Spontaneous development of protective anti-T cell receptor autoimmunity targeted against a natural EAE-regulatory idiotope located within the 39-59 region of the TCR-V beta 8.2 chain

The development of experimental autoimmune encephalomyelitis (EAE) in Lewis rats is mediated by V beta 8.2+ T cells specific for myelin basic protein. One consequence of this biased expression of V beta 8.2 is the spontaneous development of regulatory T cells and antibodies against residues 39-59 of the V beta 8.2 sequence. Moreover, a synthetic V beta 8.2-39-59 peptide could induce protection against and speed recovery from EAE. T cells and antibodies specific for V beta 8.2-39-59 could transfer protection from EAE. Recently, we reported that the protective T cell epitope is subsumed within the V beta 8-44-54 sequence. We now report that protection induced by V beta 8-44-54 lasted at least 102 days and produced "split tolerance," enhancing anti-myelin basic protein antibody titers but reducing anti-myelin basic protein T cell frequency. The shorter V beta 8-44-54 peptide induced a distinct set of antibodies that did not cross-react with the longer V beta 8.2-39-59 peptide, although both specificities could stain V beta 8.2+ T cells and were equally protective against EAE. However, the V beta 8.2-39-59 peptide, but not the V beta 8-44-54 peptide, would appear to represent the natural idiotope: antibodies to V beta 8.2-39-59 that develop spontaneously during EAE could be boosted to higher titers only by the V beta 8.2-39-59, but not by other TCR peptides from the V beta 8.2 sequence, including V beta 8-44-54 that contains the functional T cell epitope. These results suggest that natural processing of the TCR V beta-chain favors the formation of a peptide that resembles the V beta 8.2-39-59 sequence. The B cell epitope present on the V beta 8-44-54 sequence was evident only in the absence of residues 39-43 and 55-59, suggesting that the two peptides possess distinct conformations. However, the V beta 8-44-54 B cell epitope is most likely expressed on the V beta 8.2+ T cells, either as a low affinity determinant on the intact TCR alpha/beta heterodimer or as a cryptic epitope bound in the cleft of surface MHC molecules.

Spontaneous development of protective anti-T cell receptor autoimmunity targeted against a natural EAE-regulatory idiotope located within the 39-59 region of the TCR-V beta 8.2 chain

The development of experimental autoimmune encephalomyelitis (EAE) in Lewis rats is mediated by V beta 8.2+ T cells specific for myelin basic protein. One consequence of this biased expression of V beta 8.2 is the spontaneous development of regulatory T cells and antibodies against residues 39-59 of the V beta 8.2 sequence. Moreover, a synthetic V beta 8.2-39-59 peptide could induce protection against and speed recovery from EAE. T cells and antibodies specific for V beta 8.2-39-59 could transfer protection from EAE. Recently, we reported that the protective T cell epitope is subsumed within the V beta 8-44-54 sequence. We now report that protection induced by V beta 8-44-54 lasted at least 102 days and produced "split tolerance," enhancing anti-myelin basic protein antibody titers but reducing anti-myelin basic protein T cell frequency. The shorter V beta 8-44-54 peptide induced a distinct set of antibodies that did not cross-react with the longer V beta 8.2-39-59 peptide, although both specificities could stain V beta 8.2+ T cells and were equally protective against EAE. However, the V beta 8.2-39-59 peptide, but not the V beta 8-44-54 peptide, would appear to represent the natural idiotope: antibodies to V beta 8.2-39-59 that develop spontaneously during EAE could be boosted to higher titers only by the V beta 8.2-39-59, but not by other TCR peptides from the V beta 8.2 sequence, including V beta 8-44-54 that contains the functional T cell epitope. These results suggest that natural processing of the TCR V beta-chain favors the formation of a peptide that resembles the V beta 8.2-39-59 sequence. The B cell epitope present on the V beta 8-44-54 sequence was evident only in the absence of residues 39-43 and 55-59, suggesting that the two peptides possess distinct conformations. However, the V beta 8-44-54 B cell epitope is most likely expressed on the V beta 8.2+ T cells, either as a low affinity determinant on the intact TCR alpha/beta heterodimer or as a cryptic epitope bound in the cleft of surface MHC molecules.

