First year of pre-exposure prophylaxis implementation in France with daily or on-demand tenofovir disoproxil fumarate/emtricitabine.

BACKGROUND: In January 2016, the French Medicine Agency initiated a Temporary Recommendation for Use (TRU) to allow the use of oral intake of tenofovir disoproxil fumarate and emtricitabine for pre-exposure prophylaxis (PrEP) in adults at high risk of HIV. We report the results of the first year of PrEP implementation in France. METHODS: Data were collected by physicians using a secured web subject-monitoring interface, with two forms: an initiation form, with patients' baseline characteristics, and an HIV seroconversion form. Univariate and adjusted multivariate analysis using a logistic regression model were performed to identify baseline factors associated with on-demand PrEP regimen prescription. RESULTS: From 4 January 2016 to 28 February 2017, 3405 subjects were enrolled, with 2774 initiation forms completed; 98.1% were male and 96.9% were MSM. An on-demand regimen was prescribed to 57% of subjects. Older age (OR for participants older than 50 years = 1.76, 95% CI 1.35-2.3, P < 0.001) and site of prescription (OR of former IPERGAY sites = 2.28, 95% CI 1.84-2.83, P < 0.001) were associated with on-demand prescription. Those reporting sexually transmitted infection (STI) and condomless anal sex with at least two different partners were less likely to receive on-demand PrEP (OR = 0.68, 95% CI 0.57-0.82 and 0.75, 95% CI 0.57-0.98, respectively; P < 0.05 for all). Four breakthrough HIV infections were reported during the study, in the context of PrEP interruption or acute infection at the time of PrEP initiation. CONCLUSIONS: In a real-life setting in France, PrEP was used, either daily or on-demand, mostly by MSM, with breakthrough infections being rare.

Oxygen Sensing by Arterial Chemoreceptors Depends on Mitochondrial Complex I Signaling.

O2 sensing is essential for mammalian homeostasis. Peripheral chemoreceptors such as the carotid body (CB) contain cells with O2-sensitive K(+) channels, which are inhibited by hypoxia to trigger fast adaptive cardiorespiratory reflexes. How variations of O2 tension (PO2) are detected and the mechanisms whereby these changes are conveyed to membrane ion channels have remained elusive. We have studied acute O2 sensing in conditional knockout mice lacking mitochondrial complex I (MCI) genes. We inactivated Ndufs2, which encodes a protein that participates in ubiquinone binding. Ndufs2-null mice lose the hyperventilatory response to hypoxia, although they respond to hypercapnia. Ndufs2-deficient CB cells have normal functions and ATP content but are insensitive to changes in PO2. Our data suggest that chemoreceptor cells have a specialized succinate-dependent metabolism that induces an MCI state during hypoxia, characterized by the production of reactive oxygen species and accumulation of reduced pyridine nucleotides, which signal neighboring K(+) channels.

Different dynamin blockers interfere with distinct phases of synaptic endocytosis during stimulation in motoneurones.

