IPNV)

Atlantic cod fry (1g) were infected by intraperitoneal injection with IPNV and samples of liver were taken every second day from four fish up to day 21. Samples were analysed for levels of viral transcripts by real time RT-PCR and the induction of expression of interferon stimulated gene 15 (ISG15) transcripts were estimated by conventional RT-PCR relative to beta-actin. Mortality of over 40% occurred in infected groups between day 6 and 12 after infection. Levels of viral transcripts were low on day 1, rose on day 3, peaked on day 5 remaining high till day 13, and thereafter declined to low levels by day 21. The highest levels of viral transcripts, therefore, coincided with the onset and duration of mortality, but low levels persisted in surviving fish. ISG15 transcripts in control fish were detectable at low levels. Following infection with IPNV there was a marked increase in transcripts on day 3 and this level persisted up to day 21. This is the first report that IPNV induces the expression of the ISG15 gene in Atlantic cod.

Expression of interferon type I and II, Mx and gammaIP genes in the kidney of Atlantic salmon, Salmo salar, is induced during smolting

The expression in kidney tissue of interferon type I (IFNalpha) and type II (IFNgamma) genes and two of their inducible genes, Mx and gammaIP were monitored, using qRT-PCR, in a population of Atlantic salmon prior to and over the period of smolting and sea water transfer. The smolting process was induced by photoperiod manipulation in October and smolts were transferred to sea water in December. Prior to extending the light period in October, the fish showed extremely low level expression of the genes assayed. However, immediately on extending the light and up until 1 week after transfer to sea water, 26 of the 90 fish sampled showed up-regulated expression for IFNalpha, Mx and gammaIP. The highest levels were shown by two fish on the 2 days prior to sea water transfer. Eleven fish displayed elevated expression of IFNgamma but there was no apparent association with smolting or sea water transfer or expression of the other genes. At the end of the sampling period, 30 fish were tested by standard virological methods and found to be virus free. The results indicate that during the smolting process, Atlantic salmon consititutively express IFNalpha and Mx mRNA. Those individuals which express Mx close to the time of transfer to sea water would be expected to have high levels of the anti-viral Mx protein in tissues for the longest time after sea water transfer. This could provide an innate defence against viral pathogens which post-smolts may encounter for the first time on entering the marine environment. Those individuals which express Mx early in the smolting process may be more at risk of developing IPN or other viral diseases as post-smolts.

Expression kinetics of interferon and interferon-induced genes in Atlantic salmon (Salmo salar) following infection with infectious pancreatic necrosis virus and infectious salmon anaemia virus

Infectious pancreatic necrosis virus (IPNV) and infectious salmon anaemia virus (ISAV) are economically important pathogens of the salmonid aquaculture industry. Atlantic salmon were challenged by intraperitoneal injection (i.p.) with either virus followed by time-course sampling. Cohabiting fish in the IPNV challenge were also sampled. Kidney tissue was analysed using a TaqMan real-time PCR assay to measure the expression of a range of host immune genes in relation to the endogenous control, elongation factor 1 alpha (ELF). Host genes measured included Mx, type I and type II interferon (IFN), gammaIFN induced protein (gammaIP), interleukin-1 beta (IL-1beta) and tumour necrosis factor alpha (TNF-alpha). Viral levels were also measured. In i.p. injected fish, both viruses greatly induced expression of Mx, gammaIP, type I and type II IFN by day 6 post-infection, however only ISAV caused substantial mortality. Some differences between the expression kinetics produced by both viruses were noted. Infection with ISAV increased IL-1beta expression following day 6, but no effect was seen in fish infected with IPNV. Neither virus induced TNF-alpha expression. This study confirms the presence of both type I and type II IFN responses and their induced genes in Atlantic salmon upon infection with an orthomyxovirus and a birnavirus.

