Carl Waltenbaugh

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

Abstract Intracerebral inoculation of Theilers 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.

Antigen-specific responses accelerate bacterial clearance in the bladder.

Urinary tract infections (UTIs) cause patient morbidity and have a substantial economic impact. Half of all women will suffer a UTI at least once, and 25% of these women will have recurrent infections. That 75% of previously infected women do not become reinfected strongly suggests a role for an adaptive immune response. The goal of this study was to characterize the adaptive immune responses to uropathogenic Escherichia coli (UPEC), the predominant uropathogen. A novel murine model of UTI reinfection was developed using the prototypic cystitis UPEC isolate NU14 harboring a plasmid encoding OVA as a unique antigenic marker. Bacterial colonization of the bladder was quantified following one or more infections with NU14-OVA. Animals developed anti-OVA serum IgG and IgM titers after the initial infection and marked up-regulation of activation markers on splenic T cells. We observed a 95% reduction in bacterial colonization upon reinfection, and splenic leukocytes showed Ag-specific proliferation in vitro. Adoptive transfer of splenic T cells or passive transfer of serum from previously infected mice protected naive syngeneic mice from UPEC colonization. These findings support our hypothesis that adaptive immune responses to UPEC protect the bladder from reinfection and form the basis of understanding susceptibility to recurrent UTI in women.

Alcohol Consumption Alters Antigen‐Specific Th1 Responses: Mechanisms of Deficit and Repair

Among the physiological effects associated with excessive alcohol consumption are alterations in immune function. Alcohol impairs T-helper 1 lymphocyte (Th1) regulated, cell-mediated immune responses. Antibody responses, regulated by T-helper 2 lymphocyte (Th2), are either unimpaired or enhanced. Antigen presenting cells are central to the development of both Th1 and Th2 regulated immune responses. We used both T-cell receptor transgenic and conventionally immunized mice to demonstrate that ethanol consumption directly affects antigen presenting cells that, in turn, determines whether Th1 or Th2 response patterns predominate. Ethanol consumption inhibits Th1-associated interleukin-12 and interferon-gamma cytokine production and delayed-type hypersensitivity. Administration of exogenous recombinant interleukin-12 both restores interferon-gamma levels and delayed-type hypersensitivity responses in ethanol-consuming mice.

Ethanol impairs the induction of delayed hypersensitivity in C57BL/6 mice

Excessive alcohol consumption impairs T-cell-dependent immune function. Whether this impairment results from the direct inhibition of helper T (Th) cells or from inhibition of the cells that process and present antigen to Th cells is unclear. The present study examines the temporal effect of dietary alcohol on the development of delayed hypersensitivity (DTH) in C57BL/6 mice. We find that ethanol consumption just prior to and during the cognitive phase of the immune response impairs the development of a DTH response. Ethanol consumption initiated after the cognitive phase and during the effector phase of the immune response has no significant effect upon the elicitation of a DTH response. The results suggest that significant ethanol-induced impairment of DTH responses occurs during the cognitive phase of the immune response, when antigen presentation and recognition occur.

Impaired antigen presention by splenocytes of ethanol-consuming C57BL/6 mice

Abstract Excessive alcohol consumption impairs T-cell-dependent immune function. Whether this impairment results from the direct inhibition of helper T (Th) cells or from inhibition of the cells that process and present antigen to Th cells is unclear. The present study examines the effect of dietary alcohol on the ability of spleen cells from C57BL/6 mice to present antigen to T-cell hybridomas. We find that ethanol consumption impairs the ability of spleen cells to present hen egg lysozyme (HEL) in vitro. This impairment was seen for native HEL protein, a hapten-modified HEL, and a peptide bearing a minimal T-cell epitope (HEL 51–60) that requires no additional enzymatic processing. These results suggest that deficiencies in immune responsiveness in alcohol-consuming individuals may include antigen presentation.

Fatty acid ethyl ester synthesis by the isolated perfused rat heart

Fatty acid ethyl esters (FAEEs), nonoxidative by-products of ethanol metabolism, are found in various tissues and plasma after ethanol ingestion and may be responsible for some of the pathological changes observed in alcohol-consuming individuals. Previous studies demonstrated that several different enzymes, including lipoprotein lipase (LPL), can catalyze FAEE synthesis in vitro. We report that LPL catalyzes FAEE synthesis in isolated rat hearts perfused with chylomicrons in the presence of ethanol. Most of the FAEEs accumulated in the perfusate, suggesting that in vivo, plasma FAEEs derive from LPL-mediated synthesis. Our results are the first demonstration of the direct involvement of a specific enzyme, LPL, in FAEE synthesis under physiological conditions.

