Ethylenecarbodiimide-treated splenocytes carrying male CD4 epitopes confer histocompatibility 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-gamma, 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.

Ethanol consumption modifies dendritic cell antigen presentation in mice.

BACKGROUND: Alcohol consumption impairs type 1 cell-mediated adaptive immune responses both in vivo and in vitro. The present study investigated the effect of alcohol consumption on antigen-presenting cell (APC) populations and cytokine production. METHODS: BALB/c were fed ethanol-containing, pair-fed isocaloric liquid control, or solid diets for 11 days. Macrophage and dendritic cell (DC) populations were isolated by paramagenetic bead separation and used to present ovalbumin (OVA) to highly purified syngeneic CD4+ T cells derived from DO11.10 T cell receptor transgenic mice in coculture. DC isolated from diet-fed mice were also used to present OVA to highly purified CD4+ T cells derived from antigen-naïve DO11.10Rag2-/- mice that are devoid of memory T cells. In vitro cytokine responses, interleukin (IL) -2, IL-6, IL-12, IL-13, IL-17A, and interferon-gamma (IFN-gamma) were measured by enzyme-linked immunosorbent assay. Flow cytometry measured cell surface molecule expression. RESULTS: Alcohol consumption impairs delayed hypersensitivity responses (type 1) and enhances serum IgE levels (type 2). CD11c+ DC, but not F4/80+ macrophages, support cytokine responses by purified CD4+ T cells. CD11c+ DC derived from ethanol consuming BALB/c mice show diminished ability to support IFN-gamma responses by purified CD4+ T cells derived from DO11.10 or DO11.10Rag2-/- mice. Subset analysis indicates that of the 3 "conventional" DC subsets found in mouse spleens, CD11c+CD8(alpha)+ DCs are both responsible for OVA presentation and susceptible to the effects of ethanol. Ethanol consumption does not overtly alter the percent of splenic DC, but does increase the surface density of CD11c on these cells. Data show that cocultures containing purified CD4+ T DO11.10 cells and APC derived from alcohol-consuming mice show decreased IL-6, IL-12, IL-17A, and IFN-gamma and increased IL-13 cytokine production in response to OVA stimulation. CONCLUSIONS: Ethanol alters CD11c+CD8(alpha)+ DC function, affecting cytokines responsible for adaptive immune responses. A unifying hypothesis for the underlying mechanism(s) of ethanol's effect upon adaptive immune function is proposed.

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.

Restoration of ethanol-compromised T(h)1 responses by sodium orthovanadate.

Alcohol consumption often diminishes antigen-specific cell-mediated immunity. In alcohol-consuming mice IFN-gamma and delayed-type hypersensitivity (DTH) responses are blunted, although antigen-specific T cell proliferation and IL-2 responses are largely unaffected, suggesting that alcohol differentially affects signal transduction pathways. In the present report we explore the use of the phosphatase inhibitor, Na3 VO4 to restore IFN-gamma secretion in the presence of ethanol both in vivo and in vitro. We show that Na3 VO4 restores IFN-gamma in vitro and antigen-specific DTH in vivo to the levels seen in alcohol non-consuming mice. Our data support the contention that ethanol, by up-regulating phosphotyrosine phosphatase, diminishes the IFN-gamma signal transduction pathway.

Differential effects of T-cell activation on gastric and small bowel permeability in alcohol-consuming mice.

BACKGROUND: A number of variables influence the effect(s) of alcohol on distinct segments of the intestine. In these studies, we examined the effect of T-cell activation on gastric and small bowel permeability in alcohol-fed mice. METHODS: Gastric permeability was assessed using sucrose absorption, whereas small bowel permeability was followed using the ratio of lactulose to mannitol absorption and inulin absorption. T cells were activated by injecting antigen OVA(323-339) into DO11.10 T-cell receptor transgenic mice. RESULTS: T-cell activation increased gastric and small bowel permeability through a pathway mediated by interferon-gamma and tumor necrosis factor. In mice that were fed a liquid diet that contained 30% ethanol-derived calories for 2 weeks, T-cell activation increased gastric permeability to levels greater than that observed in solid diet or pair-fed, liquid control diet. By comparison, changes in small bowel permeability induced by T-cell activation were abrogated in alcohol-fed mice. Analysis of intestinal cytokine mRNA levels (interferon-gamma and tumor necrosis factor) indicated that relevant mucosal T-cell function was preserved in alcohol-fed mice. CONCLUSIONS: Overall, these data suggest that alcohol potentiates the effects of T-cell activation on gastric permeability, at the same time blunting effects on small bowel permeability

Alcohol-mediated polarization of type 1 and type 2 immune responses.

Immune responses of alcoholics are often compromised, placing them at increased risk for frequent and severe infections. We demonstrate, using a murine model that parallels human alcoholism, that ethanol consumption polarizes adaptive immune responses by CD4+ T helper lymphocytes (Th). Alcohol impairs Th1-regulated cell-mediated, although Th2-regulated humoral responses are largely unimpaired and may be enhanced. Ethanol's effect is most pronounced during the early or cognitive phase of the immune response, when antigen-presenting cells (APC) interact with T cells. We find that alcohol does not act directly upon T cells, but upon APC. Consequences of this interaction of alcohol with APC in vivo are diminished Th1-mediated delayed hypersensitivity (DTH) reactions, while at the same time increased Th2-regulated serum IgE levels are seen. Further ethanol consumption leads to decrease affinity of the IgG2a and IgG2b Th1-regulated antibody isotypes.