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M Sykes

Publications and source records attributed to M Sykes.

At least 163 records · Page 9Linked to original sources
PubMed1991

Mechanism of the anti-GVHD effect of IL-2. I. Protective host-type cell populations are not induced by IL-2 treatment alone.

We have recently demonstrated that high-dose IL-2 administered for a short period (2.5 days) beginning on the day of bone marrow transplantation mediates a marked protective effect against GVHD in mice, while preserving the ability to achieve alloengraftment (1). This protective effect is augmented by administration of T cell-depleted (TCD) syngeneic marrow, and is dependent upon early administration of IL-2 (1). The graft-vs-tumor effect against the EL4 leukemia/lymphoma is not diminished in animals protected from GVHD by IL-2 (2). In an attempt to determine whether or not IL-2-activated host-type cells might be responsible for GVHD protection, we have now performed adoptive transfer studies. The results failed to provide evidence that treatment of lethally irradiated mice with IL-2 activates protective host-derived or syngeneic marrow-derived cell populations which can be adoptively transferred to lethally irradiated secondary recipients receiving allogeneic GVHD-producing inocula. Likewise, treatment of lethally irradiated mice with a complete 2.5-day course of IL-2 prior to administration of allogeneic inocula did not lead to GVHD protection. These results suggest that either IL-2 directly inhibits the GVH reactivity of allogeneic GVH-reactive cells, or that GVH reactivity is attenuated by IL-2 during the period of interaction of donor- and host-type cells.

Animals↗
PubMed1990

Unusual T cell populations in adult murine bone marrow. Prevalence of CD3+CD4-CD8- and alpha beta TCR+NK1.1+ cells.

The T cell populations present in normal murine bone marrow have not been previously analyzed in detail, mainly because of their relative rarity. In order to permit such analyses, bone marrow T cells were enriched by depleting Mac1-positive cells, which constitute 65 to 90% of bone marrow cells (BMC), and then studied by two-color flow cytometry. Analysis of the remaining cells revealed that the T cell profile of adult murine bone marrow is markedly different from that of other lymphoid organs. A very high proportion of bone marrow CD3+ cells (approximately one-third) are CD4-CD8-. CD3+CD4-CD8- cells are much more concentrated among BMC T cells than among thymocytes or splenic T cells, suggesting that bone marrow may be either a site of extrathymic TCR gene rearrangement, or a major site to which such cells home from the thymus. The expression of NK1.1 was also evaluated on Mac1-depleted BMC populations. Surprisingly, up to 39% of alpha beta TCR+ BMC were found to express NK1.1. Most alpha beta TCR+NK1.1+ BMC also expressed CD4 or CD8. NK1.1+ alpha beta TCR+ cells represented a much greater proportion of BMC T cells than of other lymphoid (splenocyte or thymocyte) T cell populations. Mac1-depleted BMC of nude mice contained very few cells with this phenotype. These results are consistent with the hypothesis that NK1.1+ alpha beta TCR+ cells are generated primarily in the thymus of normal animals and migrate preferentially to bone marrow, where they may function as regulatory elements in hematopoiesis.

Animals↗
PubMed1990

Specific tolerance induction across a xenogeneic barrier: production of mixed rat/mouse lymphohematopoietic chimeras using a nonlethal preparative regimen.

The development of safe methods for inducing donor-specific tolerance across xenogeneic barriers could potentially relieve the critical shortage of allograft donors that currently limits the applicability of organ transplantation. We report here that such tolerance can be induced in a xenogeneic combination (rat----mouse) using a nonmyeloablative and nonlethal preparative regimen. Successful induction of chimerism and donor-specific transplantation tolerance required pretreatment of recipients with monoclonal antibodies (mAbs) against NK1.1, Thy-1.2, CD4 and CD8, followed by administration of 3 Gy whole body radiation (WBI), 7 Gy thymic irradiation, and infusion of T cell-depleted rat bone marrow cells (BMC). Rat cells appeared among peripheral blood lymphocytes (PBL) of such recipients by 2-3 wk, and rat T cells by 2-5 wk following bone marrow transplantation (BMT). Donor-type rat skin grafts placed 4 mo after BMT were accepted, while simultaneously placed non-donor-type rat skin grafts were promptly rejected. In addition to its clinical potential, the ability to induce donor-specific tolerance across xenogeneic barriers using such a nonlethal preparative regimen provides a valuable model for the study of mechanisms of xenogeneic transplantation tolerance.

Animals↗
PubMed1990

In vivo administration of interleukin 2 plus T cell-depleted syngeneic marrow prevents graft-versus-host disease mortality and permits alloengraftment.

