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.

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).

Prolonged lung allograft survival with a short course of FK 506

We examined the hypothesis that FK 506 would induce graft acceptance after lung transplantation. Left lung allotransplantation was performed in size-matched mongrel dogs allocated to control (no immunosuppression, n = 3) and FK 506 (n = 5) groups. FK 506 (1.2 mg/kg intramuscularly every day) was given on posttransplantation days 0, 1, and 2. No other immunosuppressive agents were administered to either group. Chest x-ray and transplant lung physiologic assessments were performed on the fifth day and weekly thereafter. On day 29 an open lung biopsy and a third-party skin graft were performed. Lymphocytes were harvested and frozen from the recipient peripheral blood before transplantation and on days 8 and 29 afterwards for assessment in mixed lymphocyte reaction. Dogs were killed when their chest x-ray films showed allograft opacification or when the skin graft was rejected. Control lungs were all rejected after a median of 5 days. In the FK 506 group, one of five dogs aspirated during the fifteenth-day assessment and was killed, on the twenty-ninth day, because of severe rejection. At day 29, in the other four dogs, the transplanted lung yielded an arterial oxygen tension of 613 +/- 25 mm Hg (mean +/- standard deviation) and lung biopsy specimens showed no abnormalities histologically. These four dogs rejected third-party skin grafts after a median of 10 days. In two FK 506 dogs, mixed lymphocyte reaction at day 8 showed suppression of proliferation responses against donor and third-party lymphocytes. By day 29 responses against third-party lymphocytes had returned to almost preoperative levels, whereas antidonor responses were still suppressed. After skin graft rejection and killing, one of four dogs showed no sign of rejection, and the other three showed minimal to mild lung rejection at the time they were killed. We conclude that a 3-day course of 1.2 mg/kg of FK 506 induced prolonged graft acceptance after lung transplantation in dogs.

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.

Altered cell trafficking in mesenteric lymphoid tissue following syngeneic heterotopic small bowel transplantation in rodents

These data indicate that in rat heterotopic syngeneic SBT, the venous drainage system of the graft has profound effects on cell recovery in the gut-associated lymphoid tissue of both graft and host. Depending on the functional status of the same lymphoid tissue (Gorezynski, personal communication, 1992) one could thus anticipate significant perturbation of host-antigraft (and GVH) reactivity in allogeneic situations according to the venous drainage used. The mechanism(s) responsible for these effects have not been investigated. However, one testable hypothesis is that (a) factor(s) from the gut can control lymphoid recirculation within the mesenteric lymphoid tissue, and that this (these) factor(s) are absorbed under normal circumstances by hepatic tissue.

Comparison of functional activity in host and graft mesenteric lymphoid tissue of rats receiving syngeneic heterotopic small bowel allografts with portal or systemic drainage

With the accompanying paper these studies provide further evidence that functionally important lymphoid cell trafficking takes place in mesenteric tissue under the apparent control of factor(s) filtered by hepatic tissue. The role that these regulatory mechanisms have to play on survival of vascular allografts with venous drainage into either the portal or systemic circulation remains to be elucidated.

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

Immunization of naive or specifically primed C3H/HEJ with irradiated B10.BR spleen cells via the hepatic portal vein leads to an antigen specific decrease in the proliferative and cytotoxic response to B10.BR antigen assayed in vitro (and to increased graft survival of B10.BR grafts in vivo). This effect seems to be mediated in the main by a decrease in IL-2 production from CD4+ T lymphocytes of mice given antigen by the portal route, which is in turn caused by a decreased precursor frequency of IL-2-producing cells. No clear decrease in IL-4 production was seen. Hepatic APC isolated from mice receiving antigen via the portal vein were unable to induce IL-2 production from a C3H/HEJ anti-B10.BR cell line in vitro, in contrast to splenic APC derived from the same mice. Even when antigen was given by conventional (systemic) intravenous routes (in this case via the lateral tail vein) hepatic APC isolated from those mice were unable to stimulate IL-2 production from this cell line. Furthermore, 24 h exposure of a cell line to antigen pulsed hepatic APC left those cells refractory to a subsequent restimulation with antigen presented by splenic APC. Spleen lymphoid cells from primed mice challenged in vivo with B10.BR liver cells (i.v.) were similarly unable to produce IL-2 on rechallenge in vitro with irradiated B10.BR spleen cells, though no defect was seen if in vivo challenge was with B10.BR spleen cells. These data imply that presentation of multiple minor cell surface antigens by hepatic APC leads to specific anergization of IL-2 producing T cells, in a fashion which seems to be distinct from that previously reported as due to 'veto-like' activity.

