Immunologic parameters in systemic sclerosis

BACKGROUND

Immunologic abnormalities seem to play an important role in important role in systemic sclerosis (SSc).

METHODS

We studied the following immune parameters to get more insight into SSc: autoantibodies (antinuclear antibodies (ANA), anti-Scl-70, anticentromere antibodies (ACA) subsets of lymphocyte subpopulations and markers of their activation, as well as serum levels of IL-2, the soluble IL-2 receptor (SIL-2R), IL-6 and its correlation to N-terminal procollagen-III propeptide (P III P), and finally, the IL-6 production by SSc and normal dermal fibroblasts.

RESULTS

In patients with active SSc, we found a reduced number of CD2+ T-lymphocytes and an increase in the expression of T-lymphocyte activation markers such as CD25+ and CD71+, HLA-DR Ia, as well as elevated serum levels of SIL-2LR and IL-6. SSc fibroblasts did not produce more IL-6 than normal fibroblasts in monolayer cultures.

CONCLUSIONS

Our data show that a wide range of immunologic parameters are altered in SSc. In general, T-helper (TH) lymphocytes are activated possibly because of reduced T-suppressor (TS) and natural killer (NK)-cell levels. TH may polyclonally stimulate B cells, which in turn produce higher amounts of autoantibodies. Our findings support the concept that TH cell-derived cytokines/growth factors stimulate matrix protein synthesis by fibroblasts, resulting in generalized fibrosis.

Mode of replication of lymphocytic choriomeningitis virus in persistently infected cultivated mouse L cells

During persistent infection of mouse L cells with strain Armstrong lymphocytic choriomeningitis virus, the latter undergoes characteristic changes, including loss of mouse pathogenicity and failure to form plaques on cultivated cells. We call this virus L(Arm) and have analyzed transcription and translation of its S-RNA, which codes for the viral nucleoprotein (NP) and the glycoprotein precursor (GP-C). In L(Arm) virus-infected L cells, S-RNA and genomic-sized viral complementary S-RNA (VC-S-RNA) were detected and, in addition, considerable quantities of shortened molecules of either species. The cells' content of NP was high, but they contained little GP-C; instead, a viral glycoprotein with MW 65,000 was present. We propose a hypothesis in which it is assumed that along the VC-S-RNA there is more than one recognition site for the viral RNA-dependent RNA polymerase, which leads to the generation of truncated forms of S-RNA, VC-S-RNA, and mRNA for GP-C; this, in turn, results in relative overproduction of NP and relative underproduction of GP-C as well as the emergence of a new form of viral glycoprotein.

Virus-specific delayed-type hypersensitivity (DTH). Cells mediating lymphocytic choriomeningitis virus-specific DTH reaction in mice

We had previously shown that the local lymphocytic choriomeningitis virus-induced delayed-type hypersensitivity (DTH) reaction in mice consists of two well delineated phases that are mediated by CD8+ and CD4+ T lymphocytes, respectively. These findings have been confirmed and extended by showing that the first CD8+ cell-dependent part of the response was enhanced by either the presence of CD4+ cells or systemic treatment with IL-2 and that it developed in the absence of detectable numbers of mononuclear phagocytes, whereas the later CD4+ cell part required monocytes or related elements. Furthermore, in the DTH reaction that was elicited with noninfectious viral Ag in mice previously immunized by infection, only the CD4+ cells participated. Thus, the two phases of the lymphocytic choriomeningitis-viral DTH reaction are principally different, which has to be taken into account when trying to assess the relevance of DTH during this virus infection.

Virus-specific delayed-type hypersensitivity (DTH). Cells mediating lymphocytic choriomeningitis virus-specific DTH reaction in mice

We had previously shown that the local lymphocytic choriomeningitis virus-induced delayed-type hypersensitivity (DTH) reaction in mice consists of two well delineated phases that are mediated by CD8+ and CD4+ T lymphocytes, respectively. These findings have been confirmed and extended by showing that the first CD8+ cell-dependent part of the response was enhanced by either the presence of CD4+ cells or systemic treatment with IL-2 and that it developed in the absence of detectable numbers of mononuclear phagocytes, whereas the later CD4+ cell part required monocytes or related elements. Furthermore, in the DTH reaction that was elicited with noninfectious viral Ag in mice previously immunized by infection, only the CD4+ cells participated. Thus, the two phases of the lymphocytic choriomeningitis-viral DTH reaction are principally different, which has to be taken into account when trying to assess the relevance of DTH during this virus infection.