Establishment of primary cultures of rat and human parotid epithelial cells for transfection experiments

The molecular mechanisms that regulate the synthesis of salivary proteins are unknown. The paucity of homogeneous cell populations of parotid acinar cells has become a limiting factor for such a study. Therefore, the establishment of immortalized clones of acinar cells is essential. This study has established primary cultures of rat and human parotid epithelial cells that are suitable for transfection with plasmid vectors, pSV2, pSV3, and pSV5 to generate immortalized cells in vitro. Among various techniques used, the rat and human parotid tissue or cellular clumps when restrained in chicken plasma clot allowed the outgrowth of epithelial cells that maintained epithelial cell morphology for over 4 wk. However, the initial growth requirements for rat and human parotid cells were different. The presence of 10% heat inactivated fetal bovine serum in supplemented MCDB-LB medium was essential for the outgrowth of rat parotid epithelial cells, but this was not needed for the outgrowth of human parotid epithelial cells. The growth of both human and rat parotid epithelial cells can be maintained in serum-free supplemented MCDB-LB. These primary cultures contained amylase-producing cells as demonstrated by immunofluorescent technique, and they were transfected with pSV2, pSV3, and pSV5 using primarily the calcium phosphate-DNA co-precipitation technique. After initial extensive cell death, many cells with epithelial cell morphology survived.

Inflammatory macrophages in the dog contain high amounts of intravesicular ferritin and are associated with pouches of connective tissue fibers

We have studied the subcellular distribution of ferritin in inflammatory macrophages present in regional lymph nodes from dogs subjected to a pulmonary inflammatory reaction. The inflammatory reaction was induced by intrabronchial instillation of calcium tungstate (CaWO4), a water-insoluble powder. Ferritin was identified by electron microscopy, and its electron density was enhanced by the use of a modified Perls method. From day 14 on after the CaWO4 deposition, tungsten-positive lymph node macrophages showed a massive accumulation of ferritin. Most of the ferritin was stored in membrane-bounded vesicles that showed heterogeneous concentrations of the protein. A significant complement of ferritin was also detected in the cytoplasmic ground substance of phagocytes. The cell surface of the ferritin-rich, tungsten-positive macrophages showed deep infoldings that encompassed small pockets of connective tissue fibers. These features were not observed in control samples or in lymph nodes from dogs subjected to CaWO4-induced inflammation for periods shorter than 1 week. Our data indicate that inflammatory macrophages greatly increase their content of ferritin macrophages greatly increased their content of ferritin and that ferritin is stored predominantly by a membrane-bounded vesicular compartment. This is in contrast with suggestions that the inflammation-induced increase in macrophage iron is restricted to the labile pool of iron and it does not involve the iron bound to ferritin molecules. Our observation of nodules of connective-tissue fibers in intimate topographical association with ferritin-rich macrophages may indicate that the increase in intracellular ferritin in the macrophage is in some way related to the secretion of factors by the phagocyte that will stimulate fibrillogenesis by neighboring fibroblats.

Time course and distribution of tungsten-laden macrophages in the hilar lymph nodes of the dog lung after experimental instillation of calcium tungstate into the left apical bronchus

We sprayed a tungsten powder (CaWO4) into the airway of a single lobe (left apical) of the dog lung in order to study: (a) the kinetics of particle translocation from the bronchoalveolar lining to hilar lymph nodes, and (b) the sorting in lung lymph nodes of inhaled microcrystals. We found that the transport of the tungsten particles to the regional lymph node takes at least 24 hours and reaches its peak at day 7. In situ detection of tungsten by elemental particle analysis of lymph node sections by scanning electron microscopy allowed precise mapping of the marker in the node; the method was complemented by light microscopy and thin-section electron microscopy of the same nodes. Virtually all of the lymph node tungsten was located inside macrophages. The first tungsten-positive macrophages seen in the regional lymph nodes (day 1 to day 3) were restricted to the subcapsular space. This was followed by massive filling of the same sinus and of the narrow interfollicular areas by the particle-laden macrophages (day 3 to day 7). The even distribution of the tungsten-bearing phagocytes found in these anatomical regions of the node indicated that the subcapsular area in the dog was a continuous domain rather than the segmented region observed in nodes of common laboratory animals such as the rat. By day 7 after tungsten instillation, a moderate number of tungsten-positive macrophages was also detected in the paracortical region of the node. Finally, the presence of tungsten-bearing macrophages was extended to the outer lymph node medulla (day 7 to day 14); here, the macrophages were located in association with cords of plasmacytes and showed interdigitations with these lymphocytes. Only minimal amounts of tungsten were detected inside lymphoid follicles in association with dendritic cells. Some of the tungsten initially deposited in the airway of the apical left lung lobe was detected in contralateral hilar lymph nodes. We conclude that: (i) particle translocation from the alveolus to regional lymph nodes is a slow process that is mediated by pulmonary macrophages, in agreement with the findings of Harmsen et al Science 230:1277, 1985); (ii) in the lymph node, particle-bearing macrophages are sorted through narrow interfollicular sinuses into the outer medulla where they interact extensively with plasma cells; (iii) the migrating macrophages cannot penetrate the follicular domains of the node; minute quantities of exogenous particles may, nevertheless, be transferred from macrophages to follicular dendritic cells; and (iv) contralateral drainage may be a feature of the lymphatic system in the lung.