The Drosophila per gene homologs are expressed in mammalian suprachiasmatic nucleus and heart as well as in molluscan eyes

This study presents evidence for the conservation of Drosophila per gene homologs in mammalian DNA and for their expression in a number of tissues which are involved in various aspects of circadian timekeeping. Distinct 5 kb sequences, which hybridized to a non repetitive fragment of the Drosophila per gene under stringent conditions, were detected by Southern blotting. Sequences homologous to per gene of Drosophila were also amplified from rat and mouse brain cDNA libraries and from a mouse anterior hypothalamus and human hypothalamus libraries. Degenerate PCR primer design was based on conserved segments of the per protein. The per homologs were shown directly (by RT-PCR) to be expressed in hamster and mouse SCN, in hamster heart and in Aplysia and Bulla eyes.

Conditioned stress responses by pregnant and/or lactating mice reduce immune responses of their offspring after weaning

C3H/HEJ mice repeatedly exposed to rotational stress (45 rpm for 30 min) show a decreased immune response after challenge with sheep erythrocytes (SRBC) or multiple minor histoincompatible skin grafts (B10.BR) in association with the cues present when initially exposed to the physical stress. This conditioned immunosuppression is associated with diminished antibody production and enhanced skin graft survival. When previously conditioned mice were mated with normal (nonconditioned) males and reexposed to conditioning cues during pregnancy (days 13, 16, and 19 of gestation), the offspring of these mice were also found to produce a decreased antibody response (and decreased skin graft rejection response) when tested at 7 weeks of age. This altered immune response in the offspring occurred in the absence of any deliberate direct manipulation of these mice. In a further study a reciprocal crossover design was used to investigate whether altered immunity in the offspring was dependent upon the treatment of the biological mother and/or the fostering mother. The most marked immunosuppression was seen in offspring born to, and fostered on, conditioned mothers reexposed to cues previously associated with physical stress. However, even the offspring of of normal C3H/HEJ matings developed a reduced immune response if they were fostered on conditioned mothers reexposed to stress-associated cues. These data imply that the developing immune system is regulated by factors in the colostrum/feto-placental unit which are modified by conditioning phenomena.

Toward an understanding of the mechanisms of classical conditioning of antibody responses

Mice of different ages were subjected to repeated exposure to cyclophosphamide:saccharin (conditioned), or cyclophosphamide:saccharin followed by saccharin only (extinguished). Only young animals in the former group showed a decreased IgG antibody-forming-cell (AFC) response after challenge with sheep erythrocytes (SRBC) in the presence of saccharin. When irradiated conditioned young animals were used as recipients of antigen-challenged spleen cells from nonconditioned mice they were found to support a greater immune response than nonconditioned recipients. Similarly, cells from conditioned young mice gave a greater immune response in naive recipients than did cells from nonconditioned mice. Only when cells from conditioned young mice rather than conditioned "aged" mice were studied in irradiated conditioned young recipients was immunosuppression observed. These data are most consistent with a specific host cell:environment interaction being responsible for the conditioned immunosuppression observed in young mice. A deficit in both cells/environment apparently occurs during aging. At least one of these deficiencies seems related to loss of a suppressor T-cell population with age in conditioned mice.

Specific manipulation in vivo of immunity to skin grafts bearing multiple minor histocompatibility differences

Naive CBA mice injected with AKR spleen cells via the portal vein (p.v.) subsequently showed decreased stimulation in vitro in a primary MLR or cell-mediated lympholysis assay with irradiated AKR stimulator cells. No inhibition of stimulation by B10.BR cells is seen. These mice also show specific prolongation of survival of AKR skin grafts in vivo and diminished capacity for in vivo priming for (secondary) anti-AKR responses in vitro. These effects are not seen if initial challenge is with AKR cells injected subcutaneously (s.c.) or via the lateral tail vein (i.v.). Moreover, if immune CBA anti-AKR mice are similarly challenged with AKR cells via the portal vein, no suppression of anti-AKR immunity is elicited, as determined by subsequent in vitro assays or in vivo graft rejection. However, spleen cells from CBA anti-AKR immune mice can be used to induce, in further naive CBA mice, a specific suppression of subsequent anti-AKR graft reactivity (assayed in vitro or in vivo). Active T cell-mediated suppression can be documented using both these protocols though the additional involvement of specific serum-mediated suppression cannot be eliminated.

