Binding Affinity, Selectivity, and Pharmacokinetics of the Oxytocin Receptor Antagonist L-368,899 in the Coyote (Canis latrans)

L-368,899 is a selective small-molecule oxytocin receptor (OXTR) antagonist originally developed in the 1990s to prevent preterm labor. Although its utility for that purpose was limited, L-368,899 is now one of the most commonly used drugs in animal research for the selective blockade of neural OXTR after peripheral delivery. A growing number of rodent and primate studies have used L-368,899 to evaluate whether certain behaviors are oxytocin dependent. These studies have improved our understanding of oxytocin's function in the brains of rodents and monkeys, but very little work has been done in other mammals, and only a single paper in macaques has provided any evidence that L-368,899 can be detected in the CNS after peripheral delivery. The current study sought to extend those findings in a novel species: coyotes ( Canis latrans ). Coyotes are ubiquitous North American canids that form long-term monogamous pair-bonds. Although monogamy is rare in rodents and primates, all wild canid species studied to date exhibit social monogamy. Coyotes are therefore an excellent model organism for the study of oxytocin and social bonds. Our goal was to determine whether L-368,899 is a viable candidate for future use in behavioral studies in coyotes. We used captive coyotes at the USDA National Wildlife Research Center's Predator Research Facility to evaluate the pharmacokinetics of L-368,899 in blood and CSF during a 90-min time course after intramuscular injection. We then characterized the binding affinity and selectivity of L-368,899 to coyote OXTR and the structurally similar vasopressin 1a receptor. We found that L-368,899 peaked in CSF at 15 to 30 min after intramuscular injection and slowly accumulated in blood. L-368,899 was 40 times more selective for OXTR than vasopressin 1a receptors and bound to the coyote OXTR with an affinity of 12 nM. These features of L-368,899 support its utility in future studies to probe the oxytocin system of coyotes.

Can a traditional partner preference test quantify monogamous behavior in captive coyotes?

Social monogamy is a unique social system exhibited by only 3-5% of mammalian taxa; however, all wild canid species exhibit this social system. Despite the high prevalence of social monogamy among canids, little is known about how they form selective social attachment relationships among non-kin. Thus, we aimed to quantify monogamous behavior in a highly ubiquitous canid, the coyote (Canis latrans). We adapted the three-chambered partner preference test, which was originally developed for prairie voles (Microtus ochrogaster), to assess social preference in mated pairs of captive coyotes at the USDA Predator Research Facility. We quantified monogamy-related behaviors, such as time spent in spatial proximity to a pair-mate versus a stranger. Our behavioral ethogram also included visual seeking, olfactory investigations, ears down, scent marking, and affiliative behavior. Test subjects showed significantly greater affiliative behavior toward their partner than toward a stranger. However, there was extremely high variability both within and between coyote pairs across behavioral measures. These data suggest the need for larger sample sizes when working with species with high individual variability, as well as the need for species- and facility-specific modifications to this testing paradigm and/or ethogram to better adapt it from its laboratory and rodent-based origins.

EXAMINING THE IMPACT OF NEUROIMMUNE DYSREGULATION ON SOCIAL BEHAVIOR OF MALE AND FEMALE JUVENILE RATS

Many individuals diagnosed with neuropsychiatric disorders, such as autism, attention-deficit/hyperactivity disorder, schizophrenia, and social anxiety disorder, all share a common dimension of aberrant social behavior. Epidemiological data indicate that adverse environmental factors contribute to the risk for neurodevelopmental disorders, including those associated with aberrant social behavior. Early-life exposure to infectious pathogens is one of those adverse environmental factors, suggesting that activation of the immune system during early development may contribute to disease pathology associated with altered social behavior. In the current project, we examined the impact of neonatal infection, with or without juvenile immune activation, on the expression of juvenile social behavior and on the expression of inflammatory cytokines and microglial signaling molecules in the juvenile rat brain. The outcomes of these experiments revealed that neonatal infection significantly decreased juvenile social interaction, but significantly increased juvenile play behavior in male and female rats. Moreover, neonatal infection alone, juvenile immune activation alone, and neonatal infection plus juvenile immune activation all significantly impaired social recognition in juvenile male rats. Juvenile female rats (including controls) failed to demonstrate social recognition as measured in our three-chamber social recognition test. Taken together, the behavioral and molecular data presented here support the sensitivity of the developing brain to immune activation, particularly in the expression of age-appropriate social behaviors. These data warrant the design of additional studies to examine the mechanistic relationship between early-life immune activation and aberrant social behavior to develop novel as well as modify existing therapeutic targets and preventative measures to help those who display aberrant social behavior.

Sex- and region-specific differences in microglia phenotype and characterization of the peripheral immune response following early-life infection in neonatal male and female rats

Early-life infection has been shown to have profound effects on the brain and behavior across the lifespan, a phenomenon termed "early-life programming". Indeed, many neuropsychiatric disorders begin or have their origins early in life and have been linked to early-life immune activation (e.g. autism, ADHD, and schizophrenia). Furthermore, many of these disorders show a robust sex bias, with males having a higher risk of developing early-onset neurodevelopmental disorders. The concept of early-life programming is now well established, however, it is still unclear how such effects are initiated and then maintained across time to produce such a phenomenon. To begin to address this question, we examined changes in microglia, the immune cells of the brain, and peripheral immune cells in the hours immediately following early-life infection in male and female rats. We found that males showed a significant decrease in BDNF expression and females showed a significant increase in IL-6 expression in the cerebellum following E.coli infection on postnatal day 4; however, for most cytokines examined in the brain and in the periphery we were unable to identify any sex differences in the immune response, at least at the time points examined. Instead, neonatal infection with E.coli increased the expression of a number of cytokines in the brain of both males and females similarly including TNF-α, IL-1β, and CD11b (a marker of microglia activation) in the hippocampus and, in the spleen, TNF-α and IL-1β. We also found that protein levels of GRO-KC, MIP-1a, MCP1, IP-10, TNF-α, and IL-10 were elevated 8-hours postinfection, but this response was resolved by 24-hours. Lastly, we found that males have more thin microglia than females on P5, however, neonatal infection had no effect on any of the microglia morphologies we examined. These data show that sex differences in the acute immune response to neonatal infection are likely gene, region, and even time dependent. Future research should consider these factors in order to develop a comprehensive understanding of the immune response in males and females as these changes are likely the initiating agents that lead to the long-term, and often sex-specific, effects of early-life infection.

