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N T Potter

Publications and source records attributed to N T Potter.

31 records · Page 2Linked to original sources
PubMed1992

Acute optic neuritis associated with immunization with the CNS myelin proteolipid protein.

Optic nerve tissue for SJL/J mice immunized with the central nervous system (CNS) myelin-specific proteolipid protein (PLP) was examined for histopathologic evidence of optic neuritis. Optic nerves isolated 17 d after immunization with PLP revealed an interstitial and submeningeal inflammatory infiltrate consisting of neutrophils and monocytes. In all cases, histologic evidence of optic nerve involvement correlated serologically with the presence of circulating anti-PLP antibodies. Control animals had no histopathologic evidence of disease or anti-PLP antibody. In many respects, the observed histopathologic profile of PLP-induced optic neuritis is similar to that associated with human inflammatory demyelinating diseases such as multiple sclerosis (MS). Because optic neuritis frequently is associated with some of the earliest clinical symptoms of MS, the acute nature of optic nerve involvement in this animal model suggests that immune recognition of the myelin PLP may play a significant role in the pathophysiology of optic nerve damage associated with sensitization to CNS-specific antigens.

Acute Disease↗
PubMed1989

Epibodies in autoimmunity: antisera against autoantibodies to the renal glomerular basement membrane react with idiotypes as well as with autoantigens.

The results reported here show that we have experimentally produced xenogeneic anti-idiotypic antibodies to rat autoantibodies specific for the renal GBM and one of its components, laminin. Cross-reactive idiotypes have been detected by anti-idiotypic antibodies (anti-Id) on autoantibodies to the GBM (anti-GBM) from rats of different strains, confirming the results obtained in other autoantibody systems. During the course of studies aimed at determining whether anti-Id were directed to the paratope of anti-GBM antibodies, we have observed the presence of anti-GBM (and anti-laminin) antibodies in rabbit sera with anti-Id. Affinity chromatography experiments suggest that anti-GBM reactions detected with our anti-Id sera may be caused by a heterogeneous combination of anti-Id. Thus, Ab2 alpha (and/or Ab2 gamma, all reacting with Ab1), Ab2 epsilon (epibodies, that bind to both Ab1 and GBM) and Ab3 (similar to Ab1 and therefore, reacting with GBM) may be present in our anti-Id sera. It has been suggested that antibodies displaying epibody properties may be involved in the mutual regulation of autoreactive clones and represent an important component of the autoimmune process.

Animals↗
PubMed1988

Immunochemical characterization of antibodies to the myelin proteolipid protein (PLP).

The immunochemical specificity of antibodies raised against the bovine myelin proteolipid protein (PLP) and a series of PLP synthetic peptides was examined by enzyme-linked immunosorbent assay (ELISA) and immunoblot analyses. Polyclonal rabbit anti-bovine PLP antibodies were cross-reactive with PLP isolated from rat, monkey, and human CNS white matter, as well as with PLP incorporated into rat myelin vesicles. Immunochemical analyses of 11 anti-peptide antisera revealed a more restrictive cross-reactivity pattern with only five of the 11 antisera, against peptides encompassing residues 48-59, 97-105, 183-193, 192-200 and 264-276, cross-reacting with bovine PLP by ELISA. Immunoblot analyses with the anti-peptide antisera demonstrated a similar recognition with four of the 11 antisera against peptides 48-59, 97-105, 192-200 and 264-276 recognizing the myelin PLP. These data suggest that, despite its strong phylogenetic conservation, multiple antigenic sites exist within the PLP molecule, and some of these determinants can be mimicked by synthetic peptides. However, the restrictive cross-reactivities of the anti-peptide antisera suggest that humoral recognition of the myelin PLP is conformationally dependent. The availability of anti-peptide antibodies of predetermined specificity, capable of recognizing the intact protein, should permit detailed examination of PLP topography in various experimental systems.

Amino Acid Sequence↗
PubMed1987

A major epitope of synthetic rabbit encephalitogen S24 disclosed through the use of a tritiated peptide probe.

The antibody recognition of synthetic rabbit encephalitogen S24 (TTHYGSLPQKG), which had been inactivated by extensive iodination, was fully restored by tritium-iodine exchange during boron hydride reduction. A highly active form of 3H-S24 was obtained by reverse-phase high-performance liquid chromatography (HPLC) purification of the crude product and could be further separated into three continuous subfractions, the latter two of which were fully active from an immunochemical point of view. A major epitope was disclosed through use of the 3H-S24 probe, which required the intact S24 peptide for its expression. Confirmation of two linear epitopes previously encountered, GSLPQK and THYGSL, was also obtained, the latter through the use of the third HPLC subfraction of 3H-S24.

Animals↗
PubMed1987

Immunochemical specificity of antisera raised against the synthetic encephalitogenic peptide SH624, residues 59-74 of the myelin basic protein.

