Immunosuppression induced by hepatic portal venous immunization spares reactivity in IL-4 producing T lymphocytes

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.

Interleukin-13, in combination with anti-interleukin-12, increases graft prolongation after portal venous immunization with cultured allogeneic bone marrow-derived dendritic cells

Portal venous (pv) transfusion before transplant with large numbers (100 x 10(6)) of irradiated multiple minor histoincompatible spleen cells (B10.Br) augments allogeneic skin graft survival in C3H mice. We have shown in earlier studies that this is correlated with preferential activation for production of type 2 cytokines (interleukin [IL]-4 and IL-10) and decreased production of type 1 cytokines (IL-2 and interferon [IFN] gamma). We have also shown that recombinant (r)IL-12, in association with anti-IL-10 monoclonal antibody, can reverse in vivo the graft prolongation afforded by pv immunization and the altered cytokine production that follows. Adoptive transfer of inhibition of graft rejection is possible at early times after pv immunization, using plastic adherent cells obtained from the liver of treated mice. We show below that within 4 days of pv immunization, dendritic cells (NLDC-145+) isolated from the thymus, mesenteric lymph node (MLN), and.

A role for gamma(delta)TCR+ cells in regulation of rejection of small intestinal allografts in rats

Lewis (LEW) rats received (Lewis x Brown Norway)F1 (LBNF1) small intestinal allografts (SIT) with graft venous drainage to either the portal vein (pv) or inferior vena cava (iv), along with immunization (pv or iv) with irradiated LBNF1 spleen cells. As reported earlier, in rats with pv drained grafts there was an increase in gammadeltaTCR+ cells infiltrating the Peyer's patches (PP) and mesenteric lymph node (MLN) compared with iv drained grafts. After restimulation in culture with irradiated LBNF1 spleen stimulator cells these PP and MLN cells from SIT rats with pv graft drainage were a prominent source of TGFbeta, IL-4, and IL-10. When subpopulations of cells from PP preparations were analyzed, an enriched (<2%betaTCR+) gammadeltaTCR+ population from SIT rats with pv graft drainage, but not iv drainage, was detected that suppressed in vitro type-1 cytokine production (IL-2, IFNgamma) from alphabetaTCR+ (<2%gammadeltaTCR+) cells derived from the MLN or peripheral lymph nodes (PLN) of these same animals. On adoptive transfer to naive LEW rats simultaneously receiving LBNF1 SIT, gammadeltaTCR+ enriched PP cells from these primary donors (pv immunized, SIT rats with pv graft drainage) produced prolonged graft/ animal survival compared with PP cells obtained from primary donors that had iv drained grafts. In addition, simultaneous infusion of anti-gammadeltaTCR monoclonal antibody into SIT rats with pv graft drainage blocked the graft enhancement normally seen in these animals. These data are consistent with an important role for type-2 cytokine producing gammadeltaTCR+ cells in the regulation of graft rejection in this model.

Correlation of peripheral blood lymphocyte and intragraft cytokine mRNA expression with rejection in orthotopic liver transplantation

BACKGROUND

Regulation of allograft rejection mediated by CD4+ T lymphocytes is dependent on the pattern of cytokines produced by these cells. The purpose of this study was to examine liver transplant recipients to determine whether peripheral blood lymphocyte (PBL), intragraft cytokine production, or both correlated with histologic assessment of graft rejection.

METHODS

PBL and liver biopsy specimens from transplant recipients were examined at varying times after transplantation. Biopsy samples were examined histologically. Messenger RNA was extracted from PBL and liver biopsy specimens and was then amplified by polymerase chain reaction with oligo-specific primer pairs for interleukin (IL)-2, IL-4, IL-6, transforming growth factor-beta, interferon-gamma, and beta-actin.

RESULTS

PBL transcription of IL-2, IL-6, and interferon-gamma was significantly increased in transplant recipients with rejection compared with that in recipients without rejection or healthy individuals who did not undergo transplantation (p < 0.05). Equivalent transcription of IL-4 and transforming growth factor-beta was observed in all patients regardless of rejection status. Graft specimens exhibited quantitative increases in IL-2 and interferon-gamma transcription during rejection with increased IL-4 transcription in the absence of rejection.

CONCLUSIONS

Our data show that specific patterns of peripheral and intragraft cytokine production play a role in the regulation of rejection in liver transplantation.

