Biomedical subjects

R B Fritz

Publications and source records attributed to R B Fritz.

At least 19 recordsLinked to original sources

PubMed2001

Regulation of experimental autoimmune encephalomyelitis in the C57BL/6J mouse by NK1.1+, DX5+, alpha beta+ T cells.

C57BL/6 (B6) mice with targeted mutations of immune function genes were used to investigate the mechanism of recovery from experimental autoimmune encephalomyelitis (EAE). The acute phase of passive EAE in the B6 mouse is normally resolved by partial recovery followed by mild sporadic relapses. B6 TCR beta-chain knockout (KO) recipients of a myelin oligodendrocyte glycoprotein p35-55 encephalitogenic T cell line failed to recover from the acute phase of passive EAE. In comparison with wild-type mice, active disease was more severe in beta(2)-microglobulin KO mice. Reconstitution of TCR beta-chain KO mice with wild-type spleen cells halted progression of disease and favored recovery. Spleen cells from T cell-deficient mice, IL-7R KO mice, or IFN-gamma KO mice were ineffective in this regard. Irradiation or treatment of wild-type spleen cell population with anti-NK1.1 mAb before transfer abrogated the protective effect. Removal of DX5(+) cells from wild-type spleen cells by anti-DX5 Ab-coated magnetic beads before reconstitution abrogated the suppressive properties of the spleen cells. TCR-deficient recipients of the enriched DX5(+) cell population recovered normally from passively induced acute disease. DX5(+) cells were sorted by FACS into DX5(+) alpha beta TCR(+) and DX5(+) alpha beta TCR(-) populations. Only recipients of the former recovered normally from clinical disease. These results indicate that recovery from acute EAE is an active process that requires NK1.1(+), DX5(+) alpha beta(+) TCR spleen cells and IFN-gamma.

Acute Disease↗

PubMed2000

The fate of adoptively transferred quiescent encephalitogenic T cells in normal and antigen-tolerized mice.

Adoptive transfer of quiescent encephalitogenic T cells to normal syngeneic recipients was without clinical effect. RT-PCR was used to assess localization of an adoptively transferred quiescent encephalitogenic T cell clone in normal and antigen-unresponsive mice prior to or after challenge with neuroantigen/CFA. The T cell clone was not detectable in lymphoid tissues prior to challenge with neuroantigen; however, following challenge, the clone was found in the spleen, lymph nodes and spinal cord of both normal and antigen-tolerized mice. The latter animals remained clinically normal. Non-activated encephalitogenic T cells transferred to wild-type recipients pretreated i.p. with neuroantigen/IFA were rendered unresponsive. Transfer of the same T cells to alpha/beta T cell-deficient mice pretreated with neuroantigen/IFA resulted in spontaneous disease indicating that an intact alpha/beta T cell system was required for development of the unresponsive state.

Adoptive Transfer↗

PubMed2000

Alterations in the spinal cord T cell repertoire during relapsing experimental autoimmune encephalomyelitis.

The CNS T cell repertoire was analyzed by RT-PCR, spectratyping, and nucleotide sequencing of the amplified products at different times following adoptive transfer of a CD4+, Th1, VB2+ encephalitogenic SJL/J proteolipid protein peptide 139-151-specific T cell clone. The third complementarity-determining region of TCR B chains in the spinal cord was used as an indicator of T cell heterogeneity. Spectratypic analysis revealed that a single peak corresponding to the third complementarity-determining region of the initiating T cell clone predominated during the acute phase. During recovery and relapse the complexity of the spectratype increased. DNA sequence analysis revealed that the donor clone predominated at the acute phase. By the first relapse the donor clone, although represented most frequently, was a minority of the total. Spectratypic analysis of the same samples for several other VB families revealed their presence during acute disease or relapses but, with the exception of VB17, their absence during the recovery stage.

Amino Acid Sequence↗

PubMed1999

Pathogenesis of acute passive murine encephalomyelitis II. Th1 phenotype of the inducing population is not sufficient to cause disease.

