Search PubMed⌕ Search

Biomedical subjects

E H Eylar

Publications and source records attributed to E H Eylar.

At least 19 recordsLinked to original sources
PubMed1991

Inhibition of T cell mitogenesis by nitrofurans.

A group of nitrofurans (5-nitro-2-furaldehyde, nifuroxime, nitrofurazone, nitrofurantoin, 5-nitro-2-furoic acid and 2-nitrofuran) were evaluated for inhibition of mitogenesis (DNA synthesis) in human peripheral blood T cells. T cells, either triggered by phorbol myristate acetate (PMA) or in the presence of accessory cells, were activated with a specified mitogen [phytohemagglutin (PHA), concanavalin A (ConA), or anti-CD3] and the amount of tritiated thymidine incorporated into DNA was determined. The results obtained indicate that nitrofurans inhibit mitogenesis irrespective of activator. 5-Nitro-2-furaldehyde was much more inhibitory than the other compounds, while 2-nitrofuran was less inhibitory. When the aldehyde group (5-nitro-2-furaldehyde) was replaced by a carboxyl group (5-nitro-2-furoic acid), the inhibitory activity was also reduced greatly. These results show that while the nitro group alone confers inhibitory activity to the furan ring, the group at the 2 position is crucial. In general, the mitogenic response of purified T cells (lacking accessory cells) triggered by PMA (phorbol ester) was inhibited less than that of the T cell-accessory cell system. With the latter, 50% inhibition of T cell mitogenesis was achieved by nifuroxime, nitrofurazone, and nitrofurantoin at 45-51 and 34-39 microM with PHA and ConA respectively. When purified T cells were used, the values were 71-85 and 55-60 microM respectively. For a given drug concentration, mitogenesis was more inhibited when induced by ConA or anti-CD3 than by PHA. The importance of using a single cell system (purified T cells) was emphasized by the interesting finding that only this system showed enhancement of mitogenesis, up to 35-40% at low drug levels. With the exception of the nitrofuraldehyde, the nitrofurans at strongly inhibitory levels were only moderately cytotoxic, exhibiting 62-85% cell survival after exposure to drug for 68 hr. Our results suggest that nitrofurans inhibit T cell mitogenesis by a relatively non-toxic mechanism; these results are comparable to those obtained for mammalian cells under aerobic conditions.

Adult↗
PubMed1989

Comparison of mitogenic responses of young and old rhesus monkey T cells to lectins and interleukins 2 and 4.

Purified T cells from rhesus monkeys, like human T cells, do not show a significant mitogenic response to lectins or PMA, but when combined with PMA or accessory cells, PHA and Con A induce a vigorous mitogenic response. This response is strongly impaired in purified T cells from old rhesus monkeys compared to young T cells, from 56 to 72%, and parallels results obtained with T cell preparations containing accessory cells. Likewise, purified T cells do not respond to interleukin 2 (IL-2) or IL-4, but in the presence of PMA, a significant mitogenic response occurs in the young but not the old T cells. This response is augmented by accessory cells, but is still very deficient in the old T cells. These results show that the IL-2 independent activation of T cells triggered by IL-4, like the conventional IL-2 activation, is age impaired. The deficient response to IL-2 implies an age-related deficiency in IL-2 receptor as well in aged rhesus T cells, and may account for the less effective response of the old cells to calcium ionophore (+PMA) activation. The use of purified T cells in these studies obviate the influence of accessory cells, and thus simplify interpretation.

Age Factors↗
PubMed1989

Comparative mitogenic response of old and young rhesus monkey T cells to lectin from Erythrina cristagalli.

The lectin (EC) from the coral tree, E. cristagalli, while less mitogenic on a molar or weight basis than PHA or ConA, strongly activates both Rhesus monkey and human T cells. The optimal mitogenic concentrations for both Rhesus and human T cells are 0.25, 2.5, and 25 micrograms/ml, respectively, for PHA, ConA, and EC. Aged Rhesus T cells were profoundly suppressed in mitogenic response to EC (approx. 80%) compared to young Rhesus cells. However, in the presence of supplemental interleukin 2 (20 U/ml), the age-related defect was reversed; the average mitogenic response of the old Rhesus T cells was increased sixfold.

Aging↗
PubMed1984

Differentiation of prothymocytes induced by trypsin.

Treatment in vitro of nude mouse spleen prothymocytes with relatively low concentrations (1-50 micrograms/ml) of trypsin induce the Thy 1- to Thy 1+ conversion. The effect of trypsin was inhibited by prior heating or by addition of soybean trypsin inhibitor. The maximal effect achieved by trypsin treatment, approximately 25% conversion of spleen cells from layer B of an albumin gradient into theta-positive cells, was equivalent to that obtained with thymic hormone preparation (TP-1) at 10 ng/ml. Maximal conversion required 120 min incubation with TP-1 or trypsin. We conclude that both trypsin and TP-1 act by perturbation of a membrane receptor which can send a signal initiating the differentiation process.

Animals↗
PubMed1983

The passive transfer of severe allergic neuritis in Lewis rats with lymphoid cells preincubated with P2 protein.