Sex Differences in the Neuroimmune System

While sex differences in the peripheral immune response have been studied extensively, sex differences in the neuroimmune response, including glial activation and associated cytokine production in the brain, is a recently emerging field. Advances in our understanding of sex differences in the neuroimmune response have important implications for understanding how neural circuits are shaped during early brain development, how activation of the immune system may impact cognitive function and behavior, and how inflammation may be associated with the risk of mental health disorders that have strong sex-biases. The goal of this mini review is to highlight recent work in the field of sex differences in neuroimmune function, with a particular focus on how microglia function is influenced by age and sex hormone exposure.

Sexual Differentiation and Sex Differences in Neural Development

Sex determination occurs at the moment of conception, as a result of XX or XY chromosome pairing. From that point, the body undergoes the process of sexual differentiation, inducing the development of physical characteristics that are easily distinguishable between the sexes and are often reflected in one's physical appearance and gender identity. Although less apparent, the brain also undergoes sexual differentiation. Sex differences in the brain are organized during a critical period of neural development and have an instrumental role in determining the physiology and behavior of an individual throughout the lifespan. Understanding the extent of sex differences in neurodevelopment also influences our understanding of the potential risk for a number of neurodevelopmental, neurological, and mental health disorders that exhibit strong sex biases. Advances made in our understanding of sexually dimorphic brain nuclei, sex differences in neural cell communication, and sex differences in the communication between the brain and peripheral organs are all research fields that have provided valuable information related to the physiological and behavioral outcomes of sex differences in brain development. More recently, investigations into the impact of epigenetic mechanisms on sexual differentiation of the brain have indicated that changes in gene expression, via epigenetic modifications, also contribute to sexual differentiation of the developing brain. Still, there are a number of important questions and ideas that have arisen from our current understanding of sex differences in neurodevelopmental processes that necessitate more time and attention in this field.

Activation of neonatal microglia can be influenced by other neural cells

During development, microglial progenitor cells migrate into the brain from the periphery, a process critical to the maturation of the developing brain. Although they perform functions similar to mature, adult microglia, immature microglia are distinct from mature microglia. Activation of immature microglia, via an early-life immune challenge, can lead to persistent changes in microglial function, resulting in long-term neuronal and cognitive dysfunction. Early-life immune activation is associated with multiple neurodevelopmental disorders, including autism, ADHD, schizophrenia, and cerebral palsy - disorders with known or suspected immune etiologies, and strong sex biases for males. Activation of immature microglia requires further examination to determine its potential role in these neurodevelopmental disorders. More work is also necessary to better understand the relationship between developing microglia and other developing neural cells during this critical period of development. Thus, we treated freshly isolated, sex-specific microglia from the rat hippocampus with lipopolysaccharide (LPS) on P4, in either the presence or absence of other neural cells. Mixed and microglial-specific cultures were analyzed for inflammatory gene expression to determine whether immature microglia exhibited a sex-specific response to immune activation, and if the presence of all other neural cells influenced that response. We found that the microglial response to an LPS-induced immune activation differed depending on the presence of other neural cells in the culture. We found very few sex differences in the cytokine response, except that the microglial expression of IL-6 following immune activation was more robust in male microglia that were in the presence of other neural cells than female microglia in the same condition.

Heterogeneity and breadth of host antibody response to KSHV infection demonstrated by systematic analysis of the KSHV proteome

The Kaposi sarcoma associated herpesvirus (KSHV) genome encodes more than 85 open reading frames (ORFs). Serological evaluation of KSHV infection now generally relies on reactivity to just one latent and/or one lytic protein (commonly ORF73 and K8.1). Most of the other polypeptides encoded by the virus have unknown antigenic profiles. We have systematically expressed and purified products from 72 KSHV ORFs in recombinant systems and analyzed seroreactivity in US patients with KSHV-associated malignancies, and US blood donors (low KSHV seroprevalence population). We identified several KSHV proteins (ORF38, ORF61, ORF59 and K5) that elicited significant responses in individuals with KSHV-associated diseases. In these patients, patterns of reactivity were heterogeneous; however, HIV infection appeared to be associated with breadth and intensity of serological responses. Improved antigenic characterization of additional ORFs may increase the sensitivity of serologic assays, lead to more rapid progresses in understanding immune responses to KSHV, and allow for better comprehension of the natural history of KSHV infection. To this end, we have developed a bead-based multiplex assay detecting antibodies to six KSHV antigens.

[Occupational stress and job insecurity in men working in a university]

77 men working in a university were investigated. Trait and state anxiety were determined by STAI I and STAI II; job strain (job demand/decision latitude), social support and job insecurity were analysed by a 46 item Karasek's questionnaire and subjective symptoms by a 12 item test. The employees of a library (mean age 49 years), in contact with students, showed significantly higher values of job strain, STAI I, STAI II and subjective symptoms than a control group of employees with similar age. Young employees and sanitary staff with temporary employment showed higher level of job insecurity than control subjects with stable position. Blood cytotoxic activity (reported in another study) was significantly lower in the old employees with job strain or in the young employees with job insecurity (but not in the sanitary staff) than in the controls; this demonstrates that not only occupational stress but also job insecurity may play an important role in affecting the health status.

[Anxiety, job stress and job insecurity among teachers with indefinite or definite time contract]

Object of this study was the occupational stress of 336 teachers (276 women and 60 men) with stable or temporary employment in schools of Pescara, town of Central Italy. The levels of anxiety were determined by STAI and STAI II, those of job strain", "job insecurity" and social support by the Karasek's questionnaire, and the perception of subjective symptoms by a 12 item test. There were no significant differences depending on the type of school. The women with temporary contract showed higher levels of "job insecurity", while the men with temporary job showed also higher values of STAI I and STAI II. The scores of anxiety of the women were positively correlated with "job strain", "job insecurity" and perception of subjective symptoms and negatively with social support, while the only correlations of STAI I and STAI II of men showing statistical significance of men was that with "job insecurity. Job strain was negatively correlated with the perception of symptoms both in women and men. These results evidence differences in the occupational stress of men and women; in particular, job insecurity may enhance anxiety in men.

Depressive disorders and personality variables in HIV positive and negative intravenous drug-users

BACKGROUND

Only a few reports investigated the prevalence of depression in intravenous drug-users with HIV infection, including both asymptomatic and symptomatic subjects. In the same group, the association of depression and personality diagnoses was also poorly researched.

METHODS

A consecutive sample of intravenous drug-users was collected from patients admitted to an infectious disease clinic, another random sample was taken from out-patients attending a methadone maintenance treatment program. Subjects were first screened with the Hospital Anxiety and Depression Scale, and then all positive subjects were evaluated with the Composite International Diagnostic Interview. Depression was diagnosed according to DSM-IIIR. In-patients were also given a structured personality inventory (Karolinska Psychodynamic Profile).