KEY POINTS: Neurotransmitter release requires a tight coupling between synaptic vesicle exocytosis and endocytosis with dynamin being a key protein in that process. We used imaging techniques to examine the time course of endocytosis at mouse motor nerve terminals expressing synaptopHluorin, a genetically encoded reporter of the synaptic vesicle cycle. We separated two sequential phases of endocytosis taking place during the stimulation train: early and late endocytosis. Freshly released synaptic vesicle proteins are preferentially retrieved during the early phase, which is very sensitive to dynasore, an inhibitor of dynamin GTPase activity. Synaptic vesicle proteins pre-existing at the plasma membrane before the stimulation are preferentially retrieved during the late phase, which is very sensitive to myristyl trimethyl ammonium bromide (MitMAB), an inhibitor of the dynamin-phospholipid interaction. ABSTRACT: Synaptic endocytosis is essential at nerve terminals to maintain neurotransmitter release by exocytosis. Here, at the neuromuscular junction of synaptopHluorin (spH) transgenic mice, we have used imaging to study exo- and endocytosis occurring simultaneously during nerve stimulation. We observed two endocytosis components, which occur sequentially during stimulation. The early component of endocytosis apparently internalizes spH molecules freshly exocytosed. This component was sensitive to dynasore, a blocker of dynamin 1 GTPase activity. In contrast, this early component was resistant to myristyl trimethyl ammonium bromide (MiTMAB), a competitive agent that blocks dynamin binding to phospholipid membranes. The late component of endocytosis is likely to internalize spH molecules that pre-exist at the plasma membrane before stimulation starts. This component was blocked by MiTMAB, perhaps by impairing the binding of dynamin or other key endocytic proteins to phospholipid membranes. Our study suggests the co-existence of two sequential synaptic endocytosis steps taking place during stimulation that are susceptible to pharmacological dissection: an initial step, preferentially sensitive to dynasore, that internalizes vesicular components immediately after they are released, and a MiTMAB-sensitive step that internalizes vesicular components pre-existing at the plasma membrane surface. In addition, we report that post-stimulus endocytosis also has several components with different sensitivities to dynasore and MiTMAB.

Differential impairment of catecholaminergic cell maturation and survival by genetic mitochondrial complex II dysfunction.

The SDHD gene (subunit D of succinate dehydrogenase) has been shown to be involved in the generation of paragangliomas and pheochromocytomas. Loss of heterozygosity of the normal allele is necessary for tumor transformation of the affected cells. As complete SdhD deletion is lethal, we have generated mouse models carrying a "floxed" SdhD allele and either an inducible (SDHD-ESR strain) or a catecholaminergic tissue-specific (TH-SDHD strain) CRE recombinase. Ablation of both SdhD alleles in adult SDHD-ESR mice did not result in generation of paragangliomas or pheochromocytomas. In contrast, carotid bodies from these animals showed smaller volume than controls. In accord with these observations, the TH-SDHD mice had decreased cell numbers in the adrenal medulla, carotid body, and superior cervical ganglion. They also manifested inhibited postnatal maturation of mesencephalic dopaminergic neurons and progressive cell loss during the first year of life. These alterations were particularly intense in the substantia nigra, the most affected neuronal population in Parkinson's disease. Unexpectedly, TH(+) neurons in the locus coeruleus and group A13, also lacking the SdhD gene, were unaltered. These data indicate that complete loss of SdhD is not sufficient to induce tumorigenesis in mice. They suggest that substantia nigra neurons are more susceptible to mitochondrial damage than other catecholaminergic cells, particularly during a critical postnatal maturation period.

Gene expression profiles in the cerebellum of transgenic mice over expressing the human FMR1 gene with CGG repeats in the normal range.

Modifications in the GABA pathway are considered to be responsible for motor alterations in animal models for fragile X-associated tremor ataxia syndrome. We analyzed the expression profile in the cerebellum in a transgenic mouse model that over expresses the human FMR1 gene with CGG repeats in the normal range. We used the "GeneChip Mouse Gene 1.0 ST Array" from Affymetrix analyzing 28,853 well-described and -characterized genes. Based on data from the comparative analysis of the expression profile, we detected a significant gradient with a P value <0.1 and changes in expression equal to or greater than 1.5 times compared to the control mouse genes. There were significant changes in the expression of 104 genes, among which 72% had decreased and 28% had increased expression. With the exception of GabarapL2, no changes in expression of genes from the GABA pathway were observed, which may explain the absence of an altered motor phenotype in these mice. These results further support the view that toxic effects in fragile X-associated tremor ataxia syndrome are due to expansion of CGG repeats rather than increased mRNA levels, since in the transgenic mice the FMR1 mRNA levels were increased 20-100 times compared with those of control littermates.

Ovarian steroids regulate tachykinin and tachykinin receptor gene expression in the mouse uterus.