The present study was designed to assess the pattern of cytokine expression over the course of disease in the central nervous system (CNS) of recipients of an encephalitogenic T-cell clone specific for proteolipid protein (PLP) peptide 139-151. Reverse transcriptase-polymerase chain reaction (RT-PCR) analyses of CNS mRNA from samples taken during the onset of acute disease demonstrated upregulation of message for cytokines involved in the recruitment and activation of macrophages (GM-CSF, interleukin (IL)-3, IL-9) and the inflammatory cytokines tumor necrosis factor (TNF)-alpha and iNOS as well as message for IL-10 and transforming growth factor (TGF)beta. During the recovery stage message for most cytokines was absent, but during relapse inflammatory cytokine messages were again detectable. Message for the accessory molecules B7-2 and CTLA-4 was observed only on the day of onset of acute experimental allergic encephalomyelitis (EAE) and at relapse. The messages for these molecules were downregulated at the onset of recovery. These results illustrate the dynamic nature of the immune response during the course of EAE, and support a model of disease in which T-cells are involved in the regulation of disease while a nonspecific inflammatory reaction is responsible for the CNS damage observed during EAE.

Abatacept↗

PubMed1998

Persistence of an encephalitogenic T cell clone in the spinal cord during chronic, relapsing experimental autoimmune encephalomyelitis.

The CDR3 region of the TCR beta-chain of a CD4+, Th1, Vbeta2+ encephalitogenic T cell clone was used as an idiotypic marker to track the location of the clone in vivo. cDNA prepared from the spinal cord, thymus, lymph nodes, spleen, and liver of the recipients at various stages of EAE was amplified using Vbeta2 and Cbeta-region primers, and the products immobilized. The membrane was probed with a 32P-labeled oligonucleotide complementary to the CDR3 region of the T cell clone. The probe reacted strongly with products from the spinal cord, spleen and liver and less strongly with products from lymph nodes and thymus of mice with acute EAE. The signal was greatly diminished in the spinal cord and other tissues during recovery from acute disease and reappeared in the spinal cord at each relapse.

Animals↗

PubMed1998

Acute and relapsing experimental autoimmune encephalomyelitis in IL-4- and alpha/beta T cell-deficient C57BL/6 mice.

Experimental autoimmune encephalomyelitis follows a chronic relapsing course in several inbred strains of mice. To address the role of T cells in recovery and relapse, the clinical course of EAE was compared in C57BL/6 (B6) normal and immunodeficient mice following active immunization with MOG p35-55 or adoptive transfer of encephalitogenic peptide-specific T cell lines. The course of actively-induced EAE in B6 wild-type and IL-4 -/- mice was similar. B6 IL-4 -/- mice recovered normally from acute passive EAE, but did not relapse in contrast to wild-type B6 mice. EAE was progressive in B6 RAG -/- and alpha/beta TCR -/- mice, but the disease course could be arrested by infusion of normal spleen cells. When non-activated MOG peptide-specific T cells were transferred to wild-type or alpha/beta TCR -/- mice, spontaneous disease ensued in the mutants only.

Acute Disease↗

PubMed1998

Pathogenesis of acute passive murine encephalomyelitis I. Importance of host-derived cells as determined by kinetic analysis.

Kinetics of entry into the CNS of donor- and host-derived T-cells during the onset of acute murine EAE induced by the passive transfer of an encephalitogenic PLP(139-151)-specific T-cell clone was investigated. RT-PCR and spectratypic analysis of total RNA recovered from recipient mice demonstrated the presence in the CNS of donor- and host-derived T-cells 24 h post adoptive transfer. Donor-derived T-cells detected in the CNS decreased days 2-6 post transfer while host-derived T-cells persisted during this time. Beginning 3 days before clinical onset, an increase in the CNS of both T-cell populations was observed which persisted through disease onset. Similar analysis performed on recipients of an nonencephalitogenic PLP(139-151)-specific T-clone demonstrated a transient infiltration of donor- and host-derived T-cells beginning 4 days post transfer (dpt) and returning to background levels by day 7 post transfer. Results presented here suggest the importance of host-derived T-cells in the onset of acute passive murine EAE.

Acute Disease↗

PubMed1996

Thymic expression of myelin basic protein (MBP). Activation of MBP-specific T cells by thymic cells in the absence of exogenous MBP.