Antigenic variation in Leishmania mexicana following infection of immunized mice leads to relative sparing of suppressor determinants

Intravenous immunization of BALB/c mice with irradiated Leishmania mexicana slows the growth of a subsequent intradermal inoculation of virulent parasites. Prior subcutaneous immunization with irradiated parasites before i.v. immunization blocks the protective effect of the latter. Parasites harvested from vaccinated mice grow more slowly in naive mice than the initial inoculated clone, and have a diminished capacity to immunize mice against this initial clone when used as (irradiated) i.v. immunogen. However, parasites harvested from vaccinated mice are as effective as the initial clone in blocking protection when used as subcutaneous immunogen. Understanding the nature of this differential response in expression of protecting/suppressor determinants in parasites harvested from vaccinated or naive mice will likely be important to developing a suitable vaccination strategy for human use.

Conditioned enhancement of skin allografts in mice

Healthy A/J mice grafted with either BALB/c or C57BL/6 tail skin routinely reject these grafts with a mean survival time (MST) of 12-14 days. Low dose cyclophosphamide, Cy (50 mg/kg) on the day of engraftment can enhance survival of both grafts (MST 17-20 days). If mice are given three weekly intravenous injections of BALB/c peripheral blood prior to grafting, specific enhancement of BALB/c but not C57BL/6 grafts results (MST 18 and 12 days, respectively). Mice given several ip treatments with Cy in association with a novel taste (saccharin, Sacc) in their drinking water also show a conditioned immunosuppression if subsequently exposed to Sacc alone. Such mice given BALB/c or C57BL/6 skin grafts and re-exposed to Sacc also show prolonged survival of these skin allografts (MST 16-17 days). If conditioned mice are also treated, by pretransplant donor-specific transfusion, to develop a state of specific suppression of allograft immunity, then subsequent grafting with BALB/c or C57BL/6 grafts coupled with re-exposure to Sacc lead to a further prolonged survival of grafts specifically in the BALB/c mice (MST 29 days).

Comparison of endotoxins and cutaneous burn toxin as immunosuppressants

Endotoxins of E. coli, S. typhosa and Ps. aeruginosa were injected i.p. into mice a few days before administration of the antigen sheep erythrocytes (SE). Antibody-forming cells (AFC) to SE were later enumerated in relation to dose of endotoxin given. In comparison a toxic lipid protein isolated from burned skin (cutaneous burn toxin or CBT) was similarly applied and found to be more inhibitory of the immune response than any of the three endotoxins. Considering the 50 per cent inhibitory doses on a molar basis CBT was found to be 1000 fold more immunosuppressive than the most inhibitory endotoxin. As the immune suppression which follows severe thermal injury involves failure of interleukin 2 (IL2) function, as a critical index of survival, the CBT was tested for its effects on the culture of a human IL2-dependent cell line in the presence of IL2. CBT inhibited the growth of these cells, however, endotoxin had no effect on their proliferation. Thus CBT, which arises by a thermally induced polymerization of skin lipid protein, is specific to burn injury and has a direct inhibitory effect on the immune response.

Neuroleptic and anti-depressant drug treatment abolishes conditioned immunosuppression in mice

Mice previously exposed to cyclophosphamide in the presence of saccharin-flavored water will show a decreased antibody response to challenge with sheep erythrocytes if simultaneously they are again given saccharin to drink. These mice also show conditioned taste aversion. Treatment of conditioned animals with chlorpromazine or amitriptyline after challenge with erythrocytes in the presence of saccharin reduced the degree of immunosuppression and, though to a lesser degree, the conditioned taste aversion.

Altered virulence and vaccination properties of Leishmania parasites grown in infected vaccinated mice

BALB/c mice, which are normally highly susceptible to growth of Leishmania mexicana parasites in vivo, can be vaccinated with avirulent temperature-sensitive mutants of L. mexicana so that challenge with virulent organisms results in markedly diminished growth of the latter. Parasites extracted from the lesions which do appear in these mice are able to produce active infection in secondary hosts, although the rate of progression of these lesions is slower than that seen with the original virulent cloned organism. Interestingly, when irradiated parasites from the secondary hosts are themselves used to vaccinate naive BALB/c mice, less protection is seen than when irradiated virulent organisms from the initial infecting clone are used. These data suggest that when infection does take place in mice vaccinated with avirulent clones of parasite, the organisms which develop in lesions in these animals are substantially modified from those present in the initial infecting inoculum.

