Outcomes Post Thrombolysis for Acute Pulmonary Embolism.

Background Pulmonary embolism (PE) remains a significant cause of mortality in Europe1. Thrombolytic therapy is often utilised as a therapeutic strategy in massive and sub-massive PE. There is a dearth of research on short term complications and subsequent outcomes in patients who have received thrombolysis for PE in Ireland. Methods This retrospective study examined patients who underwent thrombolysis for acute sub massive PE whilst under the care of the respiratory service in Cork University Hospital (CUH) from 2010-2018. All patients had CTPA done for diagnosis of PE. Alteplase was used as a thrombolytic agent. Patient records were perused. Follow-up pulmonary functions tests (PFTs) and trans-thoracic echocardiogram (TTE) results were assessed for evidence of impairment of diffusing capacity (DLCO) and pulmonary hypertension (PH) respectively. Results Twenty five patients were included in the study. Nine patients (36%) were women and 64% men. Average age was 55.1 years. Four patients suffered complications related to thrombolysis (average age 63.3 years). Twenty-Two patients (88%) underwent a follow-up echocardiography (mean 30 weeks post PE). Three patients (13%) had echocardiographic evidence of possible mild PH (i.e. RVSP >40mmhg) at initial follow-up. Fourteen patients (56%) who underwent thrombolysis had follow-up PFTs (mean 11.8 months post PE). The diffusing capacity (DLCO) was normal in all patients. Conclusion Thrombolysis was a relatively safe intervention in this small study.

Sustained efficacy of the novel topical repellent TT-4302 against mosquitoes and ticks.

Mosquitoes and ticks are blood-feeding pests of humans and animals that can vector many important aetiological agents of disease. Previous research demonstrated that TT-4302 (Guardian(®) Wilderness) containing 5% geraniol applied to human subjects gave 5-6 h of repellency against mosquitoes (depending on species) and was repellent to ticks in vitro. This study was conducted to obtain an independent third-party evaluation of TT-4302 against Stegomyia aegypti (= Aedes aegypti) (Diptera: Culicidae) mosquitoes and to test the efficacy of the product in the field against ticks. TT-4302 provided an average of 6.5 h of repellency of ≥ 95% [Weibull mean protection time: 7.4 h, 95% confidence interval (CI) 5.8-11.3 h] for St. aegypti, whereas a 15% DEET formulation provided 4.7 h of repellency (Weibull mean protection time: 5.2 h, 95% CI 3.7-6.9 h). In tick field trials, the efficacy of TT-4302 did not differ significantly from that of a 25% DEET formulation against Amblyomma americanum (Ixodida: Ixodidae). TT-4302 was 81.3% repellent at 2.5 h after application, whereas DEET was 77.2% repellent at the same time-point. Results at 3.5 h after application were 71.4% for TT-4302 and 72.9% for DEET.

Performance of the plant-based repellent TT-4302 against mosquitoes in the laboratory and field and comparative efficacy to 16 mosquito repellents against Aedes aegypti (Diptera: Culicidae).

Repellent efficacy of the plant-based repellent, TT-4302 (5% geraniol), was compared with 16 other products in laboratory arm-in-cage trials against Aedes aegypti (L). Eight repellents (Badger, BioUD, Burt's bees, California Baby, Cutter Natural, EcoSMART, Herbal Armor, and SkinSmart) exhibited a mean repellency below 90% to Ae. aegypti at 0.5 h after application. Three repellents (Buzz Away Extreme, Cutter Advanced, and OFF! Botanicals lotion) fell below 90% repellency 1.5 h after application. TT-4302 exhibited 94.7% repellency 5 h posttreatment, which was a longer duration than any of the other repellents tested. The positive control, 15% DEET (OFF! Active), was repellent for 3 h before activity dropped below 90%. Additional arm-in-cage trials comparing TT-4302 with 15% DEET were carried out against Anopheles quadrimaculatus Say. At 6 h after treatment, TT-4302 provided 95.2% repellency while DEET exhibited 72.2%. In North Carolina field trials, TT-4302 provided 100% repellency 5 h after application against Aedes albopictus Skuse while DEET provided 77.6% repellency. These results demonstrate that TT-4302 is an efficacious plant-based repellent that provides an extended duration of protection compared with many other commercially available products.