RESULTS

HIV-positive patients had a high rate of depression (major depression 36.2%, dysthymic disorder 7.1%) when compared to HIV-negatives (15.7 and 3.9%, respectively). In-patients had the highest rate of depression, irrespective of HIV clinical staging. A personality disorder was diagnosed in 36% of the sample, but these subjects were no more significantly depressed.

LIMITATIONS

Poor detection of depression by the admitting physician may have led to selective hospitalization of patients with both HIV and mood disorder. The composition of the sample may also be biased by the help-seeking behavior of HIV patients who are also depressed.

CONCLUSION

Physicians treating AIDS patients should be alerted to the high rate of depression in clinical HIV illness, in order to identify and properly treat depression.

HCV-RNA occurrence in saliva of odontoiatric HCV seropositive patients

BACKGROUND

HCV-RNA occurrence in saliva of patients suffering from C hepatitis induced to consider saliva as a possible diffusion mean of this disease.

METHODS

Saliva and blood samples from 32 C hepatitis seropositive patients, followed for odontostomatologic problems in Odontoiatric Clinic of Brescia University were obtained. In every blood and saliva sample HCV-RNA concentration was evaluated following HCV-RNA 2.0 Assay (bDNA) Quantiplex test (Chiron), in Microbiology Institute of Brescia University.

RESULTS

All patients showing HCV-RNA in serum presented virus in saliva also; two patients with negative HCV-RNA serum presented virus in saliva. In latter cases, we supposed that viral concentration in serum was under sensibility threshold of employed method.

CONCLUSIONS

Saliva appears an easily and not invasively obtainable medium for epidemiological studies on HCV diffusion in humans. Its role in C hepatitis transmission, on the contrary, has not been cleared till now.

CD11b expression identifies CD8+CD28+ T lymphocytes with phenotype and function of both naive/memory and effector cells

A previously unreported CD8(+)CD28(+)CD11b(+) T cell subset occurs in healthy individuals and expands in patients suffering from primary viral infections. In functional terms, these cells share the features of naive/memory CD8(+)CD28(+)CD11b(-) and terminally differentiated effector CD8(+)CD28(-)CD11b(+) subpopulations. Like CD28(-) cells, CD28(+)CD11b(+) lymphocytes have the ability to produce IFN-gamma, to express perforin granules in vivo, and to exert a potent cytolytic activity. Moreover, these cells can respond to chemotactic stimuli and can efficiently cross the endothelial barrier. In contrast, like their CD11b(-) counterpart, they still produce IL-2 and retain the ability to proliferate following mitogenic stimuli. The same CD28(+)CD11b(+) subpopulation detected in vivo could be generated by culturing naive CD28(+)CD11b(-) cells in the presence of mitogenic stimuli following the acquisition of a CD45RO(+) memory phenotype. Considering both phenotypic and functional properties, we argue that this subset may therefore constitute an intermediate phenotype in the process of CD8(+) T cell differentiation and that the CD11b marker expression can distinguish between memory- and effector-type T cells in the human CD8(+)CD28(+) T cell subset.

Usefulness of genus-specific PCR and Southern blot species-specific hybridization for the detection of imported malaria cases in Italy

A PCR method involving a genus-specific oligonucleotides set and Southern blot hybridization with four species-specific probes to P. falciparum, P. vivax, P. malariae and P. ovale was evaluated for the detection of malaria parasites in blood samples from 101 patients with clinically suspect malaria infection imported to Italy. Plasmodium falciparum was the main species detected. As determined by microscopy, 53 (52.4%) patients had malaria and of these: 40 (75.5%) were infected with P. falciparum; 7 (13.2%) with P. vivax; 1 (1.9%) with P. ovale; 3 (5.7%) with P. malariae; 1 (1.9%) with P. vivax or P. ovale; and 1 (1.9%) with P. falciparum or P. vivax. Ninety-seven out 101 blood samples were submitted to ParaSight-F test which showed a sensitivity of 94.73%, and a specificity of 93.22%, as compared to microscopy. The PCR assay using the genus-specific oligonucleotide primer set (pg-PCR) was able to detect 53 (52.4%) infections and showed a sensitivity of 100% and a specificity of 100%, when compared to microscopy. The parasite species were identified by Southern blot hybridization using species-specific probes and 40 (75.5%) samples were P. falciparum positive, 5 (9.4%) P. vivax positive, 4 (7.5%) P. ovale positive, and 2 (3.8%) P. malariae positive. When the Southern blot results were compared to those of blood-film diagnosis, we observed some disagreement. In particular, compared to Southern blot, microscopy underestimated P. ovale infection; blood film analysis recognised only 1 P. ovale sample, whereas Southern blot recognised 4 P. ovale positive samples (by microscopy, 2 of these were detected as P. vivax, 1 as P. ovale or P. vivax, and the other as P. falciparum or P. vivax). Southern blot hybridization was unable to identify one P. falciparum and one P. vivax positive case detected by microscopy. We also plan to use a reference nested-PCR assay to clarify the disagreement observed between microscopy and Southern blot hybridization.

Identification of Mycobacterium xenopi by gas chromatography

For the purposes of the following study we cultured 32 strains of Mycobacterium xenopi isolated from clinical specimens and several strains of other slowly growing mycobacteria. The cultures were grown in liquid medium and then analysed--after saponification, methylation, extraction with organic solvent and washing of the organic phase--using a highly sensitive manual gas-liquid chromatographic assay for the determination of secondary alcohol 2-OH-docosanol. The percentage of this compound was compared with that previously measured in strains of Mycobacterium xenopi grown on solid medium. The presence of this specific alcohol was always apparent, even though its quantity was lower than that obtained by growing mycobacteria on solid medium. The absence of interference peaks around the compound was checked by analyzing strains of other slowly growing mycobacteria in the same conditions.

A comparison of Legionella pneumophila occurrence in hot water tanks and instantaneous devices in domestic, nosocomial, and community environments

The aim of this study was to compare the occurrence of L. pneumophila in hot water samples from hot water tanks and instantaneous devices. Tanks and devices were all operated by heat exchangers employed in the town's district heating system. Thirty-six out of 171 (21%) hot water samples tested positive for L. pneumophila isolation, with 14.6% belonging to serogroup 1 and 6.4% to serogroups 2-14. The proportion of L. pneumophila detected in hot water reservoirs (30%) was higher than that observed in hot water instantaneous devices (6.2%). Differences in L. pneumophila isolation reflected different temperatures registered at the faucet: </=50 degrees C for hot water from reservoir devices, and >60 degrees C for hot water from instantaneous devices. These data emphasize the need to control temperature in hot water distribution devices, thus inhibiting the formation of biofilm and L. pneumophila colonization.

