PubMed Health⌕ Search

Biomedical subjects

H Offner

Publications and source records attributed to H Offner.

At least 145 records · Page 8Linked to original sources
PubMed1987

Activation of an encephalitogenic T lymphocyte line with a cellfree supernatant containing basic protein and I region gene products.

Activation of antigen-specific T lymphocyte lines requires presentation of the relevant antigen by syngeneic accessory cells (AC) that express Class II MHC gene products. To determine if the T cell activation signal was AC associated or was shed into the medium, supernatants from rat thymic AC populations pulsed with guinea pig basic protein (GP-BP) or PPD were used to stimulate resting BP- or PPD-reactive T cell lines derived from Lewis or BN rats. Cellfree supernatants were found to stimulate the T cell lines in an antigen-specific, strain-restricted manner, reflecting the pattern of stimulation observed with intact AC used. The activity of the cellfree supernatant could be enhanced five to 20 times in the presence of activated T lymphocytes, the optimal production occurring over a 6-hr period. The cellfree T lymphocyte activation signal produced in the presence of activated T cell products contained both an antigen-specific, MHC-restricted component (85%) and an antigen-independent, mitogenic component (15%). Supernatants containing GP-BP but not bovine BP or PPD induced highly significant proliferation of the Lewis rat-derived BP-1 T lymphocyte line, and transfer of these supernatant-activated cells produced clinical signs of experimental autoimmune encephalomyelitis (EAE) and DTH reactions to GP-BP. The GP-BP component was not inhibited by either of two monoclonal antibodies directed at determinants on either side of the epitope(s) recognized by BP-1 cells. However, stimulation was inhibited by an anti-I-A but not an anti-I-E monoclonal antibody, suggesting the involvement of a Class II MHC gene product on the T cell activation signal. The supernatant activity could be separated by ultracentrifugation at 100,000 X G for 4 hr into a microsomal pellet and an ultrasupernatant, and both fractions had greatly reduced activity on resting T cells until they were reconstituted by vigorous mixing. These results suggest that T effector cells can be activated by AC-derived microsomal fragments bearing Class II antigens that associate noncovalently with processed antigen. This cellfree signal is sufficient to activate encephalitogenic T lymphocytes to transfer clinical EAE and DTH reactions without need for a direct T cell-AC interaction.

Animals↗
PubMed1987

Response of rat encephalitogenic T lymphocyte lines to synthetic peptides of myelin basic protein.

T lymphocyte lines and clones selected from Lewis rats immunized with guinea pig basic protein (GP-BP) proliferate and acquire the ability to transfer experimental autoimmune encephalomyelitis (EAE) after activation by the 68-88 peptide of GP-BP in concert with autologous I-A major histocompatibility antigens. In order to evaluate the amino acid sequence required for activation, encephalitogenic T lymphocytes were stimulated with synthetic peptides representing the 69-89, 69-84, 72-84, and 75-84 sequence of GP-BP. The three longest peptides, but not the 75-84 peptide, induced encephalitogenic lines and clones to proliferate and to transfer clinical EAE; none of the peptides, however, could activate T cell lines of a different epitope specificity. The 69-89 sequence was the most efficient of the synthetic peptides, inducing optimal stimulation comparable to GP-BP at 10 micrograms/ml. The 69-84 and 72-84 sequences induced comparable levels of stimulation at 250 micrograms/ml, but the 75-84 sequence was not active at any concentration. These results show that the 11 amino acids representing the 72-84 sequence of GP-BP are sufficient to trigger encephalitogenic T cell activity, and suggest that the 85-89 sequence may stabilize the conformation of the encephalitogenic epitope. The close association observed between proliferation and EAE transfer activities, induced in highly purified T cell populations using synthetic peptides, suggests that these two functional properties of T cells result from a common activation pathway involving a single T cell receptor specificity.

Amino Acid Sequence↗
PubMed1986

Myelin changes in the rats CNS following intraventricular injection of serum.