BACKGROUND: In the mouse uterus, pregnancy is accompanied by changes in tachykinin and tachykinin receptor gene expression and in the uterotonic effects of endogenous tachykinins. In this study we have investigated whether changes in tachykinin expression and responses are a result of changes in ovarian steroid levels. METHODS: We quantified the mRNAs of tachykinins and tachykinin receptors in uteri from ovariectomized mice and studied their regulation in response to estrogen and progesterone using real-time quantitative RT-PCR. Early (3 h) and late (24 h) responses to estrogen were evaluated and the participation of the estrogen receptors (ER), ERalpha and ERbeta, was analyzed by treating mice with propylpyrazole triol, a selective ERalpha agonist, or diarylpropionitrile, a selective agonist of ERbeta. RESULTS: All genes encoding tachykinins (Tac1, Tac2 and Tac4) and tachykinin receptors (Tacr1, Tacr2 and Tacr3) were expressed in uteri from ovariectomized mice. Estrogen increased Tac1 and Tacr1 mRNA after 3 h and decreased Tac1 and Tac4 expression after 24 h. Tac2 and Tacr3 mRNA levels were decreased by estrogen at both 3 and 24 h. Most effects of estrogen were also observed in animals treated with propylpyrazole triol. Progesterone treatment increased the levels of Tac2. CONCLUSION: These results show that the expression of tachykinins and their receptors in the mouse uterus is tightly and differentially regulated by ovarian steroids. Estrogen effects are mainly mediated by ERalpha supporting an essential role for this estrogen receptor in the regulation of the tachykinergic system in the mouse uterus.

Vasculitis leucocitoclástica como primera manifestación de pleuritis tuberculosa / Leukocytoclastic vasculitis as the first manifestation of tuberculous pleuritis

En nuestro país la tuberculosis es aún una enfermedad muy prevalente. La tuberculosis puede comprometer cualquier órgano, uno de ellos es la piel. Este compromiso dérmico, se puede evidenciar por la formación de inmunocomplejos que se depositan en la piel y se manifiestan como vasculitis leucocitoclástica. Se presenta el caso de un paciente de 34 años, con un tiempo de enfermedad de cuatro meses, cuyas manifestaciones clínicas iniciales fueron púrpura palpable en miembros inferiores y poliartralgias, quien recibió antinflamatorios no esteroideos durante un mes, presentando leve mejoría de dichas lesiones; luego de un periodo subclínico reinicia sintomatología con fiebre, astenia y dolor torácico. Se evidenció derrame pleural izquierdo, el cual dio como resultado un exudado mononuclear y adenosin deaminasa elevada. En la biopsia pleural se observó granulomas y se evidenció BK positivo. En la biopsia de piel se evidenció una vasculitis leucocitoclástica. Recibió tratamiento específico esquema I, con evolución clínica favorable a los diez días.

In our country tuberculosis is still a very prevalent disease. Tuberculosis can affect any organ, included the skin. This cutaneous disorder can be evidenced by the formation of immunocomplex that are deposited at the skin and manifested as leukocytoclastic vasculitis. We describe the case of a 34 years old patient, with an illness time of four months, whose initial clinical manifestations were palpable purpura on the lower limbs and polyarthralgia, received non-steroidalanti inflammatory drugs for a month, showing slight improvement from such injury; after a subclinical period its symptoms restarts with fever, fatigue and pain chest. There was evidence of left pleural effusion, which resulted in an mononuclear exudate and elevationa of adenosine deaminase. Pleural biopsy showed granulomas and positive BK. Skin biopsy showed leukocytoclastic vasculitis. The patient received first line antituberculosis drugs with favorable clinical outcome after ten days.

Absolute requirement of GDNF for adult catecholaminergic neuron survival.