Synthetic peptide SH624 (SHHPARTAHYGSLPQK), residues 59-74 of human myelin basic protein (MBP) was found to be encephalitogenic in the rabbit. Four antisera raised, against the peptide were employed in a liquid-phase equilibrium competitive radioimmunoassay with a series of synthetic peptide analogs of the region to probe the structural requirements of the B-cell determinant subsumed within SH624. The cross-reactivities of the four antisera with intact MBP were also examined. Immunochemical analyses of the four antisera suggested specificities directed against a conformational determinant dependent upon residues from the more phylogenetically conserved carboxyl C-terminal region, residues 65-74 (TAHYGSLPQK) of the synthetic immunogen. Peptide analogs shorter than SH624 from the C-terminal end showed no cross-reactivity with any of the reagent antisera while analogs shorter from the N-terminal end and including the encephalitogenic sequence TTHYGSLPQK, as well as, HYGSLPQK were reactive under equilibrium competitive conditions. SH624-reactive antibodies, cross-reactive with purified heterologous MBPs from 10 different species were also identified in all four reagent antisera. The results of these experiments support previous investigations demonstrating the accessibility of the encephalitogenic 65-74 region in intact MBP. They also underscore the importance of B-cell recognition of organ specific antigenic determinants with respect to MBP immunology and, in particular, the recognition of autoreactive determinants in the neighborhood of encephalitogenic centers.

Animals↗
PubMed1986

An immunochemical analysis of a myelin basic protein serum factor: cross reactivity with residues 69-71 of the rabbit encephalitogenic sequence 65-74 of myelin basic protein.

A partially purified myelin basic protein serum factor (MBP-SF), cross-reactive with residues 65-74 (TTHYGSLPQK) of myelin basic protein, has been employed in an immunochemical study to identify the nature of the cross-reacting determinant more precisely. To probe the structural requirements of this determinant, Scatchard inhibition analyses and competitive peptide inhibition radioimmunoassays were employed with a series of peptide analogs of the 65-74 region and with three different reagent antisera: a rabbit anti-rat myelin antiserum (#My05) and two antisera, one rabbit (#162) and one chicken (#66), raised against synthetic peptide S24 (TTHYGSLPQKG). Scatchard inhibition analyses with MBP-SF revealed specific inhibition of binding of 125I-S24 to #162 and #My05, but not to #66. Further delineation of the structural requirements of the cross-reactive determinant, employing a liquid-phase radioimmunoassay, revealed a unique reactivity pattern for the chicken anti-S24 antiserum which, unlike #162 and #My05, did not cross-react under high-affinity conditions with synthetic peptide S20 (GSLPQK, representing the C-terminal half of S24). This, in concert with the Scatchard data, is suggestive of the presence of a cross-reactive determinant centered around residues 69-71 of MBP.

Animals↗
PubMed1986

Heteroclitic antibodies in Fischer 344 rats to a synthetic encephalitogenic myelin basic protein peptide.

Fischer 344 rats, immunized with the synthetic encephalitogenic myelin basic protein peptide YS49 (YGSLPQKAQRPQDENG), produced heteroclitic antibodies that reacted much more extensively and with a much higher affinity with the cross-reacting encephalitogenic guinea pig sequence S49S (GSLPQKSQRSQDENG) than they did with the immunogenic YS49. On the other hand, antisera against S49S reacted in a normal manner with homologous S49S and cross-reacted only poorly with YS49. The phenomenon of heteroclisis in Fischer 344 rats correlated with the greater encephalitogenic potency of the cross-reacting entity. Kibler et al. (J. Exp. Med., 146 (1977) 1323-1331), by comparing the encephalitogenic guinea pig sequence to a less potent analog, had also previously observed what now would be termed a heteroclitic phenomenon at the T cell level in Lewis rats. In their hands, however, as well as in ours Lewis rat antisera against the encephalitogenic peptide region were much too complex to be analyzed with respect to heteroclisis. It was shown in the present experiments that by utilizing the Fischer 344 system one may also readily obtain heteroclisis at the B cell level against encephalitogenic peptides. Neither YS49 nor S49S as immunogen produced detectable antibody in Brown Norway (BN) rats with exception of two immunized with YS49. In those two cases heteroclitic antibodies were obtained that had a very low significant (greater than 3 SD above baseline) antigen binding capacity for S49S and no detectable reactivity for the homologous YS49 ligand.

Amino Acid Sequence↗
PubMed1986

Polyclonal antibodies to the encephalitogenic neighborhoods of myelin basic protein: singular affinity populations neutralized by specific synthetic peptide probes.