Prolongation of cardiac allograft survival by intraportal injection of donor antigens--differential mechanisms according to the timing of injection

Recently, we reported that intraportal (IP) injection of donor spleen cells (SPCs) before transplantation as well as at the time of transplantation significantly prolongs cardiac allograft survival in rats (7). Long-term establishment of chimerism induced by intraportal administration of SPCs could be a part of this prolongation. In this study, we examined the effect of irradiation of SPCs as a source of donor antigens on cardiac allograft survival. Experiments were carried out using DA (RT1a) as the donor and BUF (RT1b) as the recipient strain. Fifty million irradiated or nonirradiated SPCs were injected either intravenously (i.v.) or intraportally (i.p.) on day -10 or day 0, the day of cardiac allografting. Untreated animals rejected allografts within a mean survival time (MST) of 7.2 +/- 0.8 days (n = 5). Injection (i.p.) of SPCs on both day -10 (n = 4) and day 0 (n = 6) induced significant prolongation of MST over the control (19.0 +/- 4.7, 14.2 +/- 2.1 days; p < 0.001 vs. control), while i.v. injection of SPCs on either day -10 (n = 4) or day 0 (n = 4) failed to do so (9.2 +/- 1.0, 8.5 +/- 0.6 days). Significant prolongation was still observed when irradiated SPCs were injected on day -10 (n = 4; MST: 19.0 +/- 5.4 days, p < 0.002 vs. control), but not when injected on day 0 (n = 5; MST: 9.4 +/- 2.1 days). These data suggest that the immunosuppressive effect of i.p. injection of donor SPCs could be induced by differential mechanisms according to the timing of inoculation of donor antigens.

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.

A subset of gamma delta T-cell receptor-positive cells produce T-helper type-2 cytokines and regulate mouse skin graft rejection following portal venous pretransplant preimmunization

C3H/HeJ mice received B10.BR skin grafts following portal or lateral tail vein infusion of irradiated B10.BR spleen cells. Thereafter mice were injected with anti-alpha beta or anti-gamma delta T-cell receptor (TCR) monoclonal antibody (mAb). Anti-gamma delta TCR mAb abolished the increased graft survival afforded by portal venous (p.v.) immunization, and reversed the bias towards expression of mRNA for type-2 cytokines [interleukin-4 (IL-4), IL-10] seen in lymphoid tissue of p.v.-immunized mice. When gamma delta TCR+ and alpha beta TCR+ cells were isolated from the intestinal epithelial compartment (IEL), liver or Peyer's Patch (PP) of p.v.-immunized mice, the gamma delta TCR+ cells were found to be enriched in cells producing type-2 cytokines on rechallenge with irradiated B10.BR cells in vitro. gamma delta TCR+ cells from p.v.-immunized mice were further expanded in vitro with anti-CD3 and cytokines (combined IL-2 and IL-4). Following expansion these cells were capable of adoptively transferring increased B10.BR skin graft survival to naive mice, and continued to show a bias in type-2 cytokine synthesis after allostimulation in vitro. When gamma delta TCR chain expression was assessed in cells taken from p.v.-immunized mice, or in cells expanded in culture, our data suggest that p.v. immunization leads to oligoclonal, not polyclonal, expansion of those gamma delta TCR+ cells involved in inhibition of graft rejection.

Altered serum cytokines in hepatic and portal blood of rats at early times following portal venous infusion of semi-allogeneic cells

The liver of anaesthetized adult ( > 350 g) Lewis rats was perfused in vitro after cannulation of both the hepatic and portal vein, with clamping of the hepatic artery. Heparinized blood (400 microliters) was withdrawn at 0, 6, 12, 18, 24, 30 and 36 h from each site, and serum and peripheral blood lymphocytes (PBL) isolated after ficoll/hypaque separation. Serum was tested in bioassays for cytokines known to modulate lymphocyte:endothelial interactions in vivo and in vitro (IFN gamma, TGF beta, TNF alpha, IL-6, IL-1). In some experiments rats received, via portal venous infusion, a sterile inoculum of 150 x 10(6) semi-allogeneic (LBN F1) spleen cells immediately or 12 h after the start of the study. In animals which were unchallenged with cells via the portal vein, subtle differences in detectable cytokines were observed between hepatic and portal blood samples, as reported in earlier studies. Within 12 h the minor perturbations observed in cytokine profiles following surgical insult resolved, and the changes between hepatic and portal venous samples remained constant throughout the study in control rats. However, in rats treated with LBNF1 cells, changes in the cytokine profiles were seen compared with control animals, and as a function of time post F1 cell infusion. Changes in mRNAs for different cytokines were observed in PBL taken from portal/hepatic blood in these same animals. These data point to one possible mechanism whereby the liver may influence immunological processes following portal venous antigen challenge.

Manipulation of xenogeneic skin and/or renal graft survival in the rat-mouse concordant combination by portal vein pretransplant transfusion

We have examined whether portal venous pretransplant transfusion, which has been shown to produce prolongation of rodent vascularized (small intestine, kidney) and nonvascularized (skin) allografts, in the absence of other nonspecific immunosuppression, can produce similar graft prolongation in animals receiving vascularized or nonvascularized xeno- (not allo-) grafts. Rat kidney or skin grafts were transplanted into mice after portal venous pretreatment with rat or mouse spleen cells. Animals in some groups received additional immunosuppressive regimens including drug therapy (methotrexate, cyclosporin A) or monoclonal antibody treatment (anti-CD4, anti-CD8). Animal survival and serum creatinine was followed daily, and lymphoproliferation, cytokine production (including cytokine mRNA in grafted mice) and anti-xenograft antibody production was measured at distinct time points postgrafting. Both portal venous pretransplant transfusion and anti-CD4 monoclonal antibody treatment led to increased graft survival. However, unlike the rodent allograft model, graft survival in these animals was not simply explained by altered Th1/Th2 ratios. Other mechanism(s), possibly including xenoantibody production, are likely of importance in the regulation of xenograft rejection.