Activity of the plant-based repellent, TT-4302 against the ticks Amblyomma americanum, Dermacentor variabilis, Ixodes scapularis and Rhipicephalus sanguineus (Acari: Ixodidae).

The plant-based repellent TT-4302 (5 % geraniol) was compared to deet (15 %) in laboratory two-choice bioassays against the ticks Amblyomma americanum, Dermacentor variabilis, Ixodes scapularis, and Rhipicephalus sanguineus. At 2.5 and 3.5 h after treatment of filter paper with TT-4302, 100 % repellency was observed for all species at both time points with the exception of I. scapularis at the 3.5 h evaluation where repellency was 95.8 %. Deet was 100 % repellent at both time points for D. variabilis and R. sanguineus and was 100 % repellent at the 2.5 h evaluation for I. scapularis. Repellency of deet to A. americanum was 88.9 and 95.8 % at 2.5 and 3.5 h, respectively which was not significantly different than that of TT-4302. No significant difference against I. scapularis was observed between TT-4302 and deet at 3.5 h after treatment where deet was 87.5 % repellent. A variant of TT-4302, TT-4228 was tested in the laboratory against A. americanum and was compared to deet (15 %) in field trials against wild populations of ticks in North Carolina, USA. In the laboratory, TT-4228 was 94.4 and 87.5 % repellent at 2.5 and 3.5 h after treatment, respectively. In the field where the predominant tick species was A. americanum, significantly fewer ticks were collected from socks worn by human volunteers that were treated with TT-4228 compared to those treated with deet 2.5 or 3.5 h after treatment. Significantly fewer ticks were recovered from socks treated with TT-4228 than their paired untreated controls 2.5 or 3.5 h after treatment and repellencies were 90 and 70 %, respectively. Fewer ticks were collected from deet-treated compared to their paired untreated socks 2.5 h after application; however, no significant difference was found in the number of ticks collected from deet-and untreated socks 3.5 h after treatment.

Reversible defects in natural killer and memory CD8 T cell lineages in interleukin 15-deficient mice.

C57BL/6 mice genetically deficient in interleukin 15 (IL-15(-/-) mice) were generated by gene targeting. IL-15(-/-) mice displayed marked reductions in numbers of thymic and peripheral natural killer (NK) T cells, memory phenotype CD8(+) T cells, and distinct subpopulations of intestinal intraepithelial lymphocytes (IELs). The reduction but not absence of these populations in IL-15(-/-) mice likely reflects an important role for IL-15 for expansion and/or survival of these cells. IL-15(-/-) mice lacked NK cells, as assessed by both immunophenotyping and functional criteria, indicating an obligate role for IL-15 in the development and functional maturation of NK cells. Specific defects associated with IL-15 deficiency were reversed by in vivo administration of exogenous IL-15. Despite their immunological defects, IL-15(-/-) mice remained healthy when maintained under specific pathogen-free conditions. However, IL-15(-/-) mice are likely to have compromised host defense responses to various pathogens, as they were unable to mount a protective response to challenge with vaccinia virus. These data reveal critical roles for IL-15 in the development of specific lymphoid lineages. Moreover, the ability to rescue lymphoid defects in IL-15(-/-) mice by IL-15 administration represents a powerful means by which to further elucidate the biological roles of this cytokine.

Binding of interleukin-18 to the interleukin-1 receptor homologous receptor IL-1Rrp1 leads to activation of signaling pathways similar to those used by interleukin-1.