Evaluation of OptiMAL Assay test to detect imported malaria in Italy

This study evaluated a newly developed rapid malaria diagnostic test, OptiMAL Assay, to detect "Plasmodium falciparum malaria" and "non Plasmodium falciparum malaria" in blood samples from 139 individuals with a presumptive clinical diagnosis of imported malaria in Italy. OptiMAL Assay utilizes a dipstick coated with monoclonal antibodies against the intracellular metabolic enzyme, plasmodium Lactate Dehydrogenase (pLDH) present in and released from parasite-infected erythrocytes. Blood samples from 56 cases out of 139 were found "Plasmodium falciparum malaria" positive by microscopy; with these samples OptiMAL Assay and the ParaSight-F test, which is a kit detecting the P. falciparum histidin-rich protein 2 (HRP-2), showed an overall sensitivity of 83% and 94%, respectively, in comparison with microscopy. Parasitemia levels tested in the 56 P. falciparum positive blood samples by microscopy ranged from <0.004% to 20%. A correlation between sensitivity and parasitemia was evident and OptiMAL Assay and ParaSight-F test were more sensitive (96-100%; 100%) with samples with 0.1%-20% levels of parasitemia, while proved less sensitive (0-44%; 50-88%) with <0.004-0.01% levels of parasitemia.

Phenotypic and functional characteristics of tumour-derived microvascular endothelial cells

We recently developed a method for the isolation and purification of tumour-derived endothelium. In this study the phenotypic and functional properties of human tumour-derived microvascular endothelial cells (TdMEC) were examined. Endothelium obtained from human adrenal gland specimens (HAMEC) was used as a reference microvascular endothelial cell population. TdMEC formed a confluent monolayer with the typical morphological appearance of endothelium and were positive for endothelial markers such as Ulex-1 lectin, CD31 antigen, von Willebrand Factor and VE-cadherin. The addition of acidic Fibroblast Growth Factor (aFGF), basic FGF (bFGF) or Vascular Endothelial Growth Factor (VEGF) substantially improved proliferation of TdMEC; and kidney carcinoma derived endothelial cells were more responsive to FGFs, whereas glioblastoma derived endothelial cells greatly responded to VEGF TdMEC expressed high levels of the VEGF receptors, KDR/flk-1 and Flt-1, as shown by northern blot analysis. TdMEC expressed the adhesion molecules ICAM-1, VCAM-1 and E-selectin that could be further increased by exposing TdMEC culture to interleukin-1. All the TdMEC expressed interleukin-8 mRNA. These findings show that TdMEC in vitro maintain several of the features described for microvasculature. Thus, TdMEC represent a useful tool to study markers for tumor vasculature.

Expansion of rare CD8+ CD28- CD11b- T cells with impaired effector functions in HIV-1-infected patients

The decline in the number of CD4+ T cells in HIV-1-infected patients is known to be related to the increased number of CD8+CD28- T cells. In this paper, we show that CD8+CD28- T cells from HIV-positive patients have an impaired capability to interact with human endothelial cells. This is due to the dramatic expansion, within this subset, of rare CD11b- cells lacking cell-cell adhesion functions. In 50 HIV-positive patients, 19.5% +/- 6.5% of all T cells were CD8+CD28-CD11b-, whereas only 0.8% +/- 0.4% of all T cells from healthy donors showed this uncommon phenotype. The percentage of circulating CD8+CD28-CD11b- T cells was strongly related to the percentage of CD4+ T cells (r = -0.82). This population is peculiar in terms of HIV infection and was found to possess some characteristics associated with effector functions but its cytotoxic properties were impaired. The percentage of target cells lysed by CD8+CD28-CD11b- was significantly lower than that of cells lysed by its CD11b- counterpart (p <.05) both at low (5:1) or at relatively high (20:1) effector/target ratios. CD8+CD28-CD11b- T cells, which lack the ability to interact with endothelial cells, are likely to accumulate and persist in circulation. The biologic properties of CD8+CD28-CD11b- T cells suggest that these cells might be endstage or aberrant differentiated effector cells. Lack of cell-cell adhesion and impaired cytolytic functions favor the hypothesis of a role for CD8+CD28-CD11b- T cells in the development of immunodeficiency.

Search for malaria parasites by PCR and Southern blot in patients with imported malaria in Italy

The present study evaluates the sensitivity, specificity and usefulness of a PCR method with Southern blot hybridization to detect malaria parasites in blood samples from subjects with a suspect clinical diagnosis of malaria imported to Italy. Plasmodia were detected by PCR using a genus-specific primer-set corresponding to the sequences common to P. falciparum, P. vivax, P. malariae and P. ovale, as described by Arai (Arai et al., Nucleosides Nucleotides, 1994, 13, 1363-1364) and Kimura (Kimura et al., Journal of Clinical Microbiology, 1995, 33, 2342-2346). In addition, four distinct tandemly repetitive species-specific probes, described by Kawai (Kawai et al., Analytical Biochimestry, 1993, 209, 63-69), were synthesized to specifically detect the four malaria parasites species by Southern blot hybridization. Fifteen blood samples from 12 patients (7 with malaria) were tested and the genus-specific PCR method showed a sensitivity of 100% and a specificity of 100%, when compared to microscopy, in detecting malaria parasites in the tested blood samples. Fourteen samples (nine were positive and five negative by PCR) were confirmed by Southern blot, whereas only one P. vivax positive sample was not hybridized with the species-specific probes. We conclude that this PCR method with Southern blot hybridization may be useful in detecting malaria parasites in patients with malaria imported to Italy.

Liver damage and kinetics of hepatitis C virus and human immunodeficiency virus replication during the early phases of combination antiretroviral treatment

In order to assess the relationship between human immunodeficiency virus (HIV) RNA, hepatitis C virus (HCV) RNA, CD4, CD8, and liver enzymes during combination antiretroviral therapy, these parameters were measured in 12 HIV-HCV-coinfected patients (who were naive for antiretrovirals) on the day before and 3, 7, 14, 28, 56, and 84 days after initiating the following treatments: stavudine and lamivudine in all patients, indinavir in 6 patients, and nevirapine in 6 patients. HIV RNA declined rapidly, CD4 cells increased slowly, and CD8 cells and liver enzymes were stable. HCV RNA showed a transient significant increase at days 14 and 21 (7.33+/-0.16 [mean +/- SE] and 7.29+/-0.2 log copies/mL vs. 7+/-0.2 log copies/mL at baseline; P<.05). These changes were similar in both treatment groups. A 2-fold alanine aminotransferase increase was observed in 4 of 12 patients; 4 of 4 patients showed increased HCV RNA. The relationship between HCV RNA increase and HIV RNA decrease indicates virus-virus interference. An HCV RNA increase may cause significant liver damage only in a minority of patients.