Antibodies specific for VB8 receptor peptide suppress experimental autoimmune encephalomyelitis

Recent studies from our laboratory have shown, for the first time, that a synthetic peptide from that TCR VB chain used preferentially by encephalitogenic T cells induced the formation of protective, MHC class I-restricted T cells and prevented the development of EAE in Lewis rats. In this report we 1) demonstrate that immunization with the TCR-VB8-39-59 peptide generated peptide-specific antibodies that protect against experimental autoimmune encephalomyelitis induced by either of the two distinct encephalitogenic epitopes of basic protein, and 2) characterize the production and biologic functions of rat and rabbit antibody responses to the TCR peptide. The antibodies in both species increased in titer over time, were highly specific for the immunogen by direct reaction and inhibition assays, stained only VB8+ T cells, and suppressed clinical signs and to lesser extent the number of histologic lesions of experimental autoimmune encephalomyelitis mediated by VB8+ T cells. Coupled with our previous work, these results indicate that both humoral and cellular responses to the TCR-VB8-39-59 peptide can contribute independent immunoregulatory effects on encephalitogenic T lymphocytes that use common V region genes in response to epitopes of myelin basic protein.

Antibodies specific for VB8 receptor peptide suppress experimental autoimmune encephalomyelitis

Recent studies from our laboratory have shown, for the first time, that a synthetic peptide from that TCR VB chain used preferentially by encephalitogenic T cells induced the formation of protective, MHC class I-restricted T cells and prevented the development of EAE in Lewis rats. In this report we 1) demonstrate that immunization with the TCR-VB8-39-59 peptide generated peptide-specific antibodies that protect against experimental autoimmune encephalomyelitis induced by either of the two distinct encephalitogenic epitopes of basic protein, and 2) characterize the production and biologic functions of rat and rabbit antibody responses to the TCR peptide. The antibodies in both species increased in titer over time, were highly specific for the immunogen by direct reaction and inhibition assays, stained only VB8+ T cells, and suppressed clinical signs and to lesser extent the number of histologic lesions of experimental autoimmune encephalomyelitis mediated by VB8+ T cells. Coupled with our previous work, these results indicate that both humoral and cellular responses to the TCR-VB8-39-59 peptide can contribute independent immunoregulatory effects on encephalitogenic T lymphocytes that use common V region genes in response to epitopes of myelin basic protein.

[Effect of intravenous administration of SO4Mg in the acute phase of myocardial infarct]

Fifty four patients (p) with acute myocardial infarction (40M; 14F) were entered into a prospective study where they received either intravenous magnesium sulphate (group A-27 p) or placebo (group B-27 p). The incidence of arrhythmias necessitating treatment was greater in group B (37%) than in group A (15%). Mortality was 18.5% in group B and 3.7% in group A. These results suggest that magnesium sulphate administration reduces the incidence of arrhythmias and death after acute myocardial infarction.

[Therapeutic effectiveness of intravenous magnesium sulfate in tachyarrhythmia. Apropos of 4 clinical cases]

This is a report about four patients with tachyarrhythmias successfully treated with intravenous magnesium sulfate. In two cases (supraventricular tachycardia and torsade de pointes) because they were resistant to other antiarrhythmic drugs, and in the remaining two cases (paroxistic atrial fibrillation) because they presented characteristic features of magnesium depletion. The efficacy, the rapid onset of action and the absence of adverse reactions must be emphasized and the authors suggest that larger and randomized trials should be carried out, in order to establish the real place of magnesium sulfate in the antiarrhythmic armamentarium.

Environmental contamination by Toxocara sp eggs in public areas of Salvador, Bahia State, Brazil

A survey of parasite eggs and cysts in soil and dog feces collected in public places of 23 boroughs of Salvador, a city in the Northeast of Brazil, was performed. High degree of contamination by Toxocara sp eggs was observed in all boroughs studied; other parasites found included: Ascaris lumbricoides, hookworms, whipworms and protozoan cysts. Parks and public gardens were more contaminated than streets and beaches for all parasites, including Toxocara sp.

Alveolar septal changes in pulmonary edema: a subcellular study of lung clearance in the dog

Left lobe lung biopsies were obtained in dogs allowed to breathe in atmospheres of coal or barium sulphate dust before ligature of the left pulmonary veins and at 15 min, 1, 5, 7, 15, and 30 days after ligature. All samples were prepared for transmission electron microscopy (TEM) and scanning electron microscopy (SEM); in addition, samples from the barium sulphate group were examined by electron diffraction analysis (EDA). Two main phagocytic cell types were identified. In addition lymphatic capillary-like structures were observed in the alveolar septum after ligature of the pulmonary veins.