IL-2 secretion is pertussis toxin sensitive in a T lymphocyte hybridoma

Interaction of specific ligands with TCR initiates a cascade of biochemical events which leads to expression of high affinity IL-2R and subsequent IL-2 secretion. Activation of phospholipase C (PL-C) is considered to be a key event in the initiation of this cascade. However, in addition to this PL-C-dependent pathway, PL-C-independent pathways have been hypothesized. Identification of the steps constituting these PL-C-independent pathways has been difficult because activation of PL-C and the subsequent cascade of events mask the effects of such pathways. Specific inhibitors for PL-C, or mutants defective in, the PL-C pathway would facilitate delineation of alternative activation pathways. We have identified a murine pork insulin/IAd-specific T cell hybridoma, B8P3.11, in which perturbation of the B8P3.11 TCR by either Ag in association with Ia, anti-CD3 antibodies, or a mitogenic lectin does not induce increases in myo-inositol 1,4,5-triphosphate production or cytosolic free calcium, yet it does lead to IL-2 secretion. Treatment of B8P3.11 with pertussis toxin, at concentrations which ADP-ribosylate GTP-binding proteins, inhibits IL-2 secretion. Thus, signal transduction resulting in IL-2 secretion by B8P3.11 likely involves a G protein. In contrast, TCR/ligand interaction activates the PL-C-dependent pathway in LBRM 331A5, a T cell lymphoma. Furthermore, pertussis toxin treatment, which blocks IL-2 secretion by B8P3.11, does not alter IL-2 secretion by LBRM 331A5. However, similar pertussis toxin substrates are present in both cells. Therefore, B8P3.11 T cells should help to elucidate PL-C-independent activation pathways.

IL-2 secretion is pertussis toxin sensitive in a T lymphocyte hybridoma

Interaction of specific ligands with TCR initiates a cascade of biochemical events which leads to expression of high affinity IL-2R and subsequent IL-2 secretion. Activation of phospholipase C (PL-C) is considered to be a key event in the initiation of this cascade. However, in addition to this PL-C-dependent pathway, PL-C-independent pathways have been hypothesized. Identification of the steps constituting these PL-C-independent pathways has been difficult because activation of PL-C and the subsequent cascade of events mask the effects of such pathways. Specific inhibitors for PL-C, or mutants defective in, the PL-C pathway would facilitate delineation of alternative activation pathways. We have identified a murine pork insulin/IAd-specific T cell hybridoma, B8P3.11, in which perturbation of the B8P3.11 TCR by either Ag in association with Ia, anti-CD3 antibodies, or a mitogenic lectin does not induce increases in myo-inositol 1,4,5-triphosphate production or cytosolic free calcium, yet it does lead to IL-2 secretion. Treatment of B8P3.11 with pertussis toxin, at concentrations which ADP-ribosylate GTP-binding proteins, inhibits IL-2 secretion. Thus, signal transduction resulting in IL-2 secretion by B8P3.11 likely involves a G protein. In contrast, TCR/ligand interaction activates the PL-C-dependent pathway in LBRM 331A5, a T cell lymphoma. Furthermore, pertussis toxin treatment, which blocks IL-2 secretion by B8P3.11, does not alter IL-2 secretion by LBRM 331A5. However, similar pertussis toxin substrates are present in both cells. Therefore, B8P3.11 T cells should help to elucidate PL-C-independent activation pathways.

Interactions between lymphoid cells and a thymic stromal cell line in vitro

In the present study, we have optimalized the adherence assay to allow monitoring of the level of contact between thymocytes and a thymic epithelial cell line, E-5, in vitro. This type of interaction is not MHC-restricted, thus is unlikely to participate in the education of thymocytes to self. It was also shown that adherence does not vary from strain to strain, except for B6lpr/lpr immunodeficient mice which showed a markedly decreased adherence. This might be caused by the high level of L3T4-, Lyt-2- thymocytes in these mice (Davignon et al., 1985), since enriched double negative cells were shown not to adhere to E-5 cells. Preliminary characterization of adhering thymocytes suggests an heterogeneous mature phenotype. These cells appear around day 16 of fetal life and increase gradually until birth to remain constant throughout life. On the basis of contact duration, two populations of adhering thymocytes exist: one spontaneously detached after 1.5 hr, refractive to further adherence and the other which adheres for up to 14 hr. Contact between lymphoid and E-5 cells was shown to induce PHA responsiveness.