Previous studies have shown golli-myelin basic protein (MBP) mRNA to be expressed in the thymus of normal SJL mice, but translation of the mRNA was not assessed. To test for the presence of immunoreactive protein, single cell suspensions were prepared from adult SJL thymus and cultured with syngeneic MBP-specific T cells. After 48 h [3H]thymidine was added to the microcultures to assess T cell proliferation. MBP-specific T cell lines proliferated strongly (stimulation index range, 13-31). T cell lines specific for MBP exon 2, MBP peptide 89-101, proteolipid protein peptide 139-151, and OVA gave stimulation indices of 10-13, 5-6, 2-3, and 2-3, respectively. Stimulatory activity could be abrogated by irradiation of either the thymic cells or the MBP-specific T cells. Stimulatory activity was a property of a minor population of plastic-adherent thymic cells. Monoclonal anti-I-As Ab added to the microcultures inhibited the reaction by 77%. MBP-specific T cells cultured with syngeneic nonirradiated thymus cells in the absence of added MBP transferred experimental autoimmune encephalomyelitis adoptively to syngeneic recipients. These findings indicate that golli-MBP mRNA is translated in normal SJL thymus, and that peptides reactive with MBP-specific T cells in the context of class II MHC molecules are expressed.

Amino Acid Sequence↗

PubMed1996

Active and passive experimental autoimmune encephalomyelitis in strain 129/J (H-2b) mice.

Failure of C57BL/6J and C57BL/10Sn (H-2b) mice to exhibit clinical signs of experimental autoimmune encephalomyelitis following immunization with myelin basic protein (MBP) has been interpreted to indicate that mice of this haplotype are resistant to EAE. Recently, we immunized strain 129/J (H-2b) mice with rat MBP and found that clinical signs of EAE were expressed in the majority of animals within 2 to 3 weeks. Passive EAE was readily induced by adoptive transfer of MBP-specific T cell lines to syngeneic recipients. MBP peptide 89-101 and PLP peptide 178-191 induced EAE upon active immunization although proteolipid protein peptide 139-151 was ineffective in this regard. Strain 129/J mice never recovered fully from acute EAE, and signs of relapsing disease were not observed.

Adoptive Transfer↗

PubMed1995

Thymic expression of the golli-myelin basic protein gene in the SJL/J mouse.

The T cell antigen-specific repertoire is thought to be shaped by thymic expression of self molecules. Since a myelin basic protein (MBP)-like gene (golli-MBP) has been reported to be expressed by cells of the immune system, the present study was undertaken to determine whether the golli-MBP gene was expressed in the mouse thymus and, if so, to characterize transcripts of this gene in this organ. Using exon-specific primers for MBP and golli-MBP, cDNA from thymus and other tissues was amplified, and the amplified products analyzed by Southern blotting with exon-specific oligonucleotide probes. The amplified products were subcloned, and the inserts characterized by DNA sequencing. The thymic transcripts were found to contain golli-MBP exons 1, 2, 3, 5A, 5B, 5C, 6, 7, 8, and 11.

Animals↗

PubMed1995

The immune response to a subdominant epitope in myelin basic protein exon-2 results in immunity to intra- and intermolecular dominant epitopes.

Experimental autoimmune encephalomyelitis was induced in SJL/J mice by adoptive transfer of a MBP exon-2 peptide-specific T cell line. The T cell line, when tested for antigen specificity, reacted strongly with exon-2 peptide, but not with MBP peptides pAc1-11, p43-88, p89-101 or PLP p139-151. The specificity of splenic or lymph node T cells isolated from mice with acute or first relapse EAE induced by adoptive transfer of the exon-2-specific T cell line was identical to the transferred line. Splenocytes or lymphocytes isolated from mice at the second relapse were reactive with MBP p43-88, p89-101 and PLP p139-151 in addition to exon-2 peptide and MBP peptide Ac1-11. T cell lines selected by culture with MBP exon-2 peptide or PLP p139-151 from splenic cells from mice with relapsing EAE were weakly encephalitogenic; however, T cell lines selected from the same mice with MBP pAc1-11 were not encephalitogenic. T cells from the exon-2 and p139-151 T cell lines primed recipients for rapid onset severe EAE, whereas the pAc1-11 T cell line did not. T cells from the exon-2-specific line did not express V beta 17a+ TCR; however, peptide-specific T cell lines derived from the spleens of relapsing animals did express this TCR gene segment providing direct evidence of recruitment and sensitization of recipient T cells.

Amino Acid Sequence↗

PubMed1994

Encephalitogenicity of myelin basic protein exon-2 peptide in mice.