Differential production of IFN-gamma, analyzed at the single-cell level, by specific subsets of human NK and T cells from healthy and HIV(+) subjects

BACKGROUND

Interferon gamma is a cytokine that plays a central role in immunity, and is physiologically secreted by T and NK cells under appropriate stimuli during the immune response. By means of flow cytometry, we performed a single cell analysis of interferon gamma producing NK cells and their surface phenotype in normal and HIV(+) individuals that show several defects of cytokine production and cellular immunity.

METHODS

PBMC or purified NK cells were stimulated for 1-12 h with PMA/ionomycin in the presence of monensin, subsequently stained for surface CD56 and CD3 or CD8, and for intracytoplasmic IFN-gamma, and analysed by flow cytometry.

RESULTS

Our results show that CD56(+) NK cells are more efficient interferon gamma producers than T cells. Moreover, within the CD56(+) NK cell population, those that co-express low density CD8 are the best producers. Finally, we show that NK cells during HIV infection are more massively recruited to interferon gamma production than those from normal subjects.

CONCLUSIONS

Both in the normal and HIV(+) subjects, a higher percentage of NK cells than T cells can produce IFN-gamma although differences can be identified within the NK cells subset in terms of IFN-gamma production. The production of IFN-gamma is fully achievable in the HIV(+) subjects, which is consistent with their elevated plasmatic levels of the cytokine. The possibility that NK cells that produce interferon gamma could represent a functionally distinct population committed to the production of this cytokine, is discussed.

Increased frequency of detection of Ureaplasma urealyticum and Mycoplasma genitalium in AIDS patients without urethral symptoms

The roles of Mycoplasma genitalium and Ureaplasma urealyticum in nongonococcal urethritis are not yet well established. The aim of this study was to determine the presence of these microorganisms in the urethral tracts of 187 human immunodeficiency virus type 1 (HIV-1)-infected male patients with no clinical signs of urethritis. The results indicate that the prevalence of M. genitalium and U. urealyticum was higher in AIDS patients than in asymptomatic, HIV-1-infected patients and in healthy individuals. The high rate of mycoplasmas and ureaplasmas detected in AIDS patients, in the absence of urethritis, argues against major roles in causing disease at the urethral mucosal level for these microorganisms.

Generation of CD28- cells from long-term-stimulated CD8+CD28+ T cells: a possible mechanism accounting for the increased number of CD8+CD28- T cells in HIV-1-infected patients

According to CD28 molecule expression, CD8+ T cells can be classed as CD28bright, CD28dim, and CD28-. The CD28dim T cells were found to derive from mitogenic stimulated CD28-T cells but also from CD28bright T cells through a mechanism of CD28 down-modulation. Moreover, after prolonged in vitro interleukin-2 stimulation, clonal CD28bright, cells showed a CD28dim expression before further evolution to a stable CD28-phenotype. This loss was concomitant with the disappearance of CD28 mRNA. A study of the cytokine production pattern revealed that CD28dim and CD28- T cell clones produced similar levels of type 1 and type 2 cytokines, which differed from those produced by the CD28bright T cell clones. A high percentage of CD28dim and CD28- cells, with similarities in their cytokine production pattern, were found in the blood samples of HIV-infected patients, as compared to healthy donors. The CD28 down-modulation may account for the increased number of CD8+CD28- T cells in HIV-infected patients.

Gas chromatographic assay of cellular fatty acids and alcohols for the identification of Mycobacterium species

Ten mycobacterial species obtained from 141 cultures isolated from clinical specimens were studied. The cultures were grown on solid medium and then analysed-after saponification, methylation, extraction with organic solvent and washing of the organic phase--by capillary gas-liquid chromatography for fatty acid and secondary alcohol composition. The absence of secondary alcohols was characteristic of M. genavense, M. tuberculosis and the following Mycobacterium species with specific branched-chain fatty acids allowing their direct identification: M. gordonae, M. kansasii and M. marinum. The presence of secondary alcohols was characteristic of M. avium, M. phlei, M. scrofulaceum, M. terrae and M. xenopi. In the case of M. xenopi direct identification was made possible by the presence of a specific alcohol.

Complete in vitro prosthesis endothelialization induced by artificial extracellular matrix

This report presents our research on the conditions necessary to substain optimal in vitro prosthetic endothelialization using human endothelium cultures. Human vein endothelial cells were seeded at a concentration of 3 x 10(5)/cm2 in a gelatinized Dacron patch graft coated with a commercial collagen film, using a solution of fibrin glue. Endothelium adhesion, proliferation, and survival were measured by [3H]thymidine incorporation, after 7 days of incubation. Finally, the morphology of prosthetic endothelialization was analyzed by scanning electron microscopy. We observed that the Dacron patch grafts coated with collagen film were able to promote endothelialization better than the prostheses coated with highly concentrated collagen solution or gelatin. We therefore concluded that the collagen film that supports endothelial cell adhesion and proliferation uniformly covers the entire synthetic endoluminal surface of the Dacron graft, thus preventing endothelial cell alterations induced by direct contact with the synthetic prosthetic surface.

Development of horse polyclonal antiserum inhibiting all in vitro biological functions of human IFN-gamma

Following a standard immunization protocol with recombinant human interferon-gamma (IFN-gamma), a horse polyclonal antiserum was obtained and evaluated for its ability to interfere with multiple IFN-gamma activities in vitro. Data obtained show that polyclonal horse antiserum neutralizes the antiproliferative activity of IFN-gamma, inhibits the binding of IFN-gamma to cellular receptors, and can up-regulate HLA-DR antigen expression and interfere with its antiviral activity. The broad neutralizing capacity of horse polyclonal antiserum has been assessed on cell lines which differ as to origin and sensitivity to IFN-gamma. Moreover, we observed that this antiserum could inhibit the binding of radiolabeled IFN-gamma to its cellular receptor, its subsequent internalization into the target cell, and its antiviral activity. As it is able to inhibit all the biological activities of IFN-gamma, this antiserum might provide new therapeutic approaches to diseases with evidence of activated cell-mediated immunity.