Normal human or rat serum administered by intraventricular injection induced demonstrable changes in the rat CNS myelin as seen from an increased recovery of dissociated myelin (DM), i.e. a myelin-related low density membrane fragments, from the tissue homogenates. The yield of DM reached a maximum on the third postinjection day and returned to the control level by day 5. In spite of the increased recovery of DM, no physico-chemical alternations in myelin isolates and no histological abnormalities in the tissue could be detected. The production of DM seems to be a sensitive index of serum-induced alteration of the myelin sheath.

Animals↗
PubMed1986

Chronic neurologic dysfunction and demyelination induced in Lewis rats by repeated injections of encephalitogenic T-lymphocyte lines.

Experimental autoimmune encephalomyelitis (EAE) in the Lewis rat is characteristically a monophasic paralytic disorder. Recovered rats are thereafter immune to EAE induced by injection of guinea pig basic protein (GP-BP) in complete Freund's adjuvant (CFA), but they are still susceptible to EAE induced by an encephalitogenic T-lymphocyte line (BP-1). Induction of active EAE or injection of a sublethal dose of activated BP-1 cells resulted in a monophasic episode of EAE, followed by recovery of normal neurologic function. Repeated challenges with activated BP-1 cells, however, induced unremitting neurologic signs marked by loss of tail tonicity and incontinence, which persisted for more than 6 months. Histologically, the spinal cord of affected rats revealed attenuation of MBP staining (demyelination) and moderate-to-extensive gliosis associated with increased size of intervening spaces. Inflammatory cell lesions, however, were notably absent. Biophysical analysis of isolated spinal cord myelin from affected rats demonstrated a distorted distribution in subfraction densities and the appearance of extra-myelin proteins in the light myelin subfraction. Immunologically, chronically affected animals were unresponsive to the encephalitogenic determinant on GP-BP, although other BP determinants elicited strong delayed type hypersensitivity (DTH) reactions in rats immunized initially with GP-BP in CFA. These data show that ongoing neurologic dysfunction can be induced in the Lewis rat by a GP-BP specific T-lymphocyte line; they suggest that unremitting clinical signs can persist in the absence both of inflammatory lesions in the CNS and of pronounced immunologic responsiveness to the encephalitogenic determinant of GP-BP.

Animals↗
PubMed1986

Antibodies against I-A and I-E determinants inhibit the activation and function of encephalitogenic T-lymphocyte lines.

Two monoclonal antibodies, OX-6 and OX-17, were used to evaluate respectively the roles of I-A and I-E major histocompatibility complex Class II gene products in the in vitro activation and subsequent function in recipient rats of encephalitogenic T-cell lines. Activation of the T-cell lines with guinea pig myelin basic protein (GP-BP) presented by accessory cells (APC) resulted in an increase in the number of blast cells in culture and was reflected by increased uptake of [3H]thymidine [( 3H]Tdy). The number of blasts recovered and [3H]Tdy uptake during activation was reduced drastically in the presence of OX-6, but to a much lesser extent in the presence of OX-17. OX-6 but not OX-17 appeared to block T-cell activation primarily by inhibiting APC function, since preincubation of APC but not T cells with OX-6 before stimulation resulted in complete inhibition of the cultures. After activation, the BP-1 T-cell line or D-9 clone transferred severe paralysis to normal recipient rats. Recipients of OX-6-treated BP-1 or D-9 T cells exhibited very mild or no signs, whereas recipients of OX-17-treated cells developed only slightly less severe experimental autoimmune encephalomyelitis (EAE) than recipients of untreated encephalitogenic control cultures. In contrast, treatment with OX-17 but not OX-6 reduced the ability of BP-reactive T cells to transfer delayed-type hypersensitivity reactions. Dermal testing with GP-BP in the ears of recipient rats just prior to onset of clinical signs decreased significantly the clinical intensity of EAE induced by activated BP-reactive T cells, but increased the clinical scores in rats which received unstimulated or OX-6-treated T cells. This potentiating effect of GP-BP was due most likely to the presentation of processed antigen to circulating BP-reactive T cells by APC in the ear. These results suggest that both the I-A and I-E gene products may contribute to the activation and subsequent function of encephalitogenic T cells, perhaps through separate mechanisms.