The passive transfer of both clinical signs and histologic lesions characteristic of allergic neuritis was successfully performed in Lewis rats using pooled spleen and lymph node cells, or T lymphocytes therefrom, if first preincubated in petri dishes with P2 protein for 72 hr. For passive transfer, cells were taken from donors 8-16 days after sensitization with P2 protein or myelin in Freund's complete adjuvant, and administered via the tail vein; clinical signs appeared 12-13 days later. This study supports the importance of cell-mediated immunity in EAN and the antigenic role of the P2 protein.

Animals↗
PubMed1982

Studies with antisera against peripheral nervous system myelin and myelin basic proteins. I. Effects of antiserum upon living cultures of nervous tissue.

We studied the effects of antiserum against rat peripheral nervous system (PNS) myelin, rat or chicken central nervous system myelin basic protein (BP), or rabbit P2 protein from PNS myelin on myelinated cultures containing only rat dorsal root ganglion neurons and Schwann cells. While anti-PNS myelin serum consistently produced segmental PNS demyelination, anti-BP serum and anti-P2 serum did not. The culture results suggest that the myelin PNS proteins P1 (identical to basic protein from central nervous system myelin) and P2 are not exposed on the extracellular surfaces of myelin-related Schwann cells in tissue culture.

Animals↗
PubMed1982

Studies with antisera against peripheral nervous system myelin and myelin basic proteins. II. Immunohistochemical studies in cultures of rat dorsal root ganglion neurons and Schwann cells.

Antiserum against rat peripheral nervous system (PNS) myelin contained immunoglobulins which bound preferentially to the extracellular surfaces of myelin-related Schwann cells in intact cultures of dorsal root ganglion (DRG) neurons and Schwann cells, while antiserum against basic protein (BP) from central nervous system myelin or the PNS basic protein P2 did not. We demonstrate the presence of PNS myelin proteins P1 (identical to BP) and P2 by immunoperoxidase techniques in DRG cultures that had been treated to disrupt cellular membranes. These observations suggest that P1 and P2 are not exposed on the extracellular surfaces of myelin-related Schwann cells in culture. The results also support the hypothesis concerning the possible mechanisms by which anti-PNS myelin serum demyelinates DRG cultures, while anti-BP serum and anti-P2 serum do not.

Animals↗
PubMed1982

The complete amino acid sequence of the rabbit P2 protein.

P2 protein is a small basic protein (Mr = 14,820) found in peripheral nerve myelin and spinal cord myelin. There is now overwhelming evidence that P2 protein is the crucial antigen involved in the induction of experimental allergic neuritis, an autoimmune disease of the peripheral nervous system. The complete amino acid sequence of rabbit P2 protein was derived by sequence analysis of cyanogen bromide peptides and peptides obtained by proteolysis using Staphylococcus aureus V8 enzyme, trypsin, or clostripain. There are 131 amino acids and an excess of the basic amino acids lysine and arginine; histidine is absent. There are 3 highly hydrophobic regions in the P2 molecule. Probability analysis of the sequence predicts a high degree of beta structure, essentially in agreement with CD data.

Amino Acid Sequence↗
PubMed1982

Induction of allergic neuritis in rhesus monkeys.

Experimental allergic neuritis (EAN) was induced in rhesus monkey (Macaca mulatta) following sensitization with rabbit nerve (PNS) myelin in complete Freund's adjuvant (CFA) or with bovine P2 protein complexed with phosphatidyl serine (P2-lipid) in CFA. The response of monkeys receiving PNS myelin in CFA differed from the previous studies where monkeys developed clinical signs of fatal EAN within 15-20 days following sensitization. The monkeys in this study (6) showed a much longer delay (40-114 days) before the appearance of severe clinical signs, and 4 of the 6 animals survived without further attack (1 year). Monkeys (4) injected with P2-lipid (2:1 ratio; w/w) developed severe clinical signs of EAN which was fetal in 3 cases. Peripheral lymphocytes from monkeys sensitized to the P2-lipid showed a much stronger mitogeneic response to P2 protein than those from the PNS myelin-sensitized monkeys. on quantitation of the circulating anti-P2 antibodies, the P2-sensitized monkeys generally had much titers than those sensitized with PNS myelin.

Animals↗
PubMed1981

Allergic neuritis: phospholipid requirement for the disease-inducing conformation of the P2 protein.

The P2 protein, a small, highly ordered basic protein of peripheral nerve myelin, is a potent inducer of allergic neuritis in rats when complexed with phospholipids such as phosphatidylserine. Isolated P2 protein administered without lipid is a poor neuritogen, and if first oxidized with performic acid, aminoethylated in 8 M urea or heat denatured, it loses nearly all activity. When the aminoethylated or oxidized forms are combined with phosphatidylserine, however, they recover essentially full neuritogenic activity. Complexing with lipid also greatly enhances the activity of the heart denatured form. Spleen cells sensitized to the aminoethylated and heated forms of P2 protein show a pronounced mitogenic response to either of these forms as well as to the P2 protein itself, but only when sensitization is initiated with the lipid complex. These data indicate that the lipid complex reverses the distortion acquired by chemical treatment or denaturation and converts the P2 molecule into a conformation approximating that of the native P2 protein in myelin. These studies imply that the neuritogenic domain, while highly sensitive to denaturing conditions, requires interaction with phospholipids in order to attain the most favourable conformation for inducing a cell-mediated response that leads to disease.