Ethylenecarbodiimide-Treated Splenocytes Carrying Male CD4 Epitopes Confer Histocompatability Y Chromosome Antigen Transplant Protection by Inhibiting CD154 Upregulation

In humans and certain strains of laboratory mice, male tissue is recognized as nonself and destroyed by the female immune system via recognition of histocompatibility Y chromosome Ag (Hya). Male tissue destruction is thought to be accomplished by CTLs in a helper-dependent manner. We show that graft protection induced with the immunodominant Hya-encoded CD4 epitope (Dby) attached to female splenic leukocytes (Dby-SPs) with the chemical cross-linker ethylenecarbodiimide significantly, and often indefinitely, prolongs the survival of male skin graft transplants in an Ag-specific manner. In contrast, treatments with the Hya CD8 epitopes (Uty-/Smcy-SPs) failed to prolong graft survival. Dby-SP–tolerized CD4+ T cells fail to proliferate, secrete IFN-γ, or effectively prime a CD8 response in recipients of male grafts. Ag-coupled splenocyte treatment is associated with defective CD40–CD40L interactions as demonstrated by the observation that CD4 cells from treated animals exhibit a defect in CD40L upregulation following in vitro Ag challenge. Furthermore, treatment with an agonistic anti-CD40 Ab at the time of transplantation abrogates protection from graft rejection. Interestingly, anti-CD40 treatment completely restores the function of Dby-specific CD4 cells but not Uty- or Smcy-specific CD8 cells.

Cell-mediated immune responses to poliovirus. I: Conditions for induction, characterization of effector cells, and cross-reactivity between serotypes for delayed hypersensitivity and T cell proliferative responses

Human polioviruses are categorized into three distinct serotypes (types 1, 2, and 3) based upon their reactivity with specific antibodies. Although a great deal of information has been amassed about the induction and characterization of poliovirus antibody responses, little is known about cell-mediated immunity to poliovirus and its role in protection. Here, we show that intracutaneous injection of ultraviolet light-inactivated poliovirus into the tailbase of BALB/c mice induces delayed hypersensitivity (DTH) and T-cell proliferative (Tprlf) responses. Both DTH and Tprlf responses to poliovirus are mediated by Ly-1high2-, L3T4-bearing T cells. Moreover, known serologic cross-reactivity (i.e., antibody-mediated) of poliovirus serotypes is not predictive of cross-reactivity between the cell-mediated immune responses.

Mechanisms of genetic control of immune responses. I: Evidence for distinct multi-step helper T-cell pathways in cellular and humoral responses to GAT

We examined multiple genetically regulated Immoral and cell-mediated immune (CMI) responses to poly(glu60ala30tyr10) (GAT) using a panel of mouse strains. We show that assignment of responder/nonresponder status depends upon the assay method. In addition, two distinct categories of nonresponder mice were found: (1) those which are unresponsive by all parameters tested (H-2q and H-2s haplotypes) and (2) those which are partially nonresponsive [H-2bm12 mutant strain—a low/nonresponder by splenic plaque-forming cell (PFC) and delayed-type hypersensitivity (DTH) responses, but exhibits B6 parental levels of high GAT-specific T-cell proliferation (Tprlf) and interleukin-2 production]. The distinction between these two nonresponder types was confirmed by complementation tests in which significant GAT-specific PFC and DTH responses were seen in (H-2q × H-2bm12)F1 hybrids, but not in (H-2q × H-2s)F1 hybrids. Suppressor T cells (Ts) also play a selective role in nonresponsiveness to GAT. Cyclophosphamide treatment of nonresponders (to eliminate Ts activity) as well as immunization with GAT coupled to the immunogenic carrier MBSA result in the development of GAT-specific humoral, but not CMI responses. Our results indicate that the T cell is the cellular site of Ir gene expression and that Tprlf responses do not correlate with functional helper T-cell activity and suggest distinct, multi-step Th/Ts regulatory pathways in the development of humoral and CMI effector functions.

A rapid method for quantitation of antiviral antibodies

This paper examines the parameters necessary for the efficient measurement of anti-Theilers murine encephalomyelitis virus (TMEV) antibodies in an affinity-dependent manner using a variation of a solid-phase particle concentration fluorescence immunoassay (PCFIA). By allowing antibody to react with fluorochrome-labelled virus in fluid phase and subsequently capturing the resulting virus-antibody complexes with anti-immunoglobulin coated polystyrene particles (fluid-phase PCFIA), the present assay allows for both greater sensitivity, specificity and preservation of conformational viral epitopes than do solid-phase immunoassays. Fluid-phase PCFIA proved to be a more rapid quantitative assay than ELISA and significantly diminished non-specific binding by both untreated and heat-inactivated normal mouse sera. This methodology also allowed us to perform competition assays and to determine the dissociation kinetics of anti-viral antibody preparations, investigations which cannot generally be performed as solid-phase immunoassays. Thus fluid-phase PCFIA is a rapid and efficient immunoassay with excellent reproducibility and great versatility.