Animals↗
PubMed1986

Experimental autoimmune encephalomyelitis mediated by T lymphocyte lines: genotype of antigen-presenting cells influences immunodominant epitope of basic protein.

Lewis rats are susceptible to experimental autoimmune encephalomyelitis (EAE), and their T lymphocytes recognize epitopes in the 68-88 sequence of guinea pig myelin basic protein (BP). BN rats are resistant to EAE, and their T lymphocytes recognize epitopes outside of the 68-88 sequence, probably in the 43-67 portion of BP. To investigate the influence of the genome of antigen-presenting cells (APC) on the dominance of BP epitopes for T lymphocyte lines, we selected anti-BP lines from (Lewis X BN)F1 rats by using the APC of Lewis, BN, or F1 origin. We now report that the F1/Lewis and F1/F1 lines recognized the 68-88 epitopes and were highly encephalitogenic in F1 rats, whereas the F1/BN line recognized the 43-67 epitopes and was only weakly encephalitogenic. Thus, the genotype of the APC can influence the immunologic dominance for T lymphocytes of BP epitopes, and this dominance in turn can influence the expression of disease.

Animals↗
PubMed1985

Gangliosides inhibit phenotypic and functional properties of an encephalitogenic T-helper lymphocyte line.

Gangliosides were evaluated for their ability to inhibit the phenotype and function of an encephalitogenic T-helper lymphocyte line from Lewis rats (BP-1), which responds specifically to guinea pig myelin basic protein (GP-BP). After activation for 3 days with GP-BP, the BP-1 line induced a lethal form of experimental autoimmune encephalomyelitis (EAE) in recipient rats 3-6 days after intraperitoneal injection. Incubation of activated BP-1 line cells with 250 microM gangliosides for 1 hr prior to injection prevented EAE completely in 5/14 recipients and markedly reduced the severity of clinical signs and histologic lesions in the rest. Similar treatment of BP-1 cells with galactocerebroside had no inhibitory effect. Both individual and mixed gangliosides inhibited accessory cell-dependent activation of BP-1 cells with GP-BP. Gangliosides also inhibited BP-1 activation with a cell-free supernatant containing accessory cell-processed GP-BP and rat Ia molecules, suggesting that the inhibition was not restricted to accessory cell function. In addition to inhibiting antigen-dependent proliferation, gangliosides inhibited IL-2 dependent cell growth. Furthermore, individual and mixed gangliosides blocked binding of anti-T-helper cell antibody (W3/25) to the BP-1 line, while galactocerebroside, ceramide, and sialic acid had no inhibitory effect. Cell surface staining of T-total, T-non-helper, or Ia determinants was relatively unaffected by gangliosides. Taken together, the immunomodulatory properties of gangliosides on T-effector cell function lend biologic importance to the increased levels of gangliosides which have been reported in human diseases with immunoregulatory abnormalities such as multiple sclerosis, rheumatoid arthritis, and cancer.

Animals↗
PubMed1985

Delayed type hypersensitivity to gangliosides in the Lewis rat.

Systematic study of the immunologic properties of gangliosides has been hampered by the lack of a suitable assay. In this study, significant delayed type hypersensitivity reactions to gangliosides were observed in Lewis rats immunized with whole guinea pig spinal cord (GP-SC) in complete Freund's adjuvant (CFA). The reaction was manifested by an increase in ear thickness after intradermal injection of a mixture of gangliosides and methylated bovine serum albumin (mBSA). No responses were observed to either gangliosides or mBSA alone. The reaction to gangliosides increased after immunization, persisted for 48 h, and was characterized by perivascular infiltration of mononuclear cells. Further evidence for a cellular response was demonstrated by the transfer of ganglioside-specific ear swelling by cultured spleen cells. The response to gangliosides was not due to contamination with myelin basic protein (BP) since no reaction to gangliosides was observed in GP-BP/CFA-immunized rats, and no reaction to BP was observed in ganglioside/CFA-immunized rats. In BP-immunized rats, responsiveness to BP persisted after recovery from clinical EAE for at least 60 days. However, no response to gangliosides was observed in BP-immunized animals after recovery from clinical EAE, suggesting the lack of autosensitization to gangliosides due to the disease process itself.