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)

Functional activity in host and graft lymphoid tissue of rats receiving syngeneic heterotopic small bowel transplants with portal or systemic drainage

Adult Lewis rats received syngeneic accessory small bowel transplants (SBT) with venous drainage to the portal vein (PV) or the inferior vena cava (IVC)/hetero-portal (HP) or hetero-systemic (HS) grafts, respectively. At varying times thereafter (5-300 days post-transplantation) animals were killed and cells from different lymphoid organs were tested in vitro for their generation of lymphoproliferative and cytotoxic T-cell responses, as well as their ability to produce a variety of lymphokines after alloantigen or mitogen stimulation. Despite marked decreases in cell recovery in Peyer's Patches of HS rats, no significant loss of cell function (on a per cell basis) was noted in any animal group. Total recovered activity per organ was decreased in small intestinal tissue (host and graft) of HS recipients regardless of the assay under study.

Age-related changes in interleukin production in BALB/cNNia and SJL/J mice and their modification after administration of foreign macromolecules

In vitro production of Interleukin-2, -3, -4 and -10 by activated lymphocytes of BALB/cNNia and SJL/J was studied. While IL-2 production in BALB/c mice remains constant throughout the life span of the animals (8-113 weeks), an increase in production from stimulated SJL cells was seen. Age-related increases in IL-3 and IL-4 production occur between young and middle age (8-60 weeks) in both strains. Some organ differences in quantity of lymphokine produced were seen; the direction of age-related changes was the same for lymphocytes of spleen and MLN. The exceptional feature of BALB/cNNia was the relative stabilization of the levels of interleukin production, as animals approach old age. BALB/cNNia and SJL, which are at the two opposite extremes of lifespan, differ also in their response to molecular interventions: in BALB/cNNia fetal sheep liver extract and hemocyanin increase the output of interleukins. This is in striking contrast to the effects observed in older SJL mice in which the extract reduced the output of IL-3 and IL-4 by old animals, whereas hemocyanin increased the output of IL-2 and IL-3 at all ages tested.

Cytokines as mediators of organ graft rejection and tolerance

The analysis of cytokines following organ transplantation continues to flourish as a major area of investigation for transplant biologists. Over the past year many papers have reported the use of both molecular and antibody-based tools to dissect the expression of cytokines during graft rejection in both experimental and clinical transplantation. Further, how the expression of cytokines is altered during the induction of tolerance has been investigated by several groups.

Migration patterns of lymphocytes following syngeneic heterotopic small bowel transplantation in rodents

Adult rats received syngeneic accessory small bowel grafts with venous drainage to either the portal vein (hetero-portal) or the inferior vena cava (hetero-systemic). Lymphoid cell recovery in different lymphoid organs (spleen, pooled peripheral lymph nodes, mesenteric nodes, Peyer's Patches) was evaluated at varying times (days 0-300) post-grafting. While minimal changes were observed for cell recovery in other organ tissues, lymphocyte recovery in Peyer's Patches of both host and graft small intestine of hetero-systemic animals was decreased from 10- to 100-fold with respect to hetero-portal recipients or non-operated controls. These changes were seen throughout the time course of the study. In additional experiments, lymphoid cells from different organs/donors were labelled in vitro with 111In and injected intravenously into normal/transplanted recipients. Recovery of 111In in various organs was assessed at 1 and 6 h postinjection. The major change seen was in the decreased ability of mononuclear cells derived from Peyer's Patches to migrate to small intestinal tissue (host and graft) in hetero-systemic recipients. In addition, Peyer's Patch cells from these animals 'homed' poorly to small intestine in non-operated animals by comparison with cells from normal rats (or hetero-portal donors).

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

Pretransplant transfusion of multiple minor histoincompatible spleen cells to naive recipient mice by the portal vein suppresses the ability of those animals to reject skin grafts from mice syngeneic with those used for transfusion, and decreases in vitro immunity on rechallenge with the same antigens, by comparison with mice receiving transfusion by the lateral tail vein. We have shown elsewhere that this is correlated with a diminished activation of Th1 cells for IL-2 production, without apparently affecting activation of Th2 cells for IL-4 production. Similar data are obtained by merely infusing hepatic (vs. splenic) antigen-presenting cells (APC) into normal mice, or by challenging immune cells in vitro with antigen-pulsed hepatic (vs. splenic) APC. However, when antigen-pulsed splenic APC are incubated with immune T cells in the presence of anti-LFA-1 monoclonal antibody (Mab), selective activation of Th2 cells (as is seen with hepatic APC) again occurs at the expense of activation of Th1 cells. Anti-LFA-1 Mab causes little perturbation in lymphokine production from T cells stimulated with hepatic APC. Using cDNA probes for IL-2 and IL-4 we show that T-cell activation in the presence of anti-LFA-1 Mab leads to selective inhibition of transcription of IL-2 mRNA.