Effect of rimantadine on cytotoxic T lymphocyte responses and immunity to reinfection in mice infected with influenza A virus

Administration of rimantadine to mice via drinking water, following a prophylactic dose, reduced lung virus titers by greater than 3 log10 plague-forming units (pfu)/ml but caused only marginal reductions in lung virus titers when therapy was started 8 h after exposure to virus. Mice given rimantadine prophylactically plus therapeutically were resistant to rechallenge with virus at a dose equivalent to that used for the primary infection (50 pfu/mouse) but not to a high dose (1 x 10(5) pfu/mouse). Virus-neutralizing-antibody titers were reduced only by rimantadine treatment, which included prophylaxis, whereas the cytotoxic T lymphocyte (CTL) response was depressed by treatment given with or without prophylaxis. Mice infected with rimantadine-resistant virus had no decrease in CTL or antibody responses when treated with rimantadine. Therefore, the depression in CTL and antibody responses associated with rimantadine treatment appears to be due to a decrease in the amount of viral antigen available or interference with viral antigen processing and not to nonspecific immunosuppressive effects.

Efficacy of rimantadine hydrochloride in the treatment of influenza infection of mice

Rimantadine HCl was assessed for its effect on influenza A virus titer in lungs of infected BALB/c mice. Rimantadine administered orally via drinking water, with and without an intraperitoneal prophylactic loading dose, was compared to intraperitoneal administration. Mice were infected with a non-lethal dose of influenza A/Port Chalmers/H3N2 virus and the pulmonary virus titers were determined at intervals over a 21 day period. Prophylactic treatment with rimantadine followed by oral administration resulted in up to a 4 log10 reduction in pulmonary virus titer. The oral doses given to the mice were comparable on a mg/kg/day basis to those recommended for treatment of human infections. Reductions in pulmonary virus titers also occurred after intraperitoneal rimantadine treatment which included a prophylactic dose, but the reductions in pulmonary virus titers were less striking and not consistent over the course of infection. There were no significant reductions in pulmonary virus titers by either route if treatment was started 8 h after exposure to virus.

Extraction and rapid inactivation of proteins from Saccharomyces cerevisiae by trichloroacetic acid precipitation

Methods currently used for the extraction of proteins from yeast involve relatively long time periods between sampling cells from a culture and analysis of their proteins by polyacrylamide gel electrophoresis-sodium dodecylsulphate. Often it is desirable to inactivate cellular metabolism rapidly after sampling and here we show that trichloroacetic acid precipitation techniques, often used for rapid extraction and inactivation of proteins from higher eukaryotes, can be adapted for use with organisms which have cell walls.

Hepatic dopamine sulfotransferases in untreated rats and in rats subjected to endocrine or hypertension-related treatments