Animals↗
PubMed1985

A myelin basic protein-specific T lymphocyte line that mediates experimental autoimmune encephalomyelitis.

A T lymphocyte line, BP-1, expressing the T helper phenotype was selected from Lewis rats immunized with guinea pig myelin basic protein (GP-BP) in complete Freund's adjuvant (CFA). The BP-1 line responded specifically to GP-BP but not to PPD after the first round of selection, and responded to rat but not human or bovine BP. When injected i.p. into histocompatible Lewis or F1 (Lewis X P2) recipients, the BP-1 line induced both clinical signs of experimental autoimmune encephalomyelitis (EAE) and delayed type hypersensitivity (DTH) reactions in ears challenged intradermally with GP-BP but not PPD. The severity of clinical signs and the degree of ear swelling were dependent on the dose of BP-1 cells injected. Both activities were detectable with as few as 0.1 X 10(6) BP-1 line cells and required prior activation of the line cells with GP-BP presented by accessory cells. Lewis rats that had recovered from EAE induced by injection of GP-BP in CFA were more susceptible than naive rats to BP-1 line-mediated disease, requiring as few as 0.03 X 10(6) line cells. Clinical EAE and DTH could be serially transferred into F1 (Lewis X P2) recipients with BP-1 cells and back to nonirradiated Lewis parents with activated splenocytes, suggesting that BP-1 cells persist in recipient rats. These results demonstrate the potent biologic activities of an autoreactive BP-specific T lymphocyte line. This line possesses properties similar to BP lines described previously as well as to culture-conditioned splenic T effector cells; thus, the data presented here bridge the gap between these two approaches for studying T effector lymphocyte functions.

Animals↗
PubMed1985

Specificity of T lymphocyte lines for peptides of myelin basic protein.

T lymphocyte lines specific for myelin basic protein (BP) can mediate experimental autoimmune encephalomyelitis (EAE), or can protect against the active induction of the disease. To investigate the antigenic fine specificity of guinea pig (GP) BP-specific T cell lines raised from different rat strains, and to determine whether functionally different T lymphocyte lines and clones recognized the same or different regions of the BP molecule, the proliferation responses of line cells were assessed after stimulation with purified peptides of GP-BP. Lewis rat T cell lines and clones selected for responses to whole GP-BP responded selectively to the 68-88 amino acid sequence of GP-BP, but not to the 1-37, 43-67, or 89-169 sequences. The region of GP-BP recognized by Lewis T cells was additionally defined to include the 75-80 amino acid sequence, because a T cell clone responded equally to GP and rat BP which differed by only one amino acid at position 79, but did not respond to human or bovine BP, which had a Gly-His insertion in this region. T lymphocyte lines derived from the F344 and PVG (Weizmann) rat strains shared the same selective response to peptide 68-88, but lines from BN rats responded to an epitope(s) outside of the 68-88 sequence. The functional capacity of the various T cell lines to mediate experimental autoimmune encephalomyelitis (EAE) or to induce resistance against EAE was independent of their specificity for the different GP-BP peptides; lines specific for epitope(s) within or excluded from the 68-88 sequence could be encephalitogenic depending on their strain of origin, and various lines specific for the 68-88 peptide could induce both disease and protection, disease only, or neither activity.

Animals↗
PubMed1984

Blood-brain and blood-spinal cord barrier permeability during the course of experimental allergic encephalomyelitis in the rat.

Experimental allergic encephalomyelitis (EAE) was induced in young male Lewis rats. Blood-brain barrier permeability to radiotracers of different molecular sizes was studied at intervals after induction using a tissue sampling technique. The results were correlated to the clinical picture and to the histological appearance of the central nervous system. Significant increase in blood-brain barrier permeability to small molecules was found to precede clinical symptoms by one day in the lumbar spinal cord and to coincide with the onset of clinical disease in other regions. In all regions, increased blood-brain barrier permeability preceded the occurrence of histological lesions (perivascular cellular infiltrates). No permeability increase to large molecules could be demonstrated.