GDNF is a potent neurotrophic factor that protects catecholaminergic neurons from toxic damage and induces fiber outgrowth. However, the actual role of endogenous GDNF in the normal adult brain is unknown, even though GDNF-based therapies are considered promising for neurodegenerative disorders. We have generated a conditional GDNF-null mouse to suppress GDNF expression in adulthood, hence avoiding the developmental compensatory modifications masking its true physiologic action. After Gdnf ablation, mice showed a progressive hypokinesia and a selective decrease of brain tyrosine hydroxylase (Th) mRNA, accompanied by pronounced catecholaminergic cell death, affecting most notably the locus coeruleus, which practically disappears; the substantia nigra; and the ventral tegmental area. These data unequivocally demonstrate that GDNF is indispensable for adult catecholaminergic neuron survival and also show that, under physiologic conditions, downregulation of a single trophic factor can produce massive neuronal death.

A role for tachykinins in the regulation of human sperm motility.

BACKGROUND: Tachykinins and tachykinin receptors are widely distributed in the male reproductive tract and appear to be involved in reproduction. However, the function and expression of tachykinins and their receptors in human spermatozoa remain poorly studied. We analysed the effects of tachykinins on sperm motility and characterized the population of tachykinin receptors in human spermatozoa. METHODS AND RESULTS: Motility analysis was performed following World Health Organization guidelines and we found that substance P (SP), human hemokinin-1 (hHK-1), neurokinin A (NKA) and neurokinin B (NKB) produced concentration-dependent increases in sperm progressive motility. The effects of tachykinins were antagonized by the NK(1) receptor-selective antagonist SR 140333, the NK(2) receptor-selective antagonist, SR 48968 and, to a lesser extent, also by the NK(3) receptor-selective antagonist SR 142801. Immunocytochemistry studies showed expression of the NK(1), NK(2) and NK(3) tachykinin receptor proteins in spermatozoa with different major sites of localization for each receptor. Western blot analysis confirmed the presence of tachykinin receptors in sperm cell homogenates. RT-PCR demonstrated expression of the genes that encode SP/NKA (TAC1), NKB (TAC3) and hHK-1 (TAC4) but not the genes TACR1, TACR2 and TACR3 encoding NK(1), NK(2) and NK(3) receptors, respectively. CONCLUSIONS: These results show for the first time that the NK(1), NK(2) and NK(3) tachykinin receptor proteins are present in human spermatozoa. Our findings suggest that tachykinins, probably acting through these three tachykinin receptors, play a role in the regulation of human sperm motility.

Role of p38 and inducible nitric oxide synthase in the in vivo dopaminergic cells' degeneration induced by inflammatory processes after lipopolysaccharide injection.

Accumulating evidences suggest that neuroinflammation is involved in the progressive death of dopaminergic neurons in Parkinson's disease. Several studies have shown that intranigral injection of lipopolysaccharide induces inflammation in the substantia nigra leading to death of tyrosine hydroxylase-positive cells. To better understand how the inflammatory response gives rise to neurotoxicity we induced inflammation in substantia nigra by injecting lipopolysaccharide. The damage of substantia nigra dopaminergic neurons was evaluated by immunohistochemistry, reverse transcription-PCR and Western blot analysis of tyrosine hydroxylase. In parallel, activation of microglial cells, a hallmark of inflammation in CNS, was revealed by immunohistochemistry. Similarly the expression of molecules involved in the inflammatory response and apoptotic pathway was also tested, such as cytokines (tumor necrosis factor-alpha, interleukin-1beta, interleukin-6), inducible nitric oxide synthase and caspase-11. Tyrosine hydroxylase expression (both mRNA and protein) started to decrease around 3 days post-injection. At the mRNA level, our results showed that the cytokines expression peaked shortly (3-6 h) after lipopolysaccharide injection, followed by the induction of inducible nitric oxide synthase and caspase-11 (14 h). However, inducible nitric oxide synthase protein peaked at 24 h and lasted for 14 days. The lipopolysaccharide-induced loss of substantia nigra dopaminergic neurons was partially inhibited by co-injection of lipopolysaccharide with S-methylisothiourea, an inducible nitric oxide synthase inhibitor. Co-injections of lipopolysaccharide with SB203580, a p38 MAP kinase inhibitor, reduced inducible nitric oxide synthase and caspase-11 mRNA expression, and also rescued dopaminergic neurons in substantia nigra. In summary, this is the first report to describe in vivo the temporal profile of the expression of these inflammatory mediators and proteins involved in dopaminergic neuronal death after intranigral injection of lipopolysaccharide. Moreover data strongly support that lipopolysaccharide-induced dopaminergic cellular death in substantia nigra could be mediated, at least in part, by the p38 signal pathway leading to activation of inducible nitric oxide synthase and caspase-11.