Here we describe the dopamine sulfotransferase activity of rat liver cytosol. With cytosol, 3'-phosphoadenosine-5'-phosphosulfate and dopamine Km values were 17.2 +/- 4.1 and 22.4 +/- 3.5 microM. Females possessed 23 to 37% of dopamine sulfotransferase levels, per gm liver, in males. DEAE-Sephadex A-50 chromatography resolved dopamine sulfotransferase activity to dopamine sulfotransferase I and dopamine sulfotransferase II. Dopamine sulfotransferase II comprised 79 +/- 10 or 61 +/- 18% of dopamine sulfotransferase in males or females in routine assays. 4-Methoxytyramine gave 609 or 179% of mean dopamine sulfotransferase activity with dopamine sulfotransferase I or II. Dopamine and 3-methoxytyramine were comparable substrates. Epinephrine was less effective. Mn++, Cd++, Zn++, Na+ and K+ inhibited dopamine sulfotransferase II. Mg++ activated it. Dopamine sulfotransferase II from males was purified 184 +/- 64-fold. Its Km values for 3'-phosphoadenosine-5'-phosphosulfate and dopamine were 12.7 +/- 1.5 and 47.5 +/- 6.7 microM, respectively. Its dopamine sulfotransferase mechanism was sequential. The molecular weight of dopamine sulfotransferase II was 49,100 +/- 4,000 by Sephadex G-100 chromatography. Dopamine sulfotransferase II preferred phenol to catecholamines. Dopamine and 3,4-dihydroxybenzylamine were its best catecholamine substrates. Adrenalectomy or castration of males led to 35 or 45% mean decreases of dopamine sulfotransferase levels, indicating adrenal and gonadal participation in control of dopamine sulfotransferase production. Testosterone had no effect in either sex, whereas estradiol led to 40% mean decreases of dopamine sulfotransferase levels in males. This suggested a role for ovaries in dopamine sulfotransferase production, supported by 55 to 102% increased dopamine sulfotransferase levels after ovariectomy. Okamoto-hypertensive males or males given hypertensogenic doses of cortisol exhibited 37 or 48% mean increases of dopamine sulfotransferase levels per gm liver. Antihypertensive spironolactone or hydralazine led to 30% mean decreases of dopamine sulfotransferase levels. Altered dopamine sulfotransferase levels after all experimental manipulations were due mostly to changed dopamine sulfotransferase II content. Dopamine sulfotransferase II is compared to other reported enzymes that sulfate catecholamines.

Host cell-dependent homologous interference in lymphocytic choriomeningitis virus infection

The generation of virus progeny as well as transcription, translation, and replication of the viral small RNA (S-RNA), which codes for the nucleoprotein (NP) and the glycoprotein precursor (GPC), was followed in L and MDCK cells after infection with multiplicities (m.o.i.) ranging from 0.01 to 100. In L cells, the yields of both plaque-forming units and interfering particles varied inversely with the m.o.i. Northern blot analysis revealed that early after infection with high multiplicity NP-mRNA was present, but later few or no signals of any specificity were registered. After low m.o.i. the results were negative at 8 hr, but large quantities of mRNAs for NP and GPC as well as viral genomic S-RNA and genomic-sized complementary S-RNA had been synthesized at 48 hr. In MDCK cells, throughout the range of m.o.i. both entities attained lower levels and most were generated at m.o.i. one. The degree of hybridization correlated roughly with the quantity of infectious virus to which the cells had been exposed. In the cells of both lines the NP-mRNA corresponded to the synthesis of its translation product, but once produced, most of it appeared to be retained in the phosphorylated form. We assume that the homologous interference seen in L cells after infection with high m.o.i. results from a host-dependent inhibition of viral transcription and replication mediated by NP.

Lymphocytic choriomeningitis virus. X. Demonstration of nucleoprotein on the surface of infected cells

Of a total of 17 monoclonal antibodies (MAb) directed against structural proteins of the lymphocytic choriomeningitis (LCM) virus, 3 were specific for the viral nucleoprotein (p63) and attached to the plasma membrane of infected cells, as disclosed by the indirect immunofluorescence procedure and complement-mediated cytolysis. We had previously demonstrated that a portion of the nucleoprotein (p63E) was part of the envelope of the intact virion (M. Bruns, W. Zeller, H. Rohdewohld, and F. Lehmann-Grube (1986) Virology 151, 77-85), and we now show that after external iodination of virions followed by limited proteolysis the label was attached to the smallest peptide thus obtained. If purified nucleocapsids were labeled with 125I, digested as before, and incubated with an anti-p63 MAb that has the ability to bind the surface of the infected cell, a similarly small peptide was precipitated; an antibody specific for p63 but not recognizing it on the cell surface precipitated the largest peptide and failed to bring down the small one. We conclude that the epitopes complementary to a few of our anti-p63 MAb are represented on both the virion and the surface of virus-infected cells.