Expression of Mx mRNA following infection with IPNV is greater in IPN-susceptible Atlantic salmon post-smolts than in IPN-resistant Atlantic salmon parr

The Mx response was compared in parr and post-smolt Atlantic salmon following intra-peritoneal injection of the same dose of Infectious Pancreatic Necrosis Virus (IPNV) per g of fish. Mx gene expression, measured by quantitative RT-PCR in liver, showed a maximum level 3days after injection in parr with undetectable levels on day 7. In post-smolts, similar levels as in parr were attained on day 3, but levels then continued to rise on day 5 and 7 to about 10 times higher than the peak level in parr. Poly I:C injected parr showed Mx levels similar to IPNV injected post-smolts. Mortality from IPN in post-smolts occurred on days 6 and 7. Levels of IPN VP2 transcripts in parr were very low and did not increase with time, suggesting viral replication was low. Individual variation in levels of Mx and IPN VP2 gene transcripts was very high in post-smolts and although data is limited there was an inverse relationship between the levels of Mx and VP2, suggesting that individuals with high Mx levels on day 5 may be able to prevent viral replication. This contrasts with the response in parr, where IPN-resistance was not associated with a high Mx response.

Expression of the glycoprotein of viral haemorrhagic septicaemia virus (VHSV) on the surface of the fish cell line RTG-P1 induces type 1 interferon expression in neighbouring cells

In the present study using a luciferase/Mx promoter reporter system, it was shown that the rainbow trout gonad cell line (RTG-P1), a fibroblastic cell line, produces IFN when transfected with a plasmid encoding the glycoprotein of VHSV but not with plasmid vector alone. Only a small percentage of the cells expressed the G protein on the surface membrane as indicated by immunostaining of transfected cells. When transfection was performed in the presence of monoclonal antibodies (Mab) to the glycoprotein, the production of interferon mRNA transcripts was reduced by over 50%. This indicates that the surface expression of G protein was the major mechanism of interferon induction and that most of the interferon was being expressed by cells neighbouring the transfected cells.

An assessment of immunostimulants as Mx inducers in Atlantic salmon (Salmo salar L.) parr and the effect of temperature on the kinetics of Mx responses

The aims of this study were (i) to identify alternative Mx stimulatory compounds in Atlantic salmon (Salmo salar L.) and to characterise the kinetics and intensity of the stimulated responses and (ii) to investigate the effect of temperature on such responses by semi-quantitative RT-PCR. Mx transcripts were measured in Atlantic salmon parr kept at 14 degrees C and injected with either LPS, the synthetic double-stranded polyribonucleotide poly I:C, Vibrio anguillarum serotypes I and II-ordalii bacterin, beta-glucan, whole yeast cells or yeast RNA. Sampling periods lasted until transcripts were undetectable or up to three weeks after immunisation. The effect of temperature on poly I:C-induced Mx response was studied by injecting parr kept at 6 degrees C. Newly hatched salmon fry were immersed once, twice or three times in the Vibrio bacterin diluted five or 10 times and sampled for three weeks. None of the yeast compounds induced Mx expression in Atlantic salmon parr. LPS induced a very low Mx response 2 and 3 days after injection. The Vibrio bacterin administered by injection in parr (but not by immersion in fry) resulted in strong Mx induction on days 2 and 3, disappearing by day 6. Poly I: C-induced Mx responses that were more intense and longer lasting than those induced by the bacterin, peaking on day 3 and lasting over 6 days, disappearing by day 9 at 14 degrees C. Lower temperature caused a longer lasting Mx response to poly I:C (at least 21 days), which peaked on days 7-14, with a similar intensity and no delayed onset as compared with the response at 14 degrees C. However, some toxicity of the poly I:C was indicated in treatments at 6 degrees C.

Recursive surface impedance matrix methods for ultrasonic wave propagation in piezoelectric multilayers

Two recursive surface impedance methods are described for acoustic wave propagation in multilayered piezoelectric structures. Both methods have the advantage of conceptual simplicity and flexibility brought about by the transfer matrix method. Moreover they do not have a priori computational limitations with respect to the total number of layers of the stratified structure nor with respect to the thickness of individual layers; nor is the computational stability limited by the frequency range. For both methods, numerical simulations were carried out in order to illustrate their performances and robustness when combined with suitable recursive numerical algorithms.

