Antigen presentation by murine splenic, but not hepatic, antigen-presenting cells to induce IL-2/IL-4 production from immune T cells is regulated by interactions between LFA-1/ICAM-1

Evidence That an OX-2-Positive Cell Can Inhibit the Stimulation of Type 1 Cytokine Production by Bone Marrow-Derived B7-1 (and B7-2)-Positive Dendritic Cells

We reported that hepatic mononuclear, nonparenchymal cells (NPC) can inhibit the immune response seen when allogeneic C57BL/6 dendritic cells (DC) are incubated with C3H spleen responder cells. Cells derived from these cultures transfer increased survival of C57BL/6 renal allografts in C3H mice. We also found that increased expression of OX-2 on DC was associated with inhibition of cytokine production and renal allograft rejection. We explored whether inhibition by hepatic NPC was a function of OX-2 expression by these cells. Fresh C57BL/6 spleen-derived DC were cultured with C3H spleen responder cells and other putative coregulatory cells. The latter were derived from fresh C3H or C57BL/6 liver NPC, or from C3H or C57BL/6 mice treated for 10 days by i.v. infusion of human Flt3 ligand. Different populations of murine bone marrow-derived DC from cultures of bone marrow with IL-4 plus granulocyte-macrophage-CSF were also used as a source of putative regulator cells. Supernatants of all stimulated cultures were examined for functional expression of different cytokines (IL-2, IL-4, IFN-γ, and TGFβ). We found that fresh C57BL/6 splenic DC induced IL-2, not IL-4, production. Cells from the sources indicated inhibited IL-2 and IFN-γ production and promoted IL-4 and TGFβ production. Inhibition was associated with increased expression of OX-2 on these cells, as defined by semiquantitative PCR and FACS analysis. By size fractionation, cells expressing OX-2 were a subpopulation of NLDC145+ cells. Our data imply a role for cells expressing OX-2 in the regulation of induction of cytokine production by conventional allostimulatory DC.

TCR diversity in gammadeltaTCR+ hybridomas derived from mice given portal vein donor-specific pre-immunization and skin allografts

Portal venous (p.v.) immunization with multiple minor histoincompatible cells leads to antigen-specific increased skin allograft survival. GammadeltaTCR+ hybridoma cells, prepared from mesenteric lymphocytes of p.v. immunized animals, can adoptively transfer this increased graft survival to naive animals. We have analyzed VgammaVdelta gene usage, and TCR gamma-chain junctional diversity in gammadeltaTCR+ hybridomas from mice immunized with different antigen combinations by p.v. or conventional lateral tail vein (i.v.) immunization. Following p.v. immunization two independent sets of hybridoma cells were derived, one expressing a common gamma-chain junctional sequence which was also found in > 85% of the hybridomas derived following i.v. immunization, while the other set showed remarkable gamma-chain junctional sequence diversity. The diversity seen in these latter hybridomas was associated with the antigen specificity of the hybridoma cells. Cells expressing these 'unique' TCR junctional sequences were stimulated to produce cytokines both by hsp and by minor-histocompatibility-specific irradiated peritoneal cells. Cells expressing TCR with a common gamma-chain junctional sequence were stimulated to cytokine production by MHC-matched but minor-histocompatibility mismatched (as well as matched) peritoneal cells, but not by hsp. We suggest that p.v. immunization results in stimulation of both antigen-specific and non-specific regulatory gammadeltaTCR+ cells, which can be distinguished by gamma-chain TCR sequence diversity.