Isolation and chemoantibiotic resistance of Ureaplasma urealyticum in HIV-1 infected patients

The presence of Ureaplasma urealyticum was evaluated on 1912 vaginal and urethral swabs from HIV-1 seronegative (HIV-) inpatients (210) and outpatients (503) suffering from acute urethritis or vaginitis; asymptomatic HIV- outpatients (201); and asymptomatic HIV-1 seropositive (HIV+) inpatients (120). The study reported an increased frequency of Ureaplasma urealyticum isolates in asymptomatic HIV+ compared to asymptomatic HIV- subjects. As expected, the frequency of Ureaplasma urealyticum isolates increased in symptomatic HIV- subjects. Strains of Ureaplasma urealyticum resistant to ciprofloxacin, tetracycline and minocycline were more frequently isolated in HIV+ (34.1%) than HIV- (3.8%) subjects; on the other hand, only 1 out of 704 (0.1%) strains isolated from outpatients was resistant to ciprofloxacin. We found no association in HIV+ patients between Ureaplasma urealyticum infection and CD4 count or HIV-1 p24 antigenemia.

HIV p17 enhances lymphocyte proliferation and HIV-1 replication after binding to a human serum factor

OBJECTIVE

To analyse the role of recombinant HIV-1 protein p17 in the modulation of cell activity.

METHODS

Peripheral blood mononuclear cells (PBMC) obtained from healthy donors were cultured in the presence or absence of p17 with mitogens such as phytohaemagglutinin or interleukin-2 and their response assayed by cell proliferation. Cross-linking experiments were employed to investigate the presence of a binding between p17 and factor(s) present in human serum. An immunoenzymatic assay for p24 antigen detection was used to analyse the effect of the addition of exogenous p17 to cultures of PBMC infected with HIV-1 in vitro.

RESULTS

Purified recombinant p17 protein at a concentration of 0.25 microg/ml significantly increased the proliferation of preactivated PBMC obtained from healthy donors. This effect was obtained by binding p17 to factor(s) present in human serum and observed on both CD4+ and CD8+ T cells. Recombinant p17 also induced an increased rate of HIV-1 replication, probably due to enhanced T-cell proliferation. The activity of p17 protein was inhibited by anti-p17 antibodies generated by injecting recombinant p17 in rabbits, but not by human antibodies generated during the natural course of HIV infection.

CONCLUSION

Characterization of the human factor(s) and identification of the interacting p17 epitope(s) will improve our understanding of the mechanisms used by HIV to efficiently replicate in our organisms.

Lack of polarized type 1 or type 2 cytokine profile in asymptomatic HIV-1-infected patients during a two-year bimonthly follow-up

The production of type 1 (interferon or IFN-gamma) and type 2 (interleukin or IL-4 and IL-10) cytokines by mitogen-stimulated peripheral blood mononuclear cells (PBMCs) obtained from asymptomatic human immunodeficiency virus-seropositive (HIV+) patients untreated with any antiviral, antibacterial or antimycotic drugs, and from healthy individuals, was evaluated by quantitative ELISA. Patients who were HIV+ were characterized by the absence of abnormal cytokine production. The level of each cytokine differed among individuals in the same group with intersubject variations greater for HIV+ patients than for healthy individuals. The longitudinal evaluation of IFN-gamma, IL-4 and IL-10 production showed intrasubject variations which were particularly marked in HIV+ patients. Accordingly, HIV+ patients and, to a lesser extent, healthy individuals were characterized by a wide spectrum of possible profiles, which were confined to type 0 phenotype. In HIV+ patients no correlation was found between each cytokine level and the number of CD4+ T cells, not even in those with a falling CD4+ T-cell count and clinical symptoms.

Contribution of CD4+, CD8+CD28+, and CD8+CD28- T cells to CD3+ lymphocyte homeostasis during the natural course of HIV-1 infection

The relationship between the number of circulating CD4+ T cells and the presence of particular CD8+ T cell subsets was analyzed by flow cytometry on PBL from asymptomatic HIV-1-infected patients whose specimens were collected every 2 mo for a total period of 32 mo. Only slight variations were detected in the absolute number of lymphocytes and percentage of CD3+ lymphocytes, whereas both CD4+ and CD8+ T cell subsets showed wide intrapatient variation. Variations in the number of CD8+CD28+ cells paralleled those of the CD4+ T cell subset in each patient tested, while the presence of CD8+CD28- T cells correlated inversely with CD4+ and CD8+CD28+ T cells. These data show that changes in the number of circulating CD4+-and CD8+CD28+ T cells are strongly related to the presence of CD8+CD28- T cells in these patients. Insight into the significance of CD8+CD28- T cell expansion will allow us to understand the mechanisms and significance of the HIV-1- driven change in CD4+CD8+ T cell homeostasis and the basic immunopathology of HIV disease.

Isolation of HTLV-1 from an aggressive form of ATL in a Romanian patient not at risk of infection and with seronegative family members

We present the clinical, virological and haematochemical data of a 22 year old patient from Romania with Adult T Cell Leukaemia (ATL). Viral isolation in peripheral mononuclear blood cells (PMBC), detection of DNA sequences of HTLV-1 by Polymerase Chain Reaction (PCR) and of antibodies by Elisa and Western blot were performed. The patient does not belong to any risk group and additionally all members of her family are seronegative for HTLV-1, the aetiological agent of ATL. The role of viral infection remains open.

T cells from individuals in advanced stages of HIV-1 infection do not proliferate but express activation antigens in response to HIV-1-specific antigens

Like T cells from healthy subjects, those of HIV-1-infected patients are capable of expressing activation antigens on their surface after antigenic or mitogenic stimulation, but their proliferative activity is strongly reduced or even absent, especially in patients with advanced stages of the disease. The characteristic of expressing activation antigens in response to different stimuli in the absence of cell proliferation is shared by CD4+ and CD8+ T-cell subsets from HIV-1-infected patients. The number of T cells capable of expressing CD25 and CD71 in response to HIV-1-related antigens but not of proliferating increased significantly with the progression of the disease, but the number of T cells capable of expressing the two activation antigens in response to the classic tetanus toxoid recall antigen decreased. The higher numbers of T cells capable of responding to HIV-1-related antigens in conjunction with a reduction in the number of T cells responding to recall antigens may explain the occurrence of different infections, including opportunistic microorganisms, during the more advanced stages of HIV-1 infection. Because the increase in the number of HIV-1 antigen-responding T cells (defined by CD25 and CD71 activation antigen expression) is a characteristic of symptomatic HIV-1-infected patients, expression (by flow cytometry) of these activation antigens on T cells in response to HIV-1 antigens could be used as a new marker of disease progression.