DNA vaccination against viral haemorrhagic septicaemia (VHS) in rainbow trout: size, dose, route of injection and duration of protection-early protection correlates with Mx expression

Rainbow trout of different sizes (10 and 100g) were injected intramuscularly (i.m.) or intraperitoneally (i.p.) with different doses (range 10 ng-10 microg) of a viral haemorrhagic septicaemia (VHS)-DNA vaccine (pcDNA3vhsG). As controls, fish were injected with the pcDNA3 plasmid alone, or with inactivated VHS virus. Fish were challenged at different times post-vaccination (p.v.) to assess protection. At certain times p.v., serum samples were analysed for neutralising antibody and liver tissue was analysed for Mx mRNA expression. A DNA dose of 0.5 microg injected by the i.m. route induced protection in fish of all sizes in challenges performed either 1 or 4 weeks p.v. This dose also conferred effective protection up to 9 months p.v. in fish >100 g. With lower doses of DNA (0.1 and 0.01 microg) and challenge at 4 weeks p.v., 10 g fish were partially protected but protection was not observed in 100 g fish. Vaccination by the i.p. route induced no or lower levels of protection compared with the i.m. route. Fish vaccinated with 0.5 microg DNA i.m. had no detectable serum neutralising antibody (NAb) at 4 weeks p.v. (with the exception of a single 10 g fish) but antibody was detected at 8 weeks and 6 months p.v. but not at 9 months p.v. However, cohorts of these fish showed effective protection at all timepoints. Lack of detectable levels of NAb (at 9 weeks p.v.) despite partial protection in challenge at 4 weeks p.v. was also observed with 0.01 microg doses of DNA i.m. NAb was detected in sera of fish at 8 weeks after vaccination with 0.1 microg i.m. but not in fish vaccinated with doses of 0.01-0.5 microg i.p. Early protection (1 week p.v.) correlated with elevated Mx gene expression.

Is a cooled tip catheter the solution for the ablation of the cavotricuspid isthmus?

To test the theoretical superiority of irrigated tip catheters to achieve complete cavotricuspid isthmus block, a 4-mm cooled tip catheter was compared to a conventional 8-mm tip catheter with a double temperature sensor in the cavotricuspid isthmus (CTI) ablation. The study prospectively enrolled 60 patients (47 men, mean 65 +/- 10 years) with common flutter divided in group 1 (n = 30) assigned to an 8-mm tip catheter versus group 2 (n = 30), assigned to an internal circuit, irrigated tip catheter. Linear radiofrequency applications were performed in a point-by-point protocol to achieve complete CTI block. Complete CTI block was achieved in 29 patients in each group. Mean durations of procedure and fluoroscopy were 91 versus 90 and 40 versus 33 minutes in group 1 versus 2, respectively, (NS). The mean number/patient of RF pulses to interrupt atrial flutter was four in group 1 and eight in group 2 (P = 0.034), and 11 and 13, respectively, to interrupt CTI conduction (NS). The total energy delivered was similar in both groups (29,237 vs 23,236 W/s, NS). CTI ablation with a conventional 8-mm tip catheter versus an irrigated tip catheter was associated with similar success rates, procedure duration, and fluoroscopic exposure. The technical complexity of the cooled tip catheter renders it less competitive.

[The new German law on foreigners' residency: change and continuity]

"This article about the new German law on foreigners which came [into] force on 1-1-91, emphasizes the changes made to the 1965 law and the differences between the situations of foreigners in France and Germany. Two changes of attitude are to be noted: the introduction of a right of residence and of an 'earlier' naturalisation. This naturalisation which is limited to young foreigners and foreigners who have been living in Germany for a long time, finally gets away from the principles of racial...tendencies [i.e.] the belonging to the socio-cultural German Community." (SUMMARY IN ENG AND GER)

Differentiation of the P-gp and MRP1 multidrug resistance systems by mobile lipid 1H-NMR spectroscopy and phosphatidylserine externalization

We have previously demonstrated that proton NMR spectra of fatty acid chains in erythroleukemia K562 wild-type cells and their MDR1 counterparts show variations related to the phenotype over-expressing the P-glycoprotein (P-gp). Human lung cancer cells whose multidrug resistance (MDR) counterparts over-express the multidrug resistance-associated protein MRP1 have not yet been studied by NMR. Both P-gp and MRP1 belong to the same ATP-binding cassette transporter superfamily. A comparison of NMR spectra from both these multidrug-resistance phenotypes showed that the results previously obtained on the MDR1 family are not valid for MRP1. Furthermore, flow cytofluorimetry studies with external phosphatidylserine labelling showed that P-gp and MRP1 overexpressions have strong but differentiated effects on cell lipid pools.