Donor-specific stimulation of peripheral blood mononuclear cells from recipients of orthotopic liver transplants is associated, in the absence of rejection, with type-2 cytokine production

In this study, we examined the cytokine production by human peripheral blood mononuclear cells (PBM) from recipients of orthotopic liver transplants which had been stimulated by donor-specific alloantigen. Levels of interleukin (IL)-2, IL-4, interferon (IFN)-gamma, IL-10 and transforming growth factor (TGF)-beta produced in vitro from PBM of 15 transplant recipients at 5-7 months post transplantation were analysed after donor-specific, third-party, or non-specific stimulation. Mononuclear cell proliferation in response to stimulation and cytokine mRNA from the cell cultures were assayed. Donor-specific antigen was obtained from donor spleen cells which had been obtained and frozen in liquid nitrogen at the time of organ retrieval. Third-party restimulation used equivalent numbers of spleen cells pooled from the other 14 organ donors. Cytokine production was correlated with the clinical condition of the patient, including biopsy results when available, and biochemical data. The data show a highly significant correlation between the donor-specific- and third-party- stimulated IL-4 and IL-10 production from recipient PBM with stable liver graft function as assessed by histopathology and/or biochemistry. This correlation was independent of level of immunosuppression. These data strongly support a role for IL-4 and/or IL-10 in the induction and/or maintenance of tolerance to human liver allografts. Measurement of the levels of these cytokines from recipient PBM after donor-specific antigen stimulation in vitro may be a useful test for monitoring for acute allograft rejection.

A role for persisting antigen, antigen presentation, and ICAM-1 in increased renal graft survival after oral or portal vein donor-specific immunization

BACKGROUND

We studied the mechanism behind increased renal allotransplant survival when C3H mice received donor-specific portal vein or oral immunization with C57BL/6 cells. Both regimens lead to donor-specific increased graft survival, in association with decreased production of cytotoxic T lymphocytes and altered cytokine production from host lymphocytes (decreased interleukin [IL]-2 production; increased IL-4, IL-10, and transforming growth factor-beta).

METHODS

We examined a role for persistent donor-derived antigen, in association with host dendritic cells, as well as a role for intercellular adhesion molecule-1 (ICAM-1), in the maintenance of unresponsiveness in host C3H spleen cells to donor antigen. We investigated whether there was a cooperative interaction between donor dendritic cells (DC) and host hepatic mononuclear cells in the induction of immunoregulation in C3H cells.

RESULTS

In mice with surviving renal grafts, donor antigen, in association with host DC, induced the recall of cytotoxicity from C57BL/6 immune C3H spleen cells and IL-4 but not IL-2 production, despite the decreased cytotoxicity seen in the renal transplant recipients themselves. Fresh donor DC induced IL-2 but not IL-4 production. Blocking expression of ICAM-1 on donor grafts, either with anti-ICAM-1 monoclonal antibodies after renal grafting or using grafts from ICAM-1 "knockout" mice, led to further increased survival. Cultured C3H responder spleen cells, incubated with C57BL/6 DC and C3H hepatic cells, transferred hyporesponsiveness to C57BL/6 cells in vitro and in vivo (as assayed by survival of C57BL/6 renal allografts).

CONCLUSIONS

Our data suggest a role for ICAM-1, persistent donor antigen (on host DC), and accessory hepatic monocytes in the induction and maintenance of tolerance after portal vein immunization.

The effect of immunomodulation of stimulator antigen presenting cells on subsequent responder T-cell function

In this study, we examined whether lipopolysaccharide (LPS)-, interferon-gamma (IFN-gamma) or 16,16-dimethyl prostaglandin E2 (dmPGE2)-pretreatment of stimulator spleen cells from C57BL6 (B6) mice affects effector function of responder T-lymphocyte from C3H/HeJ mice. Stimulation of B6-derived splenic mononuclear cells (SMNCs) with LPS (10 micrograms/ml) prior to their utilization as stimulator cells in a mixed lymphocyte culture (MLC) resulted in an increase in responder T-lymphocyte proliferation compared to utilization of unstimulated SMNC (P < 0.05). IFN-gamma demonstrated similar effects in a dose dependent fashion with maximal stimulatory effect seen at 1000 U/ml. In contrast, pretreatment of stimulator SMNC with dmPGE2 resulted in dose-dependent inhibition of the responder T-lymphocyte proliferation with maximum inhibitory effect seen using a concentration of dmPGE2 of 10(-5) M. The presence of indomethacin in the MLC did not reverse this effect. These data demonstrate the effect of immunomodulation of stimulator spleen cells on subsequent T-lymphocyte function.