In-vitro study of the synergy between beta-lactam antibiotics and glycopeptides against enterococci

The synergy between glycopeptides and beta-lactams was studied using different techniques such as broth macrodilution, killing curves and agar dilution combined with agar diffusion. Two glycopeptide-resistant enterococci isolated from different clinical samples were used. Results showed different effects with significant changes in MICs. Antibacterial activity was related to the concentration of glycopeptide and beta-lactam for Enterococcus faecalis 8253, while for Enterococcus faecium 8072 a paradoxical effect was observed. With this strain, the best synergic effect was detected at teicoplanin concentrations of 1-4 mg/L, but antibacterial activity was reduced at concentrations of 8, 16 and 32 mg/L. No synergic effect was observed with vancomycin. The combination of agar dilution with agar diffusion techniques may constitute a simple method for routine detection of synergic effects between glycopeptides and beta-lactams.

Flow cytometric analysis of activation markers on stimulated T cells and their correlation with cell proliferation

The expression of activation antigens, namely CD25, CD69, CD71, and HLA-DR on T cells from 15 healthy individuals stimulated with different mitogens and specific antigens was evaluated by immunofluorescence assay and flow cytometric analysis and compared with cell proliferation as a function of [3H]thymidine incorporation. CD69 was the earliest expressed antigen on stimulated cells, while HLA-DR was the latest. Regardless of the stimulus used, lymphocytes expressing CD25 and CD71 were always more numerous than cells expressing CD69 and HLA-DR. Variations in the proportion of CD4+ and CD8+ T cells expressing each activation marker were observed with different antigenic stimuli. The expression of each activation marker showed overall agreement with the [3H]thymidine incorporation assay in discriminating between positive and negative immune response. However, no correlation was observed between the percentage of CD25-, CD69-, CD71-, and HLA-DR-positive T cells and the amount of [3H]thymidine incorporation. Moreover, low doses of mitogens and antigens as well as short time of stimulation were sufficient to induce T cells to express activation antigens but not to proliferate. Our data show that results obtained by flow cytometry and [3H]thymidine incorporation may differ qualitatively, at least under certain conditions; this suggests that the 2 assays are complementary, and when combined, may gives a clearer understanding of events leading to efficient cell-mediated immune response.

Natural antibodies to interferon-gamma

Natural antibodies to interferon (IFN)-gamma were detected in the serum of virus-infected patients and also, at a low titre, in the serum of healthy subjects. The increased titre of antibodies to IFN-gamma in the sera of virus-infected patients, and its decrease with clinical resolution, indicate that these antibodies are related to viral infection and probably reflect IFN-gamma production as a result of antigenic stimulation in vivo. Natural antibodies to IFN-gamma were affinity purified and studied for their capability to interfere in vitro with the multiple activities of the lymphokine. Data obtained show that these human anti-IFN-gamma antibodies have no inhibitory effect on the antiviral and antiproliferative activity of IFN-gamma and do not interfere with the binding of the lymphokine to its specific cell receptor. Instead, they can inhibit the expression of HLA-DR antigens induced by IFN-gamma on U937 cells and interfere, in mixed lymphocyte culture, with the proliferation of lymphocytes and the generation of cytotoxic lymphocytes. Experiments in animal models suggest that natural antibodies to IFN-gamma may have a role in the immunoregulatory process limiting the intensity and/or duration of immune response. As they can interfere only with the immunomodulating activities of IFN-gamma, these antibodies might open up new therapeutic approaches to diseases with evidence of activated cell-mediated immunity.

Heat-killed Bacillus subtilis inhibits T-cell proliferative response to mitogens and recall antigens

Heat-killed vegetative forms of Bacillus subtilis were found to impair considerably the capacity of human T-lymphocytes to secrete interleukin-2 (IL-2) and to proliferate (in terms of [3H]thymidine incorporation) after phytohaemagglutinin (PHA) stimulation. B. subtilis was also found to interfere with T-cell proliferation induced by concanavalin A (Con A) and the recall antigen tetanus toxoid (TT). The suppressive activity was dependent on bacterial concentration, and was not ascribed to mitogen, medium-nutrient absorption or cell killing. Moreover, B. subtilis did not interfere with mitogen-induced IL-2 receptor expression on the T-cell surface. On the other hand, B. subtilis did not interfere with T-cell proliferation induced by phorbol myristate acetate (PMA) and ionomycin stimulation. All data obtained suggest the binding of B. subtilis subcomponents to- or very close to-the T-cell receptor (TCR). Identification and purification of the basic structure(s) or component(s) of B. subtilis with TCR antagonist activity in vitro will help to exploit different aspects of T-cell activity and development, and possibly, will provide a means of specific control or modification of the immune response.

Interferences of urinary tract infection in the measurement of urinary nitrous oxide

OBJECTIVES

To investigate the effective role of micro-organisms in producing N2O.

METHODS

The N2O in either urine samples inoculated with 24 microbial strains or urine samples from patients with urinary tract infections were measured.

RESULTS

Gram negative bacilli generally produced high amounts of nitrous oxide (N2O), whereas Gram positive cocci and yeasts did not. The production of N2O depends on the incubation time and follows exponential kinetics, reaching a plateau at 48 hours. Furthermore, the results of urinocultures agreed well with N2O concentrations found in urine samples: samples negative for bacteria were found to contain very low concentrations of N2O whereas those positive--for example, for Enterobacteriaceae--gave highest N2O values.

CONCLUSION

The urinary tract infections caused by Gram negative bacilli are important confounding factors in biological monitoring practices of exposure to inhalation anaesthetics. The current methods adopted to avoid these factors (urine acidification, storage of samples at 4 degrees C) are not good enough because of the relative acid tolerance of some strains and the production of N2O directly into the bladder.

Detection of Mycoplasma genitalium from urethral swabs of human immunodeficiency virus-infected patients

Mycoplasma have been suggested as co-factors in the pathogenesis of acquired immune deficiency syndrome (AIDS). The prevalence of urethral infection by Mycoplasma genitalium was determined by polymerase chain reaction (PCR) with urethral swabs from 35 HIV-infected patients at different stages of the disease (all of them were heterosexual men). M genitalium was detected in 2 out of 19 non-AIDS (stage A and B) patients and in a similar proportion (1 out of 14; 7.1%) of samples from healthy individuals. A dramatic increase in the frequency of M. genitalium detection was observed in samples of AIDS (stage C) patients. In fact, 9 out of 16 (56.2%) specimens tested positive by PCR. We found no association in AIDS patients between M. genitalium infection and CD4 count, Human Immunodeficiency Virus (HIV) p24 antigenemia or opportunistic infection.