Animals↗
PubMed1984

Immunological expression of gangliosides in multiple sclerosis and in a demyelinating model disease in rabbits.

Accumulating evidence suggests that the process of demyelination in MS might involve an autoimmune response to one or more myelin components. A combination of myelin basic protein and myelin haptens was considered as possibly enhancing a cellular or humoral autoimmune reaction in MS. In line with this motion we have used an in-vitro E-rosette assay that correlates with in-vivo delayed hypersensitivity to demonstrate specific immunologic sensitivity of lymphocytes from MS patients to polysialogangliosides. A recent report that only lymphocytes from patients in relapse, but not in remission, are primed by gangliosides, underscores the relevance of the antigenic expression of gangliosides during the active pathological phase of the disease. The antigenic capacity of gangliosides to induce upon immunization a neurological disorder featured by demyelination in the CNS was demonstrated in rabbits. This and previous reports on the induction of peripheral demyelination in rabbits immunized with gangliosides will be further analyzed to gain insight on the possible role of these myelin lipid components as targets for an autoimmune mechanism in MS.

Adult↗
PubMed1982

Elevated ganglioside concentration in serum and peripheral blood lymphocytes from multiple sclerosis patients in remission.

The ganglioside concentration in pooled serum from 20 patients with clinically definite multiple sclerosis (MS) was determined and compared with that in pooled serum from a similar number of healthy blood donors. There as a significant increase in the concentration of ganglioside-bound sialic acid from 691 +/- 57 micrograms/100 ml in the control sera to 926 +/-m 83 micrograms 100 ml in MS patients' sera. The profile of individual gangliosides in the two groups was identical, the four main structures being GM3, GD3, and GD1a and GT1b. The ganglioside pattern and concentration in peripheral blood lymphocytes derived from MS patients and controls was identical with the predominant GM3, and small proportions of Gd3. MS lymphocytes also showed a 39% increase in ganglioside content over control lymphocytes. The implication of such pronounced ganglioside increases is discussed with regard to the impaired immunocompetence of lymphocytes reported in MS.

Adult↗
PubMed1982

Abnofmalities in brain myelin or rabbits with experimental autoimmune multiple sclerosis-like disease induced by immunization to gangliosides.

An experimental autoimmune multiple sclerosis-like disease (EAMSD) was induced in rabbits by immunizing them with bovine brain gangliosides. Forebrain myelin was isolated and fractionated on a discontinuous sucrose gradient into light myelin (LM, buoyant density less than or equal to 0.625 M), and heavy myelin (HM, buoyant density greater than 0.625 M). No abnormalities in either protein or lipid composition of EAMSD myelin fractions were observed. However, the EAMSD tissue yielded 31% less light and 39% more heavy myelin compared to the control brains. Thus, the HL/LM ratio was two-fold greater in experimental than in control myelin. This pathological pattern is similar to that which has been observed in myelin obtained from the brains of multiple sclerosis patients and from the optic nerves of rabbits with experimentally-induced demyelination.

Animals↗
PubMed1981

Lymphocyte stimulation by gangliosides, cerebrosides and basic protein in juvenile rheumatoid arthritis.

Peripheral blood lymphocytes from patients with juvenile rheumatoid arthritis (JRA), patients with neurological diseases (ND) and healthy children were tested for reactivity to gangliosides, cerebrosides and basic protein (BP) by the active E-rosette test (AER). None of the lymphocytes from ND patients, healthy children or two children with psoriatic arthritis responded by increased rosette formation to gangliosides, cerebrosides and BP. Lymphocytes from all 16 children with JRA were sensitized to at least one antigen as shown by the AER test. The percentage of active T-cells was significantly lower (p less than or equal to 0.05)( in children with JRA as compared to others. The significance of the results in relation to immunopathogenesis of JRA is discussed.

Adolescent↗