Interleukin-18 (IL-18) is an inflammatory cytokine that has been shown to enhance a variety of Th1 type T cell responses. Because IL-18 is homologous to IL-1, we tested binding of IL-18 to the known IL-1R family members. We could show binding of IL-18 to the orphan receptor IL-1Rrp1 but not to other IL-1R homologous proteins. IL-1Rrp1 and IL-1RI share highly conserved domains within their cytoplasmic regions. Comparison of the IL-1 and IL-18 signaling mechanisms showed that they activate identical cytoplasmic messengers. IL-18, like IL-1, induced association of its receptor with IRAK and subsequent recruitment of TRAF6. IL-18 activated p38 MAP kinase, jun kinase, and beta casein kinase (TIP kinase), an apparently novel kinase previously thought to be specifically activated by IL-1 and tumor necrosis factor (TNF). IL-18 activated NF-kappaB in EL4/6.1 thymoma cells but not in COS-7 cells, even though the latter presumably contain all components required for the IL-1 signaling pathway. From our binding and signaling studies, we conclude that the IL-18 receptor complex consists of IL-18, the IL-1Rrp1, and another thus far unidentified receptor molecule.

Monoclonal antibody-induced inhibition of relapsing EAE in SJL/J mice correlates with inhibition of neuroantigen-specific cell-mediated immune responses.

Relapsing experimental allergic encephalomyelitis (R-EAE) in SJL/J mice was examined in relation to the development of neuroantigen-specific T cell proliferative (Tprlf) and delayed-type hypersensitivity (DTH) responses. R-EAE was induced by injecting syngeneic mouse spinal cord homogenate in CFA on days 0 and 7 over the shaved flanks of female SJL/J mice. Mice primed in this manner exhibited significant Tprlf and DTH responses specific for both major myelin proteins, myelin basic protein (MBP) and proteolipid protein (PLP). A time course comparison between the induction of R-EAE and the development of neuroantigen-specific cell-mediated immune (CMI) responses (Tprlf and DTH) revealed that the MBP- and PLP-specific Tprlf and DTH responses peaked prior to the onset of initial clinical symptoms and the DTH responses remained at significant levels throughout the relapsing course of the disease. Monoclonal antibodies were used to determine whether in vivo inhibition of class II-restricted Tprlf and DTH responses correlated with inhibition of R-EAE. In vivo administration of a total of 100 micrograms anti-L3T4 antibody, but not anti-Lyt-2 antibody, resulted in delayed onset and reduced severity of clinical signs of R-EAE concomitant with significantly reduced levels of MBP- and PLP-specific Tprlf and DTH responses. Treatment with a total of 300 micrograms of purified anti-L3T4 resulted in total abrogation of R-EAE induction and neuroantigen-specific CMI. Thus, clinical signs of R-EAE were found to correlate with the activity of neuroantigen-specific, class II-restricted T cells.

Induction of active and adoptive relapsing experimental autoimmune encephalomyelitis (EAE) using an encephalitogenic epitope of proteolipid protein.

Proteolipid protein (PLP) is a major component of the central nervous system (CNS) myelin membrane and has been shown to induce acute experimental autoimmune encephalomyelitis (EAE) in genetically susceptible animals. Here we describe conditions by which a relapsing-remitting form of EAE can be reliably induced in SJL/J mice either actively immunized with the major encephalitogenic PLP peptide, PLP13-151(S), or following adoptive transfer of PLP139-151(S)-specific T cells. The disease follows a reliable relapsing-remitting course with acute clinical signs first appearing 6-20 days after priming or transfer and relapses first appearing at 30-45 days. The initial onset of disease correlates with delayed-type hypersensitivity (DTH) reactivity specific for PLP139-151(S), in the apparent absence of T cell reactivity to the major myelin basic protein (MBP) peptide. Histologically, both the active and adoptive forms of the disease are characterized by extensive mononuclear cell infiltration and severe demyelination of the CNS. These results suggest that T cell responses specific for PLP139-151(S) are sufficient to induce clinical and histological R-EAE in SJL/J mice. This model should prove useful for examination of the cellular and molecular events involved in clinical relapses and perhaps in determining the role of PLP-specific T cell responses in multiple sclerosis (MS).

Class II-restricted T cell responses in Theiler's murine encephalomyelitis virus (TMEV)-induced demyelinating disease. III. Failure of neuroantigen-specific immune tolerance to affect the clinical course of demyelination.