Lymphocytic choriomeningitis virus. IX. Properties of the nucleocapsid

Nucleocapsids (NC) of lymphocytic choriomeningitis (LCM) virus were obtained by treatment of purified infectious virus with detergent and salt at high concentrations, followed by gradient centrifugation. NC thus prepared contained 31 S RNA, 23 S RNA, and a protein with an apparent mol wt 63,000 and an isoelectric point pH 5.7 (p63), assumed to be the nucleoprotein. We had previously observed that the intact LCM virus contained two kinds of protein with mol wt 63,000 separable by their isoelectric points which were pH 5.7 and 7.7, respectively. We now found that the latter component was removed from the NC together with the glycoproteins, and labeling studies revealed that it was closely associated with the viral envelope. We have named the protein with a mol wt of 63,000 and an isoelectric point pH 7.7 p63E (E for envelope). By limited proteolysis both viral components of mol wt 63,000 could not be distinguished, indicating that they are basically identical. It appears that p63E is the phosphorylated form of p63.

Lymphocytic choriomeningitis virus. VII. Structural alterations of the virion by treatment with proteolytic enzymes without loss of infectivity

Treatment of lymphocytic choriomeningitis virus with proteolytic enzymes, hyaluronidase, and phospholipase C increased infectious titres. Biochemical analysis of bromelain- and trypsin-treated virus revealed that infectivity was high in spite of the decrease to low or undetectable levels of all viral glycoproteins as well as partial degradation of the nucleoprotein.

Lymphocytic choriomeningitis virus. VIII. Reciprocal formation of pseudotypes with vesicular stomatitis virus

Large numbers of VSV (LCMV) pseudotypes with the genomes of vesicular stomatitis virus (VSV) and the coat proteins of lymphocytic choriomeningitis virus (LCMV) were produced by infecting L cells first with LCMV and subsequently with VSV, the latter in the presence of tunicamycin. Separation by gradient centrifugation from the concomitantly produced LCMV genotypes, followed by polyacrylamide gel electrophoresis (PAGE), failed to reveal measurable quantities of the one glycoprotein ("G") of VSV. By serologic analysis it could be shown that anti-VSV antibody still attached, although with low efficiency. VSV (LCMV) retained its infectivity during purification. Reversal of the sequence of infection under otherwise identical conditions led to the formation of LCMV (VSV) pseudotypes. When separated from VSV genotypes, PAGE did not disclose glycoproteins of LCMV, and serologic analysis failed to detect attachment of anti-LCM virus antibody. LCMV (VSV) lost its infectivity during purification.

Lymphocytic choriomeningitis virus. IV. Electron microscopic investigation of the virion

The structure of lymphocytic choriomeningitis virus (LCM virus) was investigated by a variety of conventional as well as novel electron microscopic procedures. Thin sections of infected cells revealed the characteristic arenavirus entities whose interiors contain ribosome-like granules but look otherwise empty. In contrast, most thin-sectioned virus particles from infectious cell culture fluid, both untreated and highly purified with little loss of initial infectivity, appeared to be filled with rather homogeneous cores. Cores rather than granules were also found in positively contrasted whole and thin-sectioned virus particles. We favor the explanation that the sandy grains, which have given this group of viruses its name, are altered cores that happen to look like ribosomes. However, the alternative cannot yet be excluded, namely, that LCM virus-infected cells produce two types of particles, of which only the core-containing ones represent virions.

Lymphocytic choriomeningitis virus. VI. Isolation of a glycoprotein mediating neutralization

A structural glycoprotein of lymphocytic choriomeningitis virus was obtained in pure form by immunoaffinity chromatography using a monoclonal antibody with high neutralizing activity. It blocked neutralization of viral infectivity by antibody and in polyacrylamide gel electrophoresis it migrated with an apparent molecular weight of 44 X 10(3). We conclude that the isolated material is identical with the previously described gp44 (GP-1).