Red and white muscle development in the trout (Oncorhynchus mykiss) as shown by in situ hybridisation of fast and slow myosin heavy chain transcripts

The axial muscle of most teleost species consists of a deep bulk of fast-contracting white fibres and a superficial strip of slow-contracting red fibres. To investigate the embryological development of fast and slow muscle in trout embryos, we carried out single and double in situ hybridisation with fast and slow myosin heavy chain (MyHC)-isoform-specific riboprobes. This showed that the slow-MyHC-positive cells originate in a region of the somite close to the notochord. As the somite matures in a rostrocaudal progression, the slow-MyHC-positive cells appear to migrate radially away from the notochord to the lateral surface of the myotome, where they form the superficial strip of slow muscle. Surprisingly, the expression pattern of the fast MyHC showed that the differentiation of fast muscle commences in the medial domain of the somite before the differentiation and migration of the slow muscle precursors. Later, as the differentiation of fast muscle progressively spreads from the inside to the outside of the myotome, slow-MyHC-expressing cells become visible medially. Our observations that the initial differentiation of fast muscle takes place in proximity to axial structures and occurs before the differentiation and migration of slow muscle progenitors are not in accord with the pattern of muscle formation in teleosts previously described in the zebrafish Danio rerio, which is often used as the model organism in fishes.

The rainbow trout (Oncorhynchus mykiss) Mx1 promoter. Structural and functional characterization

Mx1 gene expression was studied in the rainbow trout (Oncorhynchus mykiss) gonad (RTG) (fibroblast) cell line. RT-PCR analyses showed that both poly I:C and interferon containing supernatants induced expression of Mx1 in RTG cells. Kinetic analyses suggest that poly I:C acts indirectly through the production of interferons (IFN), as shown in other studies. By gene walking with trout genomic DNA the regulatory sequence of the Mx1 gene was cloned and sequenced. Sequence analysis showed that the 5' flanking region has a structure, which is typical for an interferon-induced gene promoter. Relative to the transcription start, it has a TATA box at -29 to -25, a 13 nucleotide interferon response element (ISRE) between -101 to -89, and a Sp1 binding site at -382 to -374. This region, with a single ISRE, is enough to induce strong expression of a luciferase reporter gene after stimulation of RTG cells with poly I:C. A time-course of induction of this reporter construct showed maximal expression (22-fold increase) after incubation with 100 microg mL(-1) poly I:C for 48 h. An optimized method of transient transfection of RTG cells is also described.

Expression of MAGE genes in esophageal squamous-cell carcinoma

The genes MAGE-1, -2, -3 and -4 are expressed in tumors of different histological types, but not in normal tissues, with the exception of testis and placenta. Short peptides derived from MAGE-1 and MAGE-3 gene products are recognized by cytolytic T lymphocytes when presented by HLA-class-I molecules, and represent potential targets for specific immunotherapy. We have determined whether esophageal carcinoma patients should be eligible for MAGE-peptide-based vaccine therapies. The expression of genes MAGE-1, -2, -3 and -4 in tumor samples was assessed by reverse-transcription and polymerase-chain-reaction amplification. Out of the 49 esophageal squa-mous-cell carcinomas studied, 53% expressed MAGE-1, 49% MAGE-2, 47% MAGE-3 and 71% MAGE-4. Eighty-four percent of the tumors expressed one or more of the four MAGE genes. Owing to the high incidence of MAGE gene expression in esophageal squamous-cell carcinoma, a large proportion of patients could be suitable candidates for immune therapies involving tumor-specific antigens encoded by MAGE genes.

Fate of mouse macrophages radiolabelled with PKH-95 and injected intravenously

Mouse macrophages purified by elutriation from thioglycollate-induced peritoneal exudate cells were labelled with indium-111-oxine and injected intravenously into mice. A substantial amount of unbound radioactivity remained in the circulation, suggesting that the radionuclide was not stably bound to the cells. Culture experiments with radiolabelled cells showed that indium-111 was released in the medium. Another cell marker, PKH-95, an iodine-125-labelled aliphatic compound insertable into the cell membrane, bound more stably than indium-111. Five minutes after injection of 125I-PKH-95-labelled macrophages, about 98% of the cells were in a non-circulating pool. It was checked that PKH-95 labelling did not compromise the viability and functions of the macrophages and that autologous erythrocytes and blood mononuclear cells labelled with PKH-95 remained in the circulation after i.v. injection. One hour after injection, 125I-PKH-95-labelled macrophages were distributed mainly in lung (36%), liver (19%) and spleen (5%). Subsequently, radioactivity decreased in the lung while increasing in liver, spleen and in an artificially induced footpad inflammation. The radioactivity accumulation in the inflammation persisted at least for 7 days. It represented a small proportion of radioactivity injected (0.2%) but was trapped very specifically in the inflammation. This raised the hypothesis that macrophages of the non-circulating pool could be released in the circulation and recruited into the inflammation with slow kinetics.