Intracerebral inoculation of Theiler's murine encephalomyelitis virus (TMEV) into susceptible mouse strains produces a chronic demyelinating disease in which mononuclear cell-rich infiltrates in the central nervous system (CNS) are prominent. Current evidence strongly supports an immune-mediated basis for myelin breakdown, with an effector role proposed for TMEV-specific, major histocompatibility complex (MHC) class II-restricted delayed-type hypersensitivity (DTH) responses in which lymphokine-activated macrophages mediate bystander demyelination. The present study examined the possibility that concomitant or later-appearing neuroantigen-specific autoimmune T cell responses, such as those demonstrated in chronic-relapsing experimental allergic encephalomyelitis (R-EAE), may contribute to the demyelinating process following TMEV infection. T cell responses against intact, purified major myelin proteins (myelin basic protein (MBP) and proteolipid protein (PLP], and against altered myelin constituents were readily demonstrable in SJL/J mice with R-EAE, but were not detectable in SJL/J mice with TMEV-induced demyelinating disease. TMEV-infected mice also did not display T cell responses against the peptide fragments of MBP(91-104) and PLP(139-151) recently shown to be encephalitogenic in SJL/J mice. In addition, induction of neuroantigen-specific tolerance to a heterogeneous mixture of CNS antigens, via the i.v. injection of syngeneic SJL/J splenocytes covalently coupled with mouse spinal cord homogenate, resulted in significant suppression of clinical and histologic signs of R-EAE and the accompanying MBP- and PLP-specific DTH responses. In contrast, neuroantigen-specific tolerance failed to alter the development of clinical and histologic signs of TMEV-induced demyelinating disease or the accompanying virus-specific DTH and humoral immune responses. These findings demonstrate that TMEV-induced demyelinating disease can occur in the apparent absence of neuroantigen-specific autoimmune responses. The relationship of the present results to the immunopathology of multiple sclerosis is discussed.

Specific immunoregulation of the induction and effector stages of relapsing EAE via neuroantigen-specific tolerance induction.

The effects of neuroantigen-specific tolerance on the induction and effector stages of relapsing experimental autoimmune encephalomyelitis (R-EAE) were examined. The incidence of clinical and histologic signs of active MSCH-induced R-EAE, and accompanying neuroantigen-specific DTH responses, were dramatically reduced in SJL/J mice tolerized via the i.v. injection of syngeneic splenocytes coupled with MSCH, PLP, or encephalitogenic PLP peptides 7-14 days before priming. MBP-specific tolerance was not effective in preventing active R-EAE. In contrast to MSCH-induced active R-EAE, treatment of recipient mice with splenocytes coupled with MBP and the encephalitogenic MBP 84-104 peptide, but not with PLP, suppressed of clinical signs of adoptive R-EAE mediated by MBP-specific effector T cells in a dose-dependent manner. Neuroantigen-coupled splenocytes were also efficient in treating established disease as tolerization of SJL/J mice after the first incidence of clinical disease significantly reduced the incidence and severity of subsequent paralytic relapses. Antigen-specific tolerance thus provides a powerful approach for the prevention and/or treatment of autoimmune disease.

Characterization of interleukin-15 (IL-15) and the IL-15 receptor complex.

IL-15 interacts with a heterotrimeric receptor that consists of the beta and gamma subunits of the IL-2 receptor (IL-2R) as well as a specific, high-affinity IL-15-binding subunit, which is designated IL-15R alpha. Since both the beta and the gamma subunits of the IL-2R are required for signaling by either IL-2 or IL-15, it is not surprising that these cytokines share many activities in vitro. However, the differential expression of these cytokines and the alpha chains of their receptors within various tissues and cell types suggests that IL-2 and IL-15 may perform at least partially distinct physiological functions. The production of IL-15 by macrophages, and possibly other cell types, in response to environmental stimuli and infectious agents suggests that IL-15 may play a role in protective immune responses, allograft rejection, and the pathogenesis of autoimmune diseases.

Mechanisms of genetic control of immune responses. II. Nonresponsiveness in BALB/c GT-specific cell-mediated immune responses does not correlate with the absence of functional T cells or the induction of suppressor T cells.