Immunization with a synthetic peptide with an amino acid sequence corresponding to mouse myelin basic protein exon-2 induced mild experimental allergic encephalitis (EAE) in B10.RIII mice, very mild disease in SJL/J mice and no disease in (SJL x PL)F1 hybrid mice. In contrast, adoptive transfer of an exon-2 peptide-specific T cell line from SJL mice induced severe relapsing EAE in syngeneic recipients. The T cell line was specific for exon-2 peptide and did not cross-react appreciably with an MBP preparation consisting of the 18.5 and 14-kDa isoforms. mRNA for exon-2 containing isoforms could be demonstrated in the spinal cord of SJL/J and B10.RIII mice by amplification using exon-2 and exon-4 oligonucleotide primers. On a relative basis, the level of exon-2 cDNA was lower than that of exon-1 cDNA in the same spinal cord preparations from both strains of mice.

Amino Acid Sequence↗

PubMed1994

Self-determinants in autoimmune demyelinating disease: changes in T- cell response specificity.

Recent research developments support the following views regarding antigen recognition in autoimmune demyelinating disease: there may be no single autoimmune target protein; diverse peptide self-determinants from multiple myelin proteins can be recognized; target determinant epitopes may differ among individuals; and target epitope recognition can change with time during the course of disease.

Animals↗

PubMed1993

Epitope specificity and TCR V beta gene utilization in the encephalitogenic response of B10.RIII(71NS)/SnJ mice.

A high proportion of peptide 1-11 specific T cells from H-2u (V beta 8+, H-2u) mice express the V beta 8 TCR chain. Peptide 89-101 is immunodominant for B10.RIII (V beta 8+, H-2r) mice; thus, it was of interest to determine whether V beta 8 TCR would be over-represented in a population of peptide 89-101-specific T cells of this strain. Second, it was asked whether MBP peptides other than 89-101 would induce EAE in these mice. Of 70 B10.RIII(71NS)/SnJ mice immunized with mouse myelin basic protein (MBP), 32 of 41 males (78%) and 11 of 29 females (38%) showed clinical signs of experimental allergic encephalomyelitis (EAE). All mice immunized with peptide 89-101 showed clinical signs. One of six mice immunized with peptide 91-103 showed clinical signs, and 9 of 16 mice, all males, responded with EAE when immunized with peptide 38-88. No clinical EAE was observed in mice immunized with peptide 43-67, 68-88, 55-74, 1-37 or 1-20. A peptide 89-101-specific T cell line was established. At the initial stimulation the line was 29% V beta 8+ versus 21% in normal controls, and the line did not transfer EAE adoptively. After five in vitro stimulations, the percentage of V beta 8+ T cells had increased to 54%, and the line was encephalitogenic. Encephalitogenicity was partially blocked by anti-V beta 8 monoclonal antibody. Thus, over-representation of V beta 8+ TCR by encephalitogenic peptide-specific T cells is not limited to peptide 1-11-specific T cells from H-2u mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Interleukin-3 and encephalitogenic activity of SJL/J myelin basic protein-specific T cell lines.

Myelin basic protein (MBP)-specific SJL/J T cells were cultured in normal growth medium or growth medium supplemented with 10% culture supernatant from WEHI-3 cells, a source of interleukin-3 (IL-3), or with recombinant IL-3. T cell lines cultured with IL-3 supplementation were more encephalitogenic compared to parallel lines cultured without this supplement. There was little difference in antigen-specific proliferative response or expression of cell surface markers CD3, CD4, CD8, IL-2R, or alpha/beta TCR in the parallel lines. Supernatant fluids from antigen-stimulated T cells from each cycle were tested for the presence of IL-2, IL-3, IL-4, granulocyte macrophage colony-stimulating factor (GM-CSF), tumor necrosis factor-alpha (TNF alpha/beta) and transforming growth factor-beta (TGF beta). No significant difference in IL-2, IL-4, GM-CSF, TNF alpha/beta, or TGF beta levels were seen when supplemented and unsupplemented cultures were compared. Supernatant culture fluids contained an activity that was highly stimulatory for the IL-3-dependent mouse mast cell line, MC/9. This activity was attributable to a combination of at least three factors that varied in relative concentrations throughout the course of the experiments. Based on neutralization by monoclonal antibodies, MC/9 stimulating activity in early passage lines was attributable entirely to IL-3 and GM-CSF. The fraction of the MC/9 stimulatory activity that could be neutralized by monoclonal antibody to IL-3 decreased with increasing stimulation cycle while the fraction neutralized by anti-GM-CSF antibodies remained relatively constant. At the time that the lines lost encephalitogenicity, the activity neutralizable by anti-IL-3 had dropped to low levels in the culture supernatants; however, MC/9 stimulatory activity remained present in the supernatants. This was due to GM-CSF and a third unidentified factor.