Detection and identification of Mycobacterium avium in the blood of AIDS patients by the polymerase chain reaction

One hundred fifty-three blood samples from patients positive for the human immunodeficiency virus (HIV) were analyzed by polymerase chain reaction (PCR) to detect the presence of Mycobacterium avium. Samples were collected from patients who also had blood cultures performed by a radiometric method. Blood samples were centrifuged on a Ficoll-Hypaque gradient to purify peripheral blood mononuclear cells. The purified cells were washed and incubated with a resin, boiled to release mycobacterial DNA, and then amplified. Polymerase chain reaction products were detected by a nonisotopic method. A 123 base-pair (bp) insertion sequence, namely IS6110, from Mycobacterium tuberculosis complex was also included in the reaction as an internal control of Taq polymerase activity to exclude the presence of enzyme inhibitors. This IS6110 fragment can be distinguished from the 383 bp target product on ethidium bromide-stained agarose gel and may also be used in a colorimetric assay. Such results were compared with the results of culture and indicated that the assay is as sensitive as bacteriological methods, though faster.

Characterization of T cell subsets involved in the production of IFN-gamma in asymptomatic HIV-infected patients

Cells capable of interferon (IFN)-gamma synthesis following mitogenic stimulation can be detected and quantified by a recently developed immunofluorescence assay and flow cytometric analysis. The production of IFN-gamma was investigated in a cohort of 20 asymptomatic human immunodeficiency virus (HIV)-seropositive patients with normal numbers of CD4+ lymphocytes, and in 10 healthy subjects. About 60% of asymptomatic stage A1 patients had increased percentages of blood lymphocytes capable of IFN-gamma synthesis, as compared to healthy subjects. The difference reflected the relatively higher numbers of CD8+ cells, in particular the CD8+ T cell subset lacking CD28 antigen expression. The strong correlation between the CD4+/CD8+ ratio and the CD8+CD28+/CD8+CD28- ratio suggests either a role for CD4+ cells in controlling the CD28+ phenotype or a role for CD8+CD28- cells in the decline of CD4+ lymphocytes. The peculiar ability of CD8+CD28- cells to produce high amounts of IFN-gamma, as compared to CD8+CD28+ cells, supports the hypothesis that the CD8+CD28- lymphocytes constitute a population that is functionally distinct from their double-positive counterparts.

IFN-gamma restores HIV- and non-HIV-specific cell mediated immune response in vitro and its activity is neutralized by antibodies from patients with AIDS

The addition of IFN-gamma to cultures of peripheral blood mononuclear cells (PBMCs) obtained from asymptomatic HIV-infected patients increased cell proliferation in response to HIV envelope synthetic peptides (Env), influenza A virus (VIRUS), and allogeneic lymphocytes (ALLO) but not to phytohaemagglutinin (PHA) stimulation. F(Ab)2 fragments of IgG purified from the sera of HIV-seropositive patients specifically interfered with IFN-gamma-induced cell proliferation in response to recall antigens. Neutralization of the lymphokine activity was found to be sustained by specific IFN-gamma antibodies. Data obtained demonstrate that IFN-gamma can restore the cell-mediated immunity of a number of asymptomatic HIV+ individuals in vitro, while IFN-gamma antibodies present in sera of patients with AIDS interfere with the activity of the lymphokine.

CD4+ and CD8+ lymphocytes of patients with AIDS synthesize increased amounts of interferon-gamma

Individual cells capable of interferon-gamma (IFN-gamma) synthesis are easily detected by immunofluorescence and flow cytometric analysis using an anti-IFN-gamma monoclonal antibody as specific reagent. By IFN-gamma flow cytometry assay, we demonstrated that HIV-seropositive patients, starting at the early stage of viral infection, generally have an increased percentage of lymphocytes potentially able to produce IFN-gamma, compared with healthy blood donors. IFN-gamma expression in patient lymphocytes was observed to increase with the progressive stages of HIV infection, with the highest figures occurring in stage C patients. Such increased IFN-gamma expression involved both CD4+ and CD8+ T cell subsets. Most interestingly, we found patients at the same stage of HIV infection who had similar numbers of total and CD4+ lymphocytes but highly different percentages of lymphocytes potentially capable of producing IFN-gamma.

Effect of galanin on growth hormone (GH) response to thyrotropin releasing hormone of rat pituitary GH-secreting adenomatous cells (GH1) in culture

The growth hormone (GH) releasing effect of thyrotropin-releasing hormone (TRH) and galanin, a 29-amino acid peptide widely distributed in mammalian CNS, alone or in combination was investigated in cultured rat pituitary tumor cells (GH1). TRH stimulated GH secretion in GH1 cells (maximal stimulation at the dose of 0.1 microM). Galanin alone had a significant GH inhibitory effect in GH1 cells at all the doses used. When the two peptides were administered in combination, no significant changes as compared to baseline levels were observed. The results of this study indicate that galanin has potent direct inhibitory effects on baseline and TRH-stimulated GH release from rat tumor cells.

Monoclonal antibodies against antigens exposed on the surface of vegetative forms and spores of Myxococcus virescens

Twelve monoclonal antibodies (mAbs) directed against cell-surface antigens of Myxococcus virescens cells were developed and partially characterized. All of them recognized multiple, diffuse proteic bands in Western blot and four were also reactive to living bacteria, as assessed by flow cytometry. The four latter mAbs recognized antigens common to a number of vegetative forms and spores. The selective expression of proteins recognized by mAbs on the microorganisms and the possible applications of mAbs to the study of myxobacterial cell interaction are discussed.

Purification of LamB proteins using continuous elution electrophoresis: a comparison with immunoaffinity chromatography

LamB is a membrane protein that allows the exposition of a foreign peptide on the surface of a recombinant E. coli cells. An immunopurified hybrid LamB protein has been used to elicit high-titre antibodies to a foreign epitope. Looking for a simpler purification procedure we have compared the traditional approach, which includes affinity chromatography, to continuous elution electrophoresis, in the purification of two different hybrid LamB proteins as foreign epitopes. The results obtained showed that both methods yielded the same purification, although the electrophoretic procedure had a higher yield. Continuous-elution electrophoresis could be a useful tool for the purification of membrane proteins.

A monoclonal antibody to the NH2-terminal region of human interferon-gamma inhibits its antiproliferative activity without affecting its internalization

MAb IGMB-15, an anti-hIFN-gamma MAb, neutralizes the antiproliferative activity of hIFN-gamma without affecting that of hIFN-alpha or hIFN-beta. The neutralizing capacity of MAb IGMB-15 is wide: it has been assessed on cell lines whose origin and sensitivity to hIFN-gamma differ. The binding of hIFN-gamma to its receptor and its subsequent internalization into the target cell were not influenced by the antibody. MAb IGMB-15 has been found to interact with hIFN-gamma in solution but not when the lymphokine was associated with its cell surface receptor, showing that the growth of certain cell lines can be inhibited at the cell membrane level. This finding is consistent with the existence of an accessory factor responsible for the antiproliferative activity of hIFN-gamma.