The mechanisms underlying Ir gene control of CMI were addressed by examining the DTH and Tprlf responses specific for the synthetic polymers GT, GAT, and GA. We show that BALB/c mice (GAT/GA responders, GT nonresponders) primed with GT fail to develop DTH and Tprlf responses specific for GT, GAT, or GA. GAT immunization resulted in DTH responses that could be elicited not only with GAT and GA but also with GT, demonstrating that GT-specific TDH are present in nonresponder mice. GT-specific DTH was transferred with Thy-1+ Lyt-1+2-, H-2 I-restricted, nylon wool nonadherent cells. GA-primed BALB/c mice developed GAT- and GA-, but not GT-specific DTH responses, indicating that GA and GT do not cross-react at the T-cell level. The ability of GAT [but not a mixture of GA plus GT, or GT electrostatically complexed to the immunogenic carrier MBSA (GT-MBSA)] to induce GT-specific DTH suggested a requirement for covalent linkage of stimulatory 'GA' and nonstimulatory 'GT' determinants present on the GAT molecule. Similarly, GT-specific in vitro Tprlf responses could be demonstrated in GAT-primed mice exhibiting significant levels of GT-specific DTH but not in GT- or GT-MBSA-primed mice. Tolerization experiments also suggested that GT-specific Th were involved in the development of GT-specific DTH in GAT-primed mice. The GT nonresponsiveness of BALB/c mice for DTH and Tprlf responses could not be reversed by treatments designed to abrogate Ts activity (priming with GT-MBSA and CY injection), nor could GT-primed cells be shown to inhibit the development or elicitation of GT-specific CMI in GAT-primed mice during the afferent and/or efferent stages of DTH. Our results suggest that GT nonresponsiveness does not result from the absence of GT-specific T cells or preferential induction of Ts. The results are discussed in the context of hole-in-the-repertoire and antigen presentation (determinant selection) models of Ir gene control.

Regulation of the effector stages of experimental autoimmune encephalomyelitis via neuroantigen-specific tolerance induction. II. Fine specificity of effector T cell inhibition.

Ag-specific tolerance induced by the i.v. administration of splenocytes coupled with mouse spinal cord homogenate, containing a mixture of myelin Ag, dramatically inhibits development and expression of clinical and histologic signs of both active and adoptive forms of relapsing experimental autoimmune encephalomyelitis (R-EAE) in the SJL/J host. Here we examined the dose-dependency, route of tolerogen administration, and fine neuroantigen specificity of inhibition of adoptive R-EAE. Expression of clinical R-EAE induced by a polyclonal population of bovine myelin basic protein (MBP)-specific effector T cells was dramatically inhibited in a dose-dependent manner following the i.v., but not s.c. or i.p., injection of MBP-coupled splenocytes. The exquisite Ag specificity of the inhibition was evident by the observation that splenocytes coupled with intact bovine MBP or species variants of MBP homologous with bovine MBP within the major encephalitogenic region (amino acids 84-104), but not with proteolipid protein or mouse kidney homogenate, were able to suppress disease expression. Splenocytes coupled with the MBP84-104 peptide, containing a nested set of the major SJL/J encephalitogenic epitopes, completely inhibited peptide-specific T cell responses, but only partially inhibited the expression of disease transferred by T cells specific for intact MBP, suggesting the participation of T cell responses specific for additional MBP determinants in disease pathogenesis. However, splenocytes coupled with previously identified minor SJL/J encephalitogenic epitopes (MBP91-104 or MBP17-27), or with the Lewis rat major encephalitogenic epitope (MBP68-86), did not suppress disease expression. Collectively, the results demonstrate that MBP84-104-specific T cells and T cells specific for an as yet unidentified MBP epitope(s) contribute to the pathology of R-EAE. In addition, the results demonstrate that peptide-specific tolerance induction appears to have potential for the treatment of T cell-mediated inflammatory diseases.

Successful treatment of paralytic relapses in adoptive experimental autoimmune encephalomyelitis via neuroantigen-specific tolerance.