Lymphocytic choriomeningitis virus. V. Proposed structural arrangement of proteins in the virion

Previous work by M.J. Buchmeier and his colleagues and by our group has led to the conclusion that the lymphocytic choriomeningitis (LCM) virus contains seven distinct structural proteins, which we have named p200, gp85, p77, p63, gp60, gp44, and gp35. Their arrangement in the virion has now been analysed by establishing nearest-neighbour relationships with a homobifunctional crosslinker, by performing polyacrylamide gel electrophoresis in parallel under reducing and non-reducing conditions, and by determining the proteins that are covalently bound to viral lipids. A hypothetical model of the virion of LCM virus is proposed. Its envelope is assumed to consist of a membranous layer composed of gp60 and lipids and two types of spikes with either gp85 or gp44 as tips and gp35 as bases. The last-mentioned glycoprotein also appears to be complexed with p63, the main protein component of the nucleocapsid, and this in turn was found to be spatially associated with p200. Probably p77 is also an internal component, but a more exact position cannot yet be assigned to this protein.

The influence of the extracellular concentration of calcium, magnesium and sodium on the repolarizing phase of the receptor potential of the Limulus ventral nerve photoreceptor

Lowering the extracellular calcium concentration from 10 mmol/l to 1 nmol/l causes, besides reducing membrane potential (PMP) and peak amplitude (hmax) of the light response of the Limulus ventral nerve photoreceptor (see Stieve and Bruns [1]), a prolongation of the time course of the light response. The retarded time course (characterized by latent-period tlat, time-to-peak tmax, decrease time t2 and decline quotient QHN) caused by low calcium concentration is not antagonized by either reducing the sodium concentration (from 0.5 to 0.05 mol/l) or increasing the magnesium concentration (from 5 X 10(-5) to 5 X 10(-2) mol/l) in contrast to the effects on the PMP and hmax. This effect of lowering the calcium concentration on the time course of the ReP is distinctly different from that on membrane potential and transient of the ReP described before. It is not characterized by a calcium/sodium binding competition but is probably more closely related to the bump-generating mechanism. It can be explained on the assumption that the time parameters of the ReP are primarily determined by the latency distribution of the underlying bumps which is expanded under low calcium conditions.

Lymphocytic choriomeningitis virus. III. Structural proteins of the virion

Analysis of radioactively labelled and highly purified infectious lymphocytic choriomeningitis (LCM) virus by polyacrylamide gel electrophoresis (PAGE) revealed 12 components which, according to their apparent molecular weight and glycosylation status, were designated as p19, p25, p26, gp35, p38, gp44, gp60, p63, p77, gp85, gp130, and p200. As shown by immunoprecipitation, they all bound to rabbit anti-LCM virus antibodies. Three proteins, namely gp35 (= 'GP-2'), gp44 (= 'GP-1') and p63 (= 'NP'), had previously been described by others as major constituents of the virion. Our results confirm this and suggest that gp60, p77, gp85, and p200 are further distinct structural proteins. In contrast, p25 and p38 appear to be cleavage or degradation products of p63; p19 and p26 seem to belong to gp60, which could be the monomeric form of a dimer, gp130. Peptide mapping by limited proteolysis revealed considerable overlapping of amino acid sequences among the major glycoproteins with one peptide being common to all. From the results of PAGE performed after external labelling of intact virions, we conclude that gp44, gp60, and gp85 (but not gp35) form the surface of the virus envelope. Analytical isoelectric focusing under non-reducing conditions has shown that the major glycoproteins appeared to consist of several components with different isoelectric points.

Biochemical composition of lymphocytic choriomeningitis virus interfering particles

Lymphocytic choriomeningitis (LCM) was interfering particles were enriched relative to infectious virions by ultracentrifugation in a shallow gradient made of Urografin. Electrophoretic analysis revealed that they lacked the small ('S') 23S RNA as well as GP-1 and GP-2 of the infectious virion and also lacked a newly characterized glycoprotein of apparent mol. wt. 85 x 10(3); instead, they contained a novel glycoprotein with mol. wt. 65 x 10(3).

Ultrastructural studies on Maedi-Visna virus

Ultrastructural studies of Maedi-Visna virus (MVV) particles isolated from tissue culture fluids of MVV-infected cells as well as cultured cells infected with MVV were performed. MVV particles aree bounded by an envelope with projections loosely attached to its surface. Virions contain a core (sometimes two or more) of conical or ovoid shape enclosing an electron-dense nucleoid which is much smaller in diameter than the core and which can only be seen in ultrathin sections. A distinct core shell is to be found in most of the ultrasectioned particles. Cores, liberated from the virions by detergent treatment, exhibited the same shape as their enveloped counterparts. Budding structures with crescents underlying the cell membrane without an intermediate space seem to be bordered on their cell side by an electron-dense thin layer. Particles obviously representing intervenig stages of viral maturation showing parts of the crescents at the viral membrane and empty core shells could be found in single cases.