Graft-infiltrating cells in rats receiving orthotopic semiallogeneic small intestine transplantation with portal or systemic venous drainage

The effect of alterations in venous drainage, from either ivc to portal vein (pv), along with peritransplant systemic (ivc) or portal (pv) venous alloimmunization with irradiated semiallogenic cells, on cell subset recovery in lymphoid organs of Lewis rats receiving orthoptic small bowel allografts (from LewisXBrown Norway) F1, LBNF1) was examined. Combined portal, venous drainage and alloimmunization has been reported to increase graft/recipient survival in this model. FACS analysis using monoclonal antibodies specific for different lymphocyte subsets was performed on cell suspensions of peripheral (P) and mesenteric (M) lymph node (LN), small bowel intraepithelial lymphocytes (SBIEL), and Peyer's patch (PP) lymphocytes on days 2 and 8 posttransplantation. Donor cell contributions to these cellular analyses were estimated by comparison of FACS staining with polyclonal anti-Lewis or Lewis anti-LBNF1 antibodies. Control animals received syngeneic grafts. In both syngeneic and semi-allogenic transplants with pv or ivc drainage there was no consistent difference in cell subsets from in PLN compared with those of control nongrafted rats. Approximately 50% to 60% of these cells were alphabetaTcR+ with a CD4+/CD8+ ratio of 3-4:1 and a (CD4++CD8+)/alphabetaTcR+ ratio of 1:1. Some 5% to 12% ED3+ cells were also present. In IEL, MLN, and PP by contrast, there were significant differences in cells recovered from rats with ivc vs. pv drainage of grafts. The most striking changes reflected a decreased CD4+/CD8+ and alphabetaTcR+gammadeltaTcR+ cells in these tissues in rats predestined to show prolongation of allograft survival (ivc vs. pv injected IEL CD4/CD8+ ratios and alphabetaTcR+gammadeltaTcR+ ratios 1.0, 0.7 and 5.0, 1.0, respectively. These data are consistent with a proposed role for such gammadeltaTcR+ cells in the local regulation of graft rejection.

The role of ICAM-1 in the induction of antigen-specific T cell hyporesponsiveness

We have previously demonstrated that pre-transplant transfusion of allogeneic splenic mononuclear cells from B10.BR mice to C3H/HeJ recipient mice resulted in subsequent antigen specific skin graft prolongation and an associated predominance of IL-4-producing T lymphocytes. In this report, we examined the role of ICAM-1 in the induction of T cell hyporesponsiveness and skin graft prolongation following intrahepatic alloantigen delivery. C3H/HeJ mice receiving splenic cells from B10.BR mice intrahepatically showed antigen-specific enhanced skin graft survival. This graft survival was further prolonged following pre-treatment of infused cells with anti-ICAM-1. No such prolongation was seen following intravenous administration of cells in the presence or absence of anti-ICAM-1 pre-treatment. Anti-ICAM-1 infusion alone similarly had no effect when given intrahepatically or peripherally. T lymphocytes from the mice receiving intrahepatic splenic cells and anti-ICAM-1 produced significantly higher amounts of IL-4 compared to mice receiving intrahepatic cells alone or intravenous cells. PCR analysis of ICAM-1 mRNA transcripts demonstrated an increased expression of ICAM-1 in the spleen compared to the liver. These results suggest that ICAM-1 plays an important role in the induction of T cell hyporesponsiveness and allograft prolongation following the intrahepatic encounter of alloantigen.