Puerperal presentation of a living abdominal pregnancy

BACKGROUND

Abdominal and heterotopic pregnancies appear to be increasing in incidence.

CASE

We report a case of puerperal presentation of a living heterotopic pregnancy in an African woman. The patient presented 6 days postpartum with fever and abdominal pain. The correct diagnosis of heterotopic pregnancy was not considered, and for 9 days she was treated for presumed puerperal sepsis. It was only upon abdominal x-ray that the diagnosis was made. The patient underwent laparotomy with delivery of a living male neonate weighing 2000 g. He subsequently died of respiratory failure on day 3 of life.

CONCLUSION

Although still rare, the increasing incidence of abdominal pregnancies in both developed and developing countries mandates awareness of this diagnosis, particularly in pregnant or postpartum women presenting with abdominal pain.

Uptake and release of radiolabelled monoclonal antibody Po66 by multicellular aggregates obtained from a lung squamous carcinoma cell line

Po66, a monoclonal antibody (MAb) directed against lung squamous cell carcinoma, has been shown, when injected intravenously, to be retained for a long time in tumors. This property encouraged trials to use Po66 as an agent of metabolic radiotherapy. The suitability of multicellular spheroids to reproduce the in vivo conditions of irradiation of tumors by Po66 was investigated in the present work. Spheroids were formed from the lung carcinoma cell line SK-MES-1. They resembled morphologically small carcinoma nodules with desmosome-like intercellular junctions at the periphery and a central necrotic core. The cells expressing the antigen recognized by Po66 had a heterogeneous distribution and were predominant in the outer layers of the cell aggregates. Spheroids were exposed to radiolabelled Po66. The MAb diffused slowly and reached a maximal incorporation after 4-12 hours incubation. A control unrelated antibody did not penetrate appreciably. Autohistoradiographic experiments suggested that the antibody accumulated in most cells expressing the antigen. The rate of MAb release from the spheroids was very low (T 1/2 = 163 h). Taken together, the data indicate that spheroids might be a relevant model to investigate the parameters controlling Po66-mediated immunoradiotherapy.

111Indium-F(ab)'2-NCA 102 monoclonal antibody: in vitro study of a specific agent for the detection of inflammatory foci

A new antigranulocyte antibody was evaluated in vitro for the detection of inflammatory foci in man. The specificity for polymorphonuclear cells (PMN) of NCA 102, an anti-NCA 95 monoclonal IgG1, was determined with immunohistochemical and cytofluorometrical tests. Its affinity, assessed by Scatchard analysis, was 1.1 x 10(9) L/mol and the number of epitopes per granulocyte reached about 10(5). The biological properties of PMNs incubated with NCA 102 were not inhibited even when coupled with DTPA. A F(ab)'2 fragment was radiolabelled with 111Indium and incubated in the presence of whole blood. More than 65% radioactivity was selectively taken up by the PMN population. These findings indicated that NCA 102 antibody is suitable for sepsis detection.

Effect of an anti-HLA class I monoclonal antibody on the antigenic and transcriptional expression of HLA class I genes in U937 cells

The phenomenon of antigenic modulation was studied in the histiocytic lymphoma line U937. A redistribution of cell surface HLA antigen after incubation of U937 cells with the monomorphic anti-HLA class I monoclonal antibody W6/32 was demonstrated by immunofluorescence analysis. As assessed by hybridization of RNA obtained from W6/32-treated U937 cells with a probe corresponding to the alpha 3 domain of HLA Cw3, prolonged W6/32 incubation (24 to 72 hours) induced a decrease in HLA class I transcript abundance. This decrease was about 25% as compared with untreated control cells. These data indicate that W6/32 incubation can induce changes in HLA class I gene expression not only at the antigenic but also at the transcriptional level. Possible implications for the molecular basis of antigenic modulation are discussed.