Specific ligand neutralization was used to probe the extent to which singular antibody affinity populations signified specific determinants in the neighborhood myelin basic protein (MBP) encephalitogens. The probes were individual members of a panel of synthetic peptide analogs subsuming encephalitogenic regions. Comparative Scatchard analyses of neutralized and unneutralized antisera helped to identify the particular peptide determinants involved in the original polyclonal antibody responses to the multiple antigenic determinants of encephalitogenic peptides. The range of affinities for an antibody population against a singular MBP peptide determinant was found to be relatively restricted while the range of affinities overall for all populations within a given antipeptide antiserum was found to be relatively wide and invariably discontinuous. Consequently, the individual discontinuous affinity populations could readily be dissected by application of the Rosenthal method of Scatchard curve analysis. It was found that the singular high affinity antibody population (5.6 x 10(7) M-1) of a Lewis rat antiserum to rat encephalitogenic GSLPQKAQRPQDENG (S49) was against a determinant near the N-terminal non-encephalitogenic end of the peptide. Only the low affinity antibody populations were found that had reactivity for determinants within the encephalitogenic region itself. The singular high affinity antibody population (5.97 x 10(7) M-1) of a rabbit antiserum to rabbit encephalitogenic TTHYGSLPQKAQGHRPQDEG (S82) was against a determinant centered about the tyrosyl residue, within the encephalitogenic region for the rabbit, but was completely cross-reactive with a specific circulating endogenous inhibitor. The results obtained with the rat and rabbit EAE sera were consistent with a previously advanced hypothesis that antibodies to determinants within encephalitogenic neighborhoods would effectively block the onset of EAE if high enough in affinity and not neutralized by an endogenous inhibitor.

Animals↗
PubMed1986

Monoclonal and polyclonal antibodies to myelin basic protein determinants.

A detailed immunochemical examination of monoclonal and polyclonal antibody responses to myelin basic protein (MBP) and its peptides has revealed the existence of as many as 27 antigenic determinants, many of them conformational. Topological mapping of the potential antigenic determinants onto a model of MBP secondary structure places these determinants within 11 separate regions of the molecule, including those portions that have been found to be encephalitogenic. MBP and its peptides, therefore, fall under the umbrella of the Multideterminant-Regulatory Model of Benjamin et al. (1984). However, in the case of MBP, multideterminant immunogenicity appears to represent mainly an escape from tight regulation through the avenue of conformational change.

Amino Acid Sequence↗
PubMed1986

Identification of an antigenic determinant within the phylogenetically conserved triprolyl region of myelin basic protein.

Synthetic peptide SP6 (RTPPPSG), comprising amino acid residues 98-103-Gly of myelin basic protein (MBP), and a series of peptide analogs were used to probe the structural requirements for antigenicity of a highly conserved region of a self protein. By means of a liquid-phase radioimmunoassay, antibody responses directed toward this determinant in both multi-specific anti-MBP and monospecific anti-peptide antisera were measured. The specificities of the antibodies present in the anti-MBP and anti-peptide antisera were examined by an equilibrium competitive inhibition radioimmunoassay by using the set of related peptides, as well as intact MBP from different species. Although the fine specificities of the reagent antisera differed, competitive inhibition analyses with intact MBP revealed a cross-reactive determinant involving residues 99-100 (Thr-Pro). This suggests that the neighborhood of the triprolyl region of MBP, despite its strong phylogenetic conservation, serves as an immunogen for humoral responses whether presented as a hapten-carrier conjugate or in the context of intact MBP. The latter supports the contention that the general antigenicity of a protein need not require sequence differences between the immunizing protein and its counterpart in the host.

Animals↗
PubMed1985

Immunochemical analysis of Lewis rat antisera to the synthetic encephalitogenic peptide S49.

Discrete populations of anti-S49 antibodies were found in the antisera of Lewis rats recovered from S49-induced experimental allergic encephalomyelitis (EAE). A potent inducer of EAE in Lewis rats, S49 is a synthetic peptide representing residues 69-84 of bovine myelin basic protein but with deletions at Gly-77 and His-78 to form an analogue of guinea pig or rat 69-84, GSLPQKAQRPQDENG. Each population within a given antiserum, as identified by Scatchard and Sipsian window analysis, was found to exhibit reactivity for a different S49 determinant, and the affinities of each population were relatively restricted and discontinuous. The high affinity populations (10(7)-10(8) M-1) were cross-reactive with YS8 (YGSLPQKAQGHRPQDENG) in equilibrium competitive inhibition reactions whereas the low affinity populations (10(5)-10(6) M-1) were reactive only with S49 and YS49 among a panel of peptide analogues. Of the YS8 cross-reactive antibodies the highest affinity (10(8) M-1) were also cross reactive with S81 (YGSLPQKAQGHRPQDEG) but not S49 (69-84-Gly), thus emphasizing the need for Tyr-68 for format stability of the determinant involved. The other YS8 cross-reactive population (10(7) M-1) was completely reactive with S49 but totally unreactive with S81 in equilibrium reactions, thus emphasizing the requirement for Asn-84 but not Tyr-68 for the determinant's topographic stability. Peptides shorter than S49 from the N-terminal end, but retaining the sequences AQRPQDEN or SQRSQDEN (suspected residence of minimal encephalitogenic determinants), reacted only under conditions of two-step non-equilibrium competitive inhibition assays. Such reactions would occur only at very low affinity (less than 10(5) M-1) with the anti-S49 antibodies. It was hypothesized that the encephalitogenic T-cell determinant for Lewis rats, although permitting B-cell responses at very low affinity, may exclude high affinity responses in susceptible animals.

Amino Acid Sequence↗