Extracellular calcium, magnesium, and sodium ion competition in the conductance control of the photosensory membrane of Limulus ventral nerve photoreceptor

The membrane potential in the dark and the saturated response height of the ventral nerve photoreceptor of Limulus was measured by an intracellular electrode while the external concentration of calcium, magnesium and sodium ions was varied.

Decreasing the extracellular calcium concentration from 10-2 mol/l causes a calcium-dependent lowering of the dark membrane potential and at very low concentrations (<10-8 mol/l a reversal to ca. +5 to +11 mV, if the external magnesium concentration is also low. Also, the light response diminishes with decreasing extracellular calcium concentration and disappears at a concentration of 10-9 mol/l.

External magnesium can substitute for certain properties of extracellular calcium.

Lowering the extracellular sodium concentration from 543 mmol/l to 30 - 50 mmol/1 reduces the dark membrane potential and the light responses at normal calcium concentration, whereas at low calcium concentration it causes a substantial rise of both.

Interpretation: The results are in accordance with our working hypothesis that a strong reduction of the external calcium (and magnesium) concentration causes a calcium concentration dependent opening of “ light channels” in the dark. Additional lowering the extracellular sodium concentration counteracts this effect; opening and closing of light channels is controlled by negative binding sites on the cell membrane for which calcium and sodium ions compete with an antagonistic action.

Comparison of the ribonucleoproteins of different rabies virus serotypes by radioimmunoassay

Radioimmunoassay (RIA) provides a sensitive serological procedure for detecting rabies virus ribonucleoprotein (RNP) as well as its specific antibodies, RIA was carried out using highly purified RNPs labelled by the chloramine-T method. This paper describes optimal conditions for iodination of RNP with high specific activity. The optimal concentrations of 125I, RNP, chloramine-T, and reducing agent as well as the effect of pH on the reaction were investigated. RIA proved to be extremely sensitive for detection of homologous antibodies. In competition experiments the part-relationship of the group-specific RNPs of the three rabies virus serotypes (HEP, MOK and LBV) was confirmed.

Prolonged retention of methyl mercury by mallard drakes

Mallard drakes accumulated mercury rapidly from dietary dosage of methylmercury dicyandiamide and eliminated it slowly, retaining approximately one half at the end of 84 days; no measurable loss occurred between the end of the 7th and 56th days, but loss resumed concurrently with new feather growth, and continued through the 112th day, the close of the study.

Ability to light-induced conductance change of arthropod visual cell membrane, indirectly depending on membrane potential, during depolarization by external potassium or ouabain

Light responses (ReP) and pre-stimulus membrane potential (PMP) and conductance of photoreceptors of Astacus leptodactylus and Limulus polyphemus (lateral eye) were recorded and changes were observed when the photoreceptor was depolarized by the action of external ouabain of high potassium concentration application. 1 mM/1 ouabain application causes a transient increase of PMP and ReP in Limulus, followed by a decrease which is faster for the ReP (half time time 34 min) than for the PMP (half time 80 min). Irreversible loss of excitability occurs when the PMP is still ca. 40% of the reference value. In both preparations high external potassium concentration leads to total depolarization (beyond zero line to + 10-+ 20 mV) of the PMP and after a time lag of 10 min also to a loss of excitability (intracellular recording). In extracellular recordings (Astacus) the excitability remains at a low level of 15%. The effects are reversible and are similar whether no or 10% external sodium is present. In all experiments the light-induced changes of membrane conductance are about parallel to those of the light response. The fact that the ability of the photosensoric membrane to undergo light-induced conductance changes is membrane potential-dependent is discussed, leading to the explanation that dipolar membrane constituents such as channel forming molecules (probably not rhodopsin) have to be ordered by membrane potential to keep the membrane functional for the photosensoric action.