Altered patterns of migration of cytokine-producing T lymphocytes in skin-grafted naive or immune mice following in vivo administration of anti-VCAM-1 or -ICAM-1

Naive or preimmunized (to B10.BR or BALB.k) C3H/HeJ mice received skin grafts from multiple minor histoincompatible B10.BR or BALB.k mice following antigen-specific portal venous (p.v.) pretransplant transfusion, a protocol known to produce prolongation of graft survival in naive animals. In addition, groups of mice received intravenous (i.v.) infusion following transplantation with a mixture of monoclonal antibodies (mAb) to vascular adhesion molecule-1L: very late activation antigen-4 (VCAM-1:VLA-4) or intracellular adhesion molecule-1:lymphocyte function-associated antigen-3 (ICAM-1:LFA-1). Cells were harvested from different tissues of the grafted mice at various times post grafting. RNA was extracted and analysed, using polymerase chain reaction, for expression of different cytokines potentially involved in the regulation of graft rejection [interleukin-2 (IL-2), IL-4, IL-6, IL-10, tumour necrosis factor-alpha, interferon-gamma and transforming growth factor-beta]. In addition, using limiting dilution analysis, we investigated the frequency of allo-specific and third-party reactive cells producing IL-2 and IL-4 in vitro in different tissues of grafted mice following these treatments. The mAb treatment protocol which produced optimum increases in graft survival in naive versus immune mice was different, with anti-LFA-1:ICAM-1 superior for naive mice compared with anti-VLA-4:VCAM-1, and vice versa for immune animals. However, in each case, increased survival was associated with increases local to the graft in the frequency of occurrence of antigen-specific type-2 cytokine-producing cells.

Manipulation of skin graft rejection in alloimmune mice by anti-VCAM-1:VLA-4 but not anti-ICAM-1:LFA-1 monoclonal antibodies

C3H mice were immunized by repeated skin grafting with B10.BR tail skin. Ten days after the last immunization mice received 100 micrograms (intravenously) of a variety of different monoclonal antibodies (mAbs: anti-ICAM-1, -LFA-1, -VCAM-1, -VLA-4), alone or in combination, followed by further B10.BR skin grafts. Control animals received injections of saline only. Skin graft survival was monitored daily in all groups. Further injections of antibody were given every second day until graft rejection occurred. In separate studies lymphoid cells were harvested from various tissues of the grafted mice at 6 and 20 days post grafting. Aliquots of each sample were analysed by polymerase chain reaction for mRNA for different cytokines (interleukins IL-2, IL-4, IL-10 and IFN gamma (gamma-interferon)) believed to be important in the regulation of graft rejection. In addition, lymphoid cells were restimulated in vitro with irradiated B10.BR or third-party stimulator cells in the presence or absence of monolayers of C3H-derived endothelial cells (EC), in an attempt to mimic the in vivo environment of the interactions of cells engaged in alloreactivity in these mice. Only anti-VCAM-1 caused significant prolongation of graft survival in immune mice, while in contrast only the combination of anti-ICAM-1 and anti-LFA-1 produced enhanced survival in naive animals. In each case increased survival was associated with decreased activation of Th1 cells (diminished IL-2, IFN gamma) and increased activation of Th2 cells (increased IL-4, IL-10).(ABSTRACT TRUNCATED AT 250 WORDS)

Regulation of IFN-gamma and IL-10 synthesis in vivo, as well as continuous antigen exposure, is associated with tolerance to murine skin allografts

C3H/HEJ mice are rendered hyporesponsive to multiple minor incompatible (B10.BR) skin allografts by pretreatment with irradiated B10.BR lymphoid cells injected via the portal vein, but not the lateral tail vein. As assessed by PCR with lymphocytes taken from grafted mice, or by measuring cytokines in vitro from antigen-restimulated cells, this hyporesponsiveness is associated with decreased mRNA for IFN-gamma and IL-2 production, but enhanced mRNA for IL-4 and IL-10 production. In mice given B10.BR cells via the tail vein, but in addition injected every second day with anti-IFN-gamma antibody, similar enhanced graft survival (with diminished IFN-gamma/IL-2 and enhanced IL-4/IL-10 production) was seen. In a separate study spleen cells from pretreated mice were "parked" in lethally irradiated syngeneic mice for 21 days, along with B10.BR skin grafts to some of the recipients. Only when recipients received this reexposure to B10.BR antigen did adoptively transferred spleen cells show "persistence" of the ability to produce delayed graft rejection and preferential IL-4 production in vitro.