We have previously demonstrated that Ag-specific tolerance induced by the i.v. administration of splenocytes coupled with neuroantigens, such as mouse spinal cord homogenate, myelin basic protein (MBP), and proteolipid protein, and their encephalitogenic peptides, results in dramatic inhibition of clinical and histologic signs of both actively induced and adoptively transferred relapsing experimental autoimmune encephalomyelitis (R-EAE). We report here that the administration of splenocytes coupled with mouse spinal cord homogenate (i.e., a mixture of neuroantigens), after the first paralytic episode of adoptive R-EAE triggered by MBP-specific T cells but before the appearance of the first relapse, effectively reduced the onset and severity of all subsequent relapses, as determined by both clinical and pathologic criteria. In contrast, the i.v. administration of splenocytes coupled with MBP (i.e., the specificity of the initiating T cell response), under similar conditions, effectively inhibited the initial clinical relapse, but subsequent relapses occurred with the same incidence rate and severity as those in control animals. Collectively, these results demonstrate that neuroantigen-specific tolerance is effective at specifically down-regulating an ongoing autoimmune response. This may have potential clinical applicability for treatment of autoimmune diseases. The results also support the hypothesis that the neuroantigen specificity of later relapses of R-EAE may be due to effector T cells with specificities different from those that triggered the initial clinical episode. Thus, potential therapy for the advanced stages of R-EAE, and perhaps other autoimmune diseases, may have to be directed not simply against the effector cells initiating the disease but also against effector cells with differing specificities recruited as a result of tissue damage occurring in the initial acute disease.

Differential permeability of the BBB in acute EAE: enhanced transport of TNT-alpha.

Impairment of the blood-brain barrier (BBB) in experimental autoimmune encephalomyelitis (EAE) has been frequently attributed to disruption, without much consideration of saturable transport processes. In mice with EAE, we studied the permeability of the BBB to radioactively labeled albumin and sucrose, markers of BBB disruption, and tumor necrosis factor-alpha (TNF-alpha), a cytokine transported across the BBB by a saturable system and thought to play a role in the pathogenesis of EAE. Permeation of the BBB was increased to all three substances during the acutely ill stage, was greatest in the lumbar spine, and returned to normal with recovery. The change in BBB permeability to sucrose was greater than to the larger albumin and is consistent with a partial disruption of the BBB. The enhanced permeability to TNF-alpha was comparable to that for sucrose, even though TNF-alpha is similar in size to albumin. This paradoxically high uptake of TNF-alpha could be explained by an enhancement of its endogenous saturable transport system. Thus the changes in BBB function during EAE extend beyond disruption to include changes in the saturable transport systems for substances involved in the disease process.

Regulation of the effector stages of experimental autoimmune encephalomyelitis via neuroantigen-specific tolerance induction.

Intravenous administration of neuroantigen-coupled syngeneic splenocytes is an efficient regimen for Ag-specific regulation of relapsing experimental autoimmune encephalomyelitis (R-EAE) at the effector level of the disease process. Treatment of SJL/J mice with splenocytes coupled with mouse spinal cord homogenate (MSCH) or myelin proteolipid protein after immunization with mouse spinal cord homogenate in CFA, but before the onset of clinical signs specifically inhibited the expression of neuroantigen-specific delayed-type hypersensitivity responses and significantly suppressed the onset, severity, and the duration of clinical and histologic signs of R-EAE. In contrast, the clinical course of R-EAE was not affected by tolerization with myelin basic protein-coupled splenocytes, indicating that proteolipid protein-specific responses play the major role in active MSCH-induced R-EAE. To ensure a physical and temporal separation between the inductive and effector stages of the disease process, we also examined the effects of neuroantigen-coupled splenocytes on adoptive R-EAE. Treatment of recipient mice with MSCH-coupled splenocytes up to 6 days after the transfer of MBP-primed lymph node cells induced a dose-dependent, profound, and long-lasting inhibition of clinical and histologic signs of adoptive R-EAE. The demonstration that splenocytes coupled with a heterogeneous mixture of neuroantigens (i.e., MSCH) can inhibit established immune responses suggests that this methodology has potential for regulating ongoing immune responses associated with autoimmune disorders or chronic graft rejection in which the specific (auto)Ag has yet to be identified.

Specific immune regulation of chronic-relapsing experimental allergic encephalomyelitis in mice.