Monoclonal antibody AP-282 recognizes a marker for human polymorphonuclear granules

Hybridoma AP-282 was produced by fusing mouse plasmacytoma cells with splenocytes of mice immunized against purified human polymorphonuclear cells. The secreted monoclonal antibody (MAb), AP-282, a mouse IgG1, was found to react strongly with all neutrophilic granulocytes, their bone marrow precursors, weakly with blood monocytes and not with eosinophils. The antigen was resistant to formalin fixation but was destroyed by exposure to fixatives containing acetic acid. Using the APAAP technique, antibody AP-282 strongly labelled neutrophils on sections of frozen cut or paraffin embedded tissues. No staining was seen of non hematopoietic tissues. AP-282 recognized an internal antigen associated to cytoplasmic granules. Chemical investigations on dot blots of whole or of purified cellular extracts indicated that the antigen idenfied by MAb AP-282 was different from those recognized by usual antigranulocyte antibodies, i.e. myeloperoxidase, elastase, cathepsin G and lactoferrin. Thus, antibody AP-282 constitutes a new cytoplasmic marker of neutrophils.

Activation of mouse macrophages by muramyl dipeptide coupled with an anti-macrophage monoclonal antibody

A rat IgG2a monoclonal antibody (mAb3A33) directed against the mouse Mac-1 antigen was conjugated with muramyl dipeptide (MDP) by using an intermediate polymer; under such conditions 75 MDP molecules were bound to one antibody molecule. A poly(L-lysine) polymer substituted with muramyl dipeptide and 3-(2-pyridyldithio)propionyl residues were prepared, the remaining lysine epsilon-amino groups were acylated with D-gluconolactone, leading to a neutral polymer; then a few polymer conjugates were coupled to mAb3A33 via a disulfide bridge. The binding capacity of the monoclonal antibody was preserved after conjugation with MDP-polymer molecules. Mouse peritoneal macrophages, incubated for 24 h with MDP-mAb3A33 conjugate became cytostatic against P815 mastocytoma cells, whereas unconjugated mAb3A33 and MDP-bound to a nonspecific rat IgG2a were ineffective. An enhancement of the cytostatic activity induced by MDP-mAb3A33 conjugate was obtained in the presence of gamma-IFN. These results show that several tens of MDP molecules can be linked to a macrophage-specific monoclonal antibody by using a neutral intermediate polymer without impairing the binding antibody capacity and that this type of MDP conjugate can efficiently activate macrophages and therefore could be the basis of the development of new antitumor therapy.

Monoclonal antibody AMH152 reacts with human monocytes in culture and with inflammatory macrophages

Monoclonal antibodies (mAb) raised against human peritoneal macrophages were selected for their non-reactivity with freshly sampled blood cells. One of these mAb, AMH152, initially non-reactive, bound to monocytes after 18 h of culture, a property which was not shared by an unrelated antibody of the same isotype (IgG1). The induction of the expression of the antigen detected by AMH152 on monocytes in culture was not influenced by the addition of serum or by the substrate used, plastic that favoured adhesion or teflon bags. Overnight incubation at 4 degrees C in adhesion conditions did not enable antigen expression. A 1-h treatment with phorbol myristate acetate or formyl-methionyl-leucyl-phenylalanine did not increase AMH152 binding. Culturing monocytes with cycloheximide tended to inhibit antigen expression. These observations suggested that antigen expression represents an active phenomenon, requiring protein synthesis. The antigen recognized by mAb AMH152 could be visualized on sections of formalin-fixed and paraffin-embedded tissues. Macrophages of healthy lymphoid organs and tissues that expressed CD68 antigen failed to bind AMH152. In contrast, chronic inflammatory lesions, like those of sarcoidosis, tuberculosis and cat scratch disease, contained epithelioid and multinucleated giant cells that reacted with AMH152. In serous exudates of cancer metastases, 10-40% of macrophages were also stained. The antigenic material was essentially present at the cell periphery. Thus, mAb AMH152 recognized a surface antigen, detectable on paraffin-embedded tissue sections, and which accompanied differentiation of monocytes into inflammatory cells. The expression of this antigen on monocytes in culture suggests that these cells underwent an activation process, even when maintained for some hours in teflon bags and in a serum-free medium.