Neuroprotection by transgenic expression of glucose-6-phosphate dehydrogenase in dopaminergic nigrostriatal neurons of mice.

Oxidative damage to dopaminergic nigrostriatal (DNS) neurons plays a central role in the pathogenesis of Parkinson's disease (PD). Glucose-6-phosphate dehydrogenase (G6PD) is a key cytoprotective enzyme that provides NADPH, the major source of the reducing equivalents of a cell. Mutations of this enzyme are the most common enzymopathies worldwide. We have studied in vivo the role of G6PD overexpressed specifically in the DNS pathway and show that the increase of G6PD activity in the soma and axon terminals of DNS neurons, separately from other neurons or glial cells, protects them from parkinsonism. Analysis of DNS neurons by histological, neurochemical, and functional methods showed that even a moderate increase of G6PD activity rendered transgenic mice more resistant than control littermates to the toxic effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The neuroprotective action of G6PD was also observed in aged animals despite that they had a greater susceptibility to MPTP. Therefore, overexpression of G6PD in dopaminergic neurons or pharmacological activation of the native enzyme should be considered as potential therapeutic strategies to PD.

Functional and molecular characterization of tachykinins and tachykinin receptors in the mouse uterus.

The aim of this study was to analyze the function and expression of tachykinins, tachykinin receptors, and neprilysin (NEP) in the mouse uterus. A previous study showed that the uterotonic effects of substance P (SP), neurokinin A (NKA), and neurokinin B (NKB) in estrogen-treated mice were mainly mediated by the tachykinin NK1 receptor. In the present work, further contractility studies were undertaken to determine the nature of the receptors mediating responses to tachykinins in uteri of late pregnant mice. Endpoint and real-time quantitative RT-PCR were used to analyze the expression of the genes that encode the tachykinins SP/NKA, NKB, and hemokinin-1 (HK-1) (Tac1, Tac2, and Tac4); and the genes that encode tachykinin NK1 (Tacr1), NK2 (Tacr2), and NK3 (Tacr3) receptors in uteri from pregnant and nonpregnant mice. The data show that the mRNAs of tachykinins (particularly NKB and HK-1), tachykinin receptors, and NEP are locally expressed in the mouse uterus, and their expression changes during the estrous cycle and during pregnancy. The tachykinin NK1 receptor is the predominant tachykinin receptor in the nonpregnant and early pregnant mouse and may mediate tachykinin-induced uterine contractions in the nonpregnant mouse. The tachykinin NK2 receptor is predominant in the late pregnant mouse and is the main receptor mediating uterotonic responses to tachykinins at late pregnancy. The tachykinin NK3 receptor is expressed in considerable amounts only in uteri from nonpregnant diestrous animals, and its physiological significance remains to be clarified.

The mitochondrial SDHD gene is required for early embryogenesis, and its partial deficiency results in persistent carotid body glomus cell activation with full responsiveness to hypoxia.