These studies were designed to examine immunologic means of regulating the clinical course of murine chronic-relapsing experimental allergic encephalomyelitis (R-EAE). We asked whether induction of specific immune tolerance to the major CNS myelin proteins, myelin basic protein (MBP) and proteolipid protein (PLP), could inhibit the development of R-EAE. Neuroantigen-specific tolerance was induced in SJL/J mice in a dose-dependent manner by the i.v. injection of mouse spinal cord homogenate-coupled syngeneic splenocytes (MSCH-SP) on day -7 relative to immunization on days 0 and +7. Sham-tolerized controls developed significant MBP- and PLP-specific DTH responses before the onset of clinical R-EAE. In contrast, MSCH-SP tolerized mice exhibited a dramatically reduced incidence of clinical and histologic signs of disease which correlated with the failure to develop MBP- and PLP-specific DTH responses. In 10 separate experiments, 118/149 (79%) of control mice, but only 22/137 (16%) of tolerized mice developed clinical R-EAE. Tolerance took time to develop and lasted at least 4 wk as mice injected with Ag-coupled splenocytes on day -1 relative to immunization remained susceptible to R-EAE, whereas mice injected on days -7, -14, or -28 were resistant. Tolerance induction required neuroantigens as injection of splenocytes coupled with a syngeneic mouse kidney homogenate failed to significantly alter the incidence of R-EAE or the development of neuroantigen-specific DTH responses. Thus, induction of R-EAE can be specifically and significantly regulated after the i.v. injection of splenocytes coupled with a crude, heterogeneous mixture of neuroantigens (i.e. MSCH).

Analysis of cytokine mRNA expression in the central nervous system of mice with experimental autoimmune encephalomyelitis reveals that IL-10 mRNA expression correlates with recovery.

Experimental autoimmune encephalomyelitis (EAE) serves as an important animal model for understanding the events that lead to immune-mediated inflammation and tissue destruction within the central nervous system. We have utilized a murine adoptive transfer model of EAE and semiquantitative reverse transcriptase-polymerase chain reaction analysis to examine cytokine mRNA expression within the central nervous system in relation to the onset and resolution of paralysis associated with EAE. Spinal cord samples, obtained from mice as they progressed through discrete clinical stages of EAE, were examined for the expression of six cytokine genes (IL-1 alpha, IL-2, IL-4, IL-6, IL-10, and IFN-gamma). Distinct patterns of cytokine gene expression were observed during the acute, recovery, and chronic phases of EAE. The acute phase of disease was characterized by rapid increases in the levels of mRNA for IL-2, IL-4, IL-6, IFN-gamma, and IL-1 alpha. In fact, peak expression of several cytokine mRNA (e.g., IL-2, IL-4, IL-6, and IFN-gamma) occurred before the peak in clinical severity. In contrast, IL-1 alpha mRNA levels were elevated throughout the initial disease course. IL-10 mRNA demonstrated only modest increases during the acute phase of EAE. Stabilization of the clinical symptoms was characterized by rapid declines in the mRNA levels of IL-2, IL-4, IL-6, and IFN-gamma. The decreases in these four cytokine mRNA levels occurred concomitant with a dramatic rise in IL-10 mRNA. Finally, of the six cytokine mRNA examined, only IL-1 alpha, IFN-gamma, and IL-10 mRNA remained elevated during the early chronic stage. These results suggest that local cytokine production varies significantly during the course of EAE and that increases in discrete sets of cytokines are associated with the acute response and the recovery/chronic phase of disease.

Interleukin-12 regulates the proliferation of Th1, but not Th2 or Th0, clones.

Our results indicate that interleukin (IL)-12 is an important costimulator of antigen-dependent proliferation of murine Th1 clones. In addition, we demonstrate that IL-10 inhibits splenic antigen-presenting cell (APC)-dependent proliferation of Th1 clones, at least in part, via down-regulation of APC-derived IL-12. Moreover, the failure of activated B cells to provide costimulation via IL-12 accounts for their inability to support optimal proliferative responses of Th1 clones. We also show that IL-12 regulates the ability of Th1 clones to respond to IL-4 and enhances their proliferation in response to IL-2, IL-7, or IL-15. In contrast, Th2 and Th0 clones appear refractory to the effects of IL-12, on antigen-dependent or growth factor-induced proliferation.