Conditioned immunosuppression in young versus aged mice: differences in cells and responses to environmental stimuli lead to altered conditioning in aged animals

Aged mice (greater than 20 months of age) show a decreased immune response after antigen challenge compared to their young counterparts. In this study aged mice were also found to show a diminished conditioned immunosuppression after associative learning trials with cyclophosphamide and saccharin, followed by immune stimulation in the presence of saccharin, when compared to young (10 weeks) syngeneic mice. Adoptive transfer experiments in which cells from nonconditioned or conditioned young or aged mice were injected into irradiated conditioned young or aged syngeneic mice (exposed or not exposed to conditioned stimuli) revealed the following: (1) There was an altered responsiveness of normal cells injected into conditioned aged mice (reexposed to cues) compared to the response in young recipients; (2) Cells from conditioned young mice failed to show conditioned immunosuppression on adoptive transfer to irradiated conditioned aged mice; (3) Cells from conditioned aged mice failed to show conditioned immunosuppression on adoptive transfer to irradiated conditioned young mice; (4) The changes seen in spleen cells from conditioned aged mice (relative to similar cells from young mice) were to be found in the T cell population of these animals. These data are consistent with the idea that during aging changes in both the responding cells and the conditioned environment, along with the interaction of these, produce a decreased ability to document conditioned immunosuppression of antibody responses.

Immunization with Leishmania-specific T cell not B cell lines or hybridomas can modulate the response of susceptible mice infected with viable parasites

Monoclonal antibodies (mAb), T cell lines, and T or B cell hybridomas were prepared from BALB/c, CBA, or E1 mice infected with Leishmania mexicana. Various mAb were produced which inhibited the growth and motility of parasites in vitro. T cell lines (hybridomas) were screened for their ability to release interleukin 2 on specific antigen exposure. Passive transfer of mAb or T cell lines to infected adult mice caused little perturbation of parasite growth. Recipient naive mice were immunized with purified Ig or irradiated cells from these sources and were subsequently infected with viable parasites. Only preimmunization with T cell lines (hybridomas) led to exacerbation of parasite growth, although enzyme-linked immunosorbent assays could detect the production of anti-idiotype antibodies in mAb (B cell hybridoma)-immunized mice. Either nylon wool-purified T cells or serum Ig from T cell-immunized mice could be used to immunize further naive recipients for protection against parasite growth. These data have implications for the development of anti-idiotype vaccines for Leishmania antigens.

Immunization with Leishmania-specific T cell not B cell lines or hybridomas can modulate the response of susceptible mice infected with viable parasites

Monoclonal antibodies (mAb), T cell lines, and T or B cell hybridomas were prepared from BALB/c, CBA, or E1 mice infected with Leishmania mexicana. Various mAb were produced which inhibited the growth and motility of parasites in vitro. T cell lines (hybridomas) were screened for their ability to release interleukin 2 on specific antigen exposure. Passive transfer of mAb or T cell lines to infected adult mice caused little perturbation of parasite growth. Recipient naive mice were immunized with purified Ig or irradiated cells from these sources and were subsequently infected with viable parasites. Only preimmunization with T cell lines (hybridomas) led to exacerbation of parasite growth, although enzyme-linked immunosorbent assays could detect the production of anti-idiotype antibodies in mAb (B cell hybridoma)-immunized mice. Either nylon wool-purified T cells or serum Ig from T cell-immunized mice could be used to immunize further naive recipients for protection against parasite growth. These data have implications for the development of anti-idiotype vaccines for Leishmania antigens.

Cyclosporin alters the induction of allospecific tolerance in vivo

CBA mice were made hyporesponsive to A/J alloantigens by either neonatal inoculation of (CBA X A)F1 hybrid lymphoid cells or by intravenous injection of adult mice with A/J bone marrow cells. Specific alloreactivity was assessed in vitro by induction of anti-A/J cytotoxic T lymphocytes (CTL) or in vivo by skin graft rejection. Cyclosporin A given at the same time as the tolerance-inducing regimen of F1 (or parental) lymphoid cells abolished the hyporesponsiveness normally induced by these injections.