Animals↗

PubMed1992

Copolymer-1-induced inhibition of antigen-specific T cell activation: interference with antigen presentation.

Copolymer-1 (Cop-1) has been shown to inhibit in vivo development of experimental allergic encephalomyelitis (EAE) in animals and has been reported to have some therapeutic benefit in relapsing/remitting multiple sclerosis (MS). The mechanism by which Cop-1 acts in vivo is not known. The present study demonstrates that Cop-1 inhibits the in vitro response of several antigen-specific murine T cell hybridomas restricted to I-A, and to a lesser extent, I-E. The ability of human myelin basic protein (MBP)-specific T cell lines (TCL) to lyse targets in the context of three HLA-DR types associated with MS was also impaired by Cop-1. The results suggest that the observed inhibition was due to competition between Cop-1 and nominal antigen for the class II major histocompatibility complex (MHC) peptide binding site.

Animals↗

PubMed1992

Experimental allergic encephalomyelitis in susceptible and resistant strains of mice after adoptive transfer of T cells activated by antibodies to the T cell receptor complex.

Lymphoid cells from normal and myelin basic protein (MBP)-immune PL/J, SJL/J and (SJL x PL)F1 hybrid mice were activated by in vitro culture with monoclonal antibodies specific for CD3 or specific T cell receptor (TCR) V beta chains. Lymphoid cells activated in this manner from MBP-immune animals did not readily transfer experimental acute encephalomyelitis (EAE) to naive syngeneic recipients in contrast to lymphoid cells from the same source cultured with concanavalin A (ConA) or myelin basic protein (MBP). However, recipients of anti-TCR antibody-activated MBP-specific blasts showed accelerated onset and increased severity of EAE following immunization with MBP as compared to unmanipulated control animals. Anti-TCR activated cells incorporated [3H]-thymidine at a level comparable to ConA or antigen-stimulated cells and secreted interleukin (IL)-2 at comparable levels Anti-TCR activated blasts were greater than 90% positive for CD3 and alpha/beta TCR, 60% CD4+ and 30% CD8+. PL/J or (SJL x PL)F1 recipients of anti-TCR-activated spleen cells from syngeneic normal mice also had more severe EAE than control mice following immunization with MBP. Non-responder C57BL/10SnJ mice could be converted to responders by infusion of anti-CD3 or anti-V beta 8 monoclonal antibody-treated syngeneic spleen cells taken from normal syngeneic unimmunized mice.

Animals↗

PubMed1991

Intravenous drug users and AIDS: risk behaviors.

Risk-taking behaviors were studied in this assessment of 345 intravenous drug users from Baltimore, El Paso, and Denver. Over 50% reported injecting drugs daily and 70% shared needles with others, averaging 6.3 partners. In addition, 86% had shared a "cooker" and nearly 50% injected in a "shooting gallery." More than half of the males sampled had two or more sex partners, including 18% with five or more. Females averaged 19 sex partners in the preceding 6 months, with 22% reporting sex with five or more. Two-thirds of the total sample never used a condom, while only 6% always used this form of protection. On the other end of this risk continuum were those subjects who did not share needles or always cleaned their needles with an effective agent, had no sexual relations or always used a condom. Subjects following such practices could be considered low risk if they adopted safe behaviors in other associated areas of their lives. However, in an analysis of total risk, it was found that only 14 subjects (4%) practiced safe needle use and safe sex. Despite these findings, some encouraging results were seen. In an analysis of risk according to location, Baltimore subjects were significantly less at risk according to number of needle-sharing partners, borrowing needles, sharing a "cooker," injection in a "shooting gallery," cleaning needles, use of disinfectants, number of sexual partners, and use of condoms than either their cohorts in El Paso or Denver. Street outreach to modity risk behaviors among IVDUs began in Baltimore approximately 2 years prior to funding in El Paso and Denver. These results suggest that there may be a potential to moderate risk through intervention.

Acquired Immunodeficiency Syndrome↗