Experimental allergic encephalomyelitis (EAE): role of B cell and T cell epitopes in the development of EAE in Lewis rats

Studies from our laboratory have shown that classical clinical and histological signs of experimental allergic encephalomyelitis (EAE) may be induced in Lewis rats by synthetic peptides S49 or S55. Peptides S49S and S55S are defined by residues 69-84 and 72-84 of the guinea pig myelin basic protein (MBP), respectively. Peptide S53 (residues 75-84 of the guinea pig MBP), six residues shorter than S49S at the N-terminal end, induced mild clinical signs of disease unaccompanied by hind leg paralysis, incontinence, or central nervous system pathology. In contrast, peptide S67 (residues 69-81 of the guinea pig MBP), three residues shorter than S49S at the C-terminal end, did not induce either clinical or histological signs of EAE despite the fact that the S67-sequence houses an epitope known to induce cell-mediated immunity. Peptides S49S, S55S, and S53 are antigenic and gave rise to antibodies that recognized either of the three peptide sequences. In this report we explore the interrelationship between cellular immunity induced by the S67 sequence and humoral immunity, induced by the S53 sequence and the development of classical clinical and histological signs of EAE. The results show that the nonencephalitogenic sequence of S67 may be rendered encephalitogenic in the presence of antibody directed against the S53 sequence. Lewis rats immunized with S53 developed pathological signs of EAE only after they were challenged with S67. The fact that a simultaneous challenge with S67 and S53 was as effective in inducing EAE pathology as a delayed one (up to 40 days) suggests that the cellular response to S67 is dependent upon the humoral response to S53.(ABSTRACT TRUNCATED AT 250 WORDS)

Biological activity of region 65-102 of the myelin basic protein

Region 65-102 of the myelin basic protein (MBP) houses a number of antigenic determinants known to induce delayed-type hypersensitivity, experimental allergic encephalomyelitis (EAE), suppressor cell function, and antibodies. In this report we describe the biological activity of synthetic peptides S53, S55, and S49 with sequence homology to region 69-84 of the rat, guinea pig, and bovine MBP. Peptide S53-A, defined by residues 75-84 of the guinea pig (SQRSQDEN) and of the rat (SQRTQDEN) MBP induced clinical signs of disease in Lewis rats. These included weight loss, flaccid tail, "muscle wasting," and hind-leg weakness. Histological examination of brain, spinal cord, and sciatic nerve sections of diseased rats revealed the complete absence of focal and perivascular lymphocytic infiltrates characteristics of demyelinating EAE lesions. Elongation of peptide S53 by three or six residues to residue sequences naturally found at its N-terminal end gave rise to peptides S55S (PQKSQRSQDEN) and S49S (GSLPQKSQRSDQDEN), respectively. Lewis rats challenged with either S55S or S49S developed classical clinical and histological signs of EAE. Severe hind-leg paralysis was accompanied by incontinence and sometimes death. Injected in the form of carrier-free peptide, S53 was a meager B cell immunogen. S53 conjugated with methylated-bovine serum albumin was also a potent immunogen and produced clinical signs of disease without CNS pathology. By comparison, carrier-free S55S and S49S were potent immunogens giving rise to antibodies that cross reacted completely and competitively with S55S but considerably less so with S53. The results show that the sequence of S53 defines an epitope responsible for the formation of anti-S53 antibodies. Elongation of the S53 sequence at its N-terminal end generated an additional epitope which induced cell-mediated immunity responsible for the concomitant development of pathological signs of EAE. It may be concluded that the induction of classical signs of EAE requires specific and defined sequences capable of expressing both B cell and T cell functions.

The lymphatic vessels of the lung: morphological study

The authors studied the anatomical structures of the pulmonary lymphatic vessels in the dog and in man using injection techniques and macro- and microangiographic and histological methods. The results show that injection in the basal lobes is easier than in the apical lobes. The dog, an animal with a thin pleura, has a very dense superficial lymphatic network, like man. The superficial and the deep lymphatic vessels are connected through the pleural septa.

The development of experimental allergic encephalomyelitis with immunizing doses of myelin basic protein

Rabbits immunized with low (11.25 mg) and high (57.50 mg) doses of myelin basic protein from several species develop antibasic protein antibodies, delayed type hypersensitivity, and clinical and pathological signs of experimental allergic encephalomyelitis. More than 55% of rabbits immunized with relatively high doses of basic protein develop disease. The absence of circulating antibasic protein antibodies in immunorespondent animals is associated with the appearance of clinical or histological signs of experimental allergic encephalomyelitis; however, the presence of humoral antibodies did not prevent completely the development of disease. Delayed-type hypersensitivity, specific for the basic protein, appears as early as 5 days after immunization and is maintained in nondiseased and surviving animals. Neither excess encephalitogen nor encephalitogen-induced antibody is sufficient to suppress completely the eventual development of clinical or histological manifestations of disease.