The SDHD gene encodes one of the two membrane-anchoring proteins of the succinate dehydrogenase (complex II) of the mitochondrial electron transport chain. This gene has recently been proposed to be involved in oxygen sensing because mutations that cause loss of its function produce hereditary familiar paraganglioma, a tumor of the carotid body (CB), the main arterial chemoreceptor that senses oxygen levels in the blood. Here, we report the generation of a SDHD knockout mouse, which to our knowledge is the first mammalian model lacking a protein of the electron transport chain. Homozygous SDHD(-/-) animals die at early embryonic stages. Heterozygous SDHD(+/-) mice show a general, noncompensated deficiency of succinate dehydrogenase activity without alterations in body weight or major physiological dysfunction. The responsiveness to hypoxia of CBs from SDHD(+/-) mice remains intact, although the loss of an SDHD allele results in abnormal enhancement of resting CB activity due to a decrease of K(+) conductance and persistent Ca(2+) influx into glomus cells. This CB overactivity is linked to a subtle glomus cell hypertrophy and hyperplasia. These observations indicate that constitutive activation of SDHD(+/-) glomus cells precedes CB tumor transformation. They also suggest that, contrary to previous beliefs, mitochondrial complex II is not directly involved in CB oxygen sensing.

A role for tachykinins in female mouse and rat reproductive function.

Tachykinins may be involved in reproduction. A reverse transcription-polymerase chain reaction assay was used to analyze the expression of tachykinins and tachykinin receptors in different types of reproductive cells from mice. The preprotachykinin (PPT) genes, PPT-A, PPT-B and PPT-C, that encode substance P/neurokinin A, neurokinin B, and hemokinin-1, respectively, and the genes that encode the tachykinin NK1, NK2, and NK3 receptors were all expressed, at different levels, in the uterus of superovulated, unfertilized mice. The mRNA of neprilysin (NEP), the main enzyme involved in tachykinin metabolism, was also expressed in the uterus. Isolated cumulus granulosa cells expressed PPT-A, PPT-B, PPT-C, and NEP and low levels of the tachykinin NK1 and NK2 receptors. Mouse oocytes expressed PPT-A and -B mRNA transcripts. A low expression of the three tachykinin receptors was observed but PPT-C and NEP were undetectable. Two- and 8- to 16-cell mouse embryos expressed only a low-abundance transcript corresponding to the NK1 receptor. However, the mRNAs of PPT-B, PPT-C and NEP appeared in blastocyst-stage embryos. A low-abundance transcript corresponding to the NK2 receptor was the only target gene detected in mice sperm. Female mice or rats treated neonatally with capsaicin showed a reduced fertility. A reduction in litter size was observed in female rats treated in vivo with the tachykinin NK3 receptor antagonist SR 142801. These data show that tachykinins of both neuronal and nonneuronal origin are differentially expressed in various types of reproductive cells and may play a role in female reproductive function.

A new epitope on sheep CD45R molecule detected by a monoclonal antibody.

This paper describes the production and characterization of a monoclonal antibody (mAb), Co-46D5, which recognizes a new epitope on the isoform of the homologous sheep leukocyte common antigen (LCA) or CD45. This nmAb was submitted to the 3rd workshop on ruminant leukocyte antigens and was assigned to a cluster reactive with B- and T-cells subsets. Co-46D recognizes a 220 kDa molecule on peripheral blood mononuclear cells (PBMC) and spleen cells but not on thymocytes. Flow cytometry (FCM) analysis shows that Co-46D5 reacted with 30% of PBMC and 50% of spleen cells and more than 95% of cells freshly isolated from lymphoid follicles of the ileal Peyer's patches (IPP) of young lambs. By immunohistochemistry, the antigen was detected mainly on B-cell areas of lymph nodes and spleen. It was also found on a subpopulation of medullar thymocytes. Based on these results, we assume that Co-46D5 recognizes a new epitope on the largest isoform of the sheep CD45 receptor, probably on the homologous to the human CD45RA isoform.

Effect of PGE1 on TNF-alpha status and hepatic D-galactosamine-induced apoptosis in rats.