Animals↗
PubMed1981

Allergic neuritis: a neuritogenic peptide from the P2 protein that induces disease in rats.

Peptide CN1, a large 93 residue peptide, derived from residues 21-113 of the bovine and rabbit P2 protein of sciatic nerve myelin, induces severe allergic neuritis in Lewis rats. When complexed with phosphatidylserine and tested at 50 microgram dosage in Freund's complete adjuvant, it induces severe clinical and histologic signs (cellular infiltration and demyelination of the sciatic nerve) in most animals. It is as potent in disease induction as the P2 protein on a weight basis. In contrast, when not complexed with phosphatidylserine, Peptide CN1 induced only mild clinical signs and histologic lesions in 3 of 10 rats. CNBr peptides CN2 and CN3, derived from the carboxyl and amino terminal ends, respectively, were not active. Spleen and lymph node cells from rats sensitized to Peptide CN1 responded to both P2 and Peptide CN1 in culture in the mitogenic assay. These data show that the major neuritogenic domain for the rat resides in the CN1 region.

Animals↗
PubMed1981

Antibody precipitation of lipid vesicles containing myelin proteins: dependence on lipid composition.

Antibody binding to human CNS myelin basic protein and to rabbit sciatic nerve myelin P-2 in their lipid-bound and water-soluble conformations has been investigated. 125I-labeled basic protein or P-2 was bound to the surface of liposomes (vesicles) of different acidic lipids, phosphatidylethanolamine (PE), phosphatidylserine (PS), phosphatidic acid (PA), phosphatidylglycerol (PG), and cerebroside sulfate (CBS). The antibody was prepared against aqueous solutions of basic protein and P-2. Antibody binding to the proteins in liposomes was measured by precipitation of the liposomes by using a double antibody radioimmunoassay. The amount of 125I-basic protein precipitated was lest when the protein was bound to PA and increased in the order PA less than PS less than PG less than CBS less than PE approximately equal to basic protein in solution, suggesting that the antigenic determinants were lest exposed or most altered for PA and most exposed for PE. This agreed fairly well with previously published biophysical studies that suggested that hydrophobic segments of the protein penetrated into the lipid bilayer and that this penetration decreased in the order PA approximately equal to PG greater than PS greater than CBS greater than or equal to PE. The amount of 125I-P-2 precipitated was least for PA and CBS and increased in the order PA approximately equal to CBS less than PS less than PG less than PE approximately equal to P-2 in solution. However, the differences were less than for basic protein and the effect of CBS was different for the 2 proteins. Less is known about the conformation of P-2 in these lipids but it is known that lipids increase its disease-inducing activity. These results indicate that interaction with lipid may sequester or alter the conformation of antigenic determinants such that antibody binding decreases.

Animals↗
PubMed1980

The PO glycoprotein of peripheral nerve myelin.

The PO glycoprotein, the major protein of peripheral nerve myelin, is a hydrophobic glycoprotein which can be isolated in soluble and insoluble forms from rabbit sciatic nerve myelin following extensive defatting and mid acidic extraction. The PO glycoprotein was localized exclusively in peripheral nervous system (PNS) myelin of sciatic nerve and rootlets by the immunofluorescent technique using goat anti-PO serum which showed a single precipitin band in double diffusion and did not cross-react with the myelin basic protein or P2 protein. Central nervous system (CNS) myelin from brain and spinal cord was negative by the immunofluorescent procedure. The major glycoprotein bands in PNS myelin, in addition to the PO glycoprotein at 28K, exist at 23K and 19K, as shown by gel electrophoresis in dodecyl sulfate. These glycoproteins, isolated by gel filtration in 2% dodecyl sulfate, show identity to the PO glycoprotein in their monosaccharide profile and overlapping tryptic peptides on peptide mapping. We conclude that both the 23K and 19K glycoproteins are derived from the PO glycoprotein by in situ proteolysis; the 23K glycoprotein has the identical amino terminal sequence. The 19K glycoprotein, beginning with amino-terminal methionine, is identical with the TPO glycoprotein, shown previously to originate from tryptic hydrolysis of the PO glycoprotein in isolated myelin. A tryptic glycopeptide containing 27 amino acids was isolated from the PO glycoprotein and sequenced. It contained a relatively high proportion of aspartic acid (four residues) and glutamic acid (two residues), thus exhibiting a high negative charge. We conclude that the total carbohydrate of the PO, 23K, and 19K glycoproteins does indeed exist as a single nonasaccharide moiety linked through N-acetylglucosamine to Asp-14 of the glycopeptide in a N-glycosidic linkage. These results further support the role of the PO glycoprotein as a typical amphipathic membrane protein.

Amino Acid Sequence↗