Prostaglandin E1 has hepatoprotective properties in several clinical and experimental models of liver dysfunction. Hepatotoxicity induced by D-galactosamine (D-GalN) is a suitable animal model of human acute hepatic failure. The aim of the study was to investigate if prostaglandin E1 (PGE1) protection against hepatic D-GalN-induced apoptosis was related to tumour necrosis factor-alpha (TNF-alpha) content in serum. This cytokine is associated with in vitro apoptosis and general inflammatory disorders. In this study, PGE1 was administered 30 min before D-GalN to rats. In other experiments, several doses of TNF-alpha were administered 15min after PGE1 to D-Ga1N-treated rats. Several parameters related to apoptosis and necrosis were measured by flow cytometry, gel electrophoresis, biochemical analysis, and optical and electron microscopy. Tumour necrosis factor-alpha was quantified by competitive enzyme-linked immunosorbent assay (ELISA). PGE1 by itself did not modify the cell cycle of hepatocytes and liver toxicity, but increased TNF-alpha in serum in comparison with the control group. D-Galactosamine increased the percentage of hepatocytes in apoptosis and in the S phase of the cell cycle, and decreased those in G0/G1. Such an increase of hepatocytes in apoptosis was correlated with a higher number of apoptotic bodies and DNA fragmentation in liver than control samples. Also, D-GalN increased alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase and TNF-alpha in serum compared with the control group. Pre-administration of PGE1 to D-GalN-treated rats reduced all the parameters of apoptosis and necrosis in liver, and increased additionallyTNF-alpha content in serum. In those experiments where low doses of TNF-alpha were administered to PGE1 and D-GalN-treated rats an inverse relationship appeared between TNF-alpha and ALT content in serum. In conclusion, the protective effects of PGE1 on D-GalN-induced apoptosis may be linked to its capacity to modulate cell division and/or its immunomodulatory activity. In this sense, our experimental results suggest that TNF-alpha could be involved in protection or exacerbation of liver damage in relation to the pathophysiological status of the liver.

Ruminant cluster WC13.

Five monoclonal antibodies (mAbs) belonged to preliminary cluster 27; however, only two mAbs, Buf13 (3W-506) and Co-3D1D4 (3W-202), were shown to detect the same surface antigen and belong to WC13. The other three mAbs, IVA120 (3W-323), IVA197 (3W-533) and IVA198 (3W-290), detected a 45 kDa molecule that could be fibrinogen (Mateo A., Perez de la Lastra, J., Moreno, A., Dusinsky, R., Bilka, F., Simon, M., Horovska, L., Naessens, J. and Llanes, D., 1996. Biochemical characterization of antigens detected with anti-platelet monoclonal antibodies. Vet. Immunol. Immunopathol., 52: 363-370; Perez de la Lastra, J.M., Mateo, Dusinsky, R., Bilka, Simon, M., Horovska, L. and Llanes, D., 1996. Two monoclonal antibodies from the platelet panel recognize sheep plasma fibronigen. Vet. Immunol. Immunopathol., 52:).

1 alpha, 25-dihydroxyvitamin D3 (calcitriol) induces apoptosis in stimulated T cells through an IL-2 dependent mechanism.

The steroid hormone 1 alpha,25-dihydroxyvitamin D3 (calcitriol) has been shown to inhibit PHA-induced T-cell proliferation. In the present work we show that calcitriol caused a concentration-dependent decrease in the viability of PHA stimulated but not unstimulated T lymphocytes. Under microscopy, nonviable cells exhibit classic features of programmed cell death or apoptosis. In addition, the same concentration of calcitriol induces a blockage in the G1 phase of T cell cycle and decreased secretion of IL-2, which was correlated with the extent of apoptosis. Thus, addition of exogenous IL-2 reverted both the cell cycle block and the apoptotic cell death induced by calcitriol. This data indicates that calcitriol induced apoptosis in PHA-stimulated T cell, and suggests that this action is mediated through suppression of IL-2 secretion.