Previous work from this laboratory has demonstrated that T cell-depleted (TCD) syngeneic marrow can delay, but not prevent, the mortality from acute graft-vs.-host disease (GVHD) caused by MHC-mismatched lymphoid cells administered to lethally irradiated mice. We demonstrate here that a protective effect against GVHD is also observed after in vivo treatment with IL-2. Administration of 10,000-50,000 U of IL-2 twice daily for the first 5 d after bone marrow transplantation markedly reduced the mortality from both acute and chronic GVHD induced across complete MHC barriers in lethally irradiated mice, and frequently led to long-term survival. Complete allogeneic reconstitution was demonstrated in all long-term survivors of this treatment regimen. While either IL-2 or TCD syngeneic marrow administered alone was protective in some experiments, the maximal protective effect was observed after administration of both IL-2 and TCD syngeneic marrow, especially when the effects of IL-2 were suboptimal. The timing of IL-2 administration was critical to this beneficial effect, since a delay of 7 d in commencing IL-2 treatment was associated with accelerated GVHD mortality. This new approach to the prevention of GVHD permits the administration of allogeneic T cells, and may therefore avoid the increased incidence of graft failure and loss of antileukemic effects associated with the T cell depletion of allogeneic marrow, which is otherwise required for the prevention of GVHD.

Animals↗
PubMed1990

Natural suppressor cells in spleens of irradiated, bone marrow-reconstituted mice and normal bone marrow: lack of Sca-1 expression and enrichment by depletion of Mac1-positive cells.

We have recently reported the development of natural suppressor (NS) cells in lethally irradiated, bone marrow-reconstituted mice during the early weeks after bone marrow transplantation (BMT). These cells were shown to be derived primarily from the syngeneic marrow component in recipients of mixed allogeneic plus syngeneic (host type) marrow, and it was speculated that they might be responsible for the anti-GVHD effect previously described for T-cell-depleted syngeneic marrow. It was therefore of interest to look for such suppressive activity in normal adult bone marrow, which might serve as an obtainable source of such cells if they were to be isolated and used clinically. Such activity has indeed been found in normal adult bone marrow and its characteristics compared to that in spleens of early BMT recipients. Suppressive cells from both sources were similar in their specificity patterns and radiosensitivity, and were of the null (i.e., non-T, non-B, nonmacrophage) cell phenotype. Suppression from either source can be enriched by removal of Mac1-positive cells, providing a possible approach to obtaining NS-enriched populations for in vitro expansion and adoptive transfer studies. Such depletion of Mac1-positive cells was associated with a threefold enrichment of Thy1-positive cells, of which one half were CD4- and CD8-negative, similar to the reported phenotype of cultured NS cell lines. Even when enriched in this manner, the contribution of Thy1-positive cell populations did not reach statistical significance. A recent report has suggested that NS cells might actually be pluripotent hematopoietic stem cells. In contrast, we report here that depletion of Sca1-positive pluripotent hematopoietic stem cells with monoclonal antibody plus immunomagnetic beads does not remove NS activity.

Animals↗
PubMed1990

In vitro and in vivo analysis of bone marrow-derived CD3+, CD4-, CD8-, NK1.1+ cell lines.

The development of methods of avoiding graft-versus-host disease (GVHD) while retaining the alloengraftment-promoting and anti-leukemic effects of allogeneic T cells is a major goal of research in bone marrow transplantation (BMT). We have recently obtained evidence suggesting that natural suppressor (NS) cells derived from T cell-depleted (TCD) syngeneic marrow can protect against GVHD while permitting alloengraftment. We have now attempted to enrich and then propagate NS cells in vitro, with the goal of obtaining an enhanced anti-GVHD effect by adoptive transfer in vivo. Two long-term cell lines were generated culturing BMC depleted of Mac1-positive cells and of Mac1-positive plus Thy1-positive cells in high concentrations of IL-2. Both cell lines showed anti-GVHD effects when administered along with a GVHD-producing inoculum, while permitting complete allogeneic reconstitution. A clone derived from Mac1-depleted BMC protected completely against a more chronic pattern of GVHD. These cell lines demonstrated suppressive activity in vitro, cytolytic activity against a broad range of natural killer (NK)-sensitive and NK-resistant targets, and a novel cell surface phenotype, with characteristics of both alpha beta-TcR-bearing T cells and of NK cells. In some respects, these cells resemble LAK cells and differ from fresh NS cells, and from the cloned NS cells derived from spleens of total lymphoid irradiation (TLI)-treated mice and neonatal mice. To our knowledge, this is the first detailed phenotypic analysis of cell lines with in vivo anti-GVHD activity. If applicability can be demonstrated in large animal models, the ability to use bone marrow as a source of such protective cell lines might also have potential utility in clinical BMT.

Animals↗
PubMed1990

Interleukin 2 prevents graft-versus-host disease while preserving the graft-versus-leukemia effect of allogeneic T cells.

We have recently demonstrated that interleukin 2 (IL-2), when administered in high doses for several days beginning on the day of allogeneic bone marrow transplantation (BMT), markedly diminishes graft-versus-host disease (GVHD) mortality in lethally irradiated mice. An optimal anti-GVHD effect was attained by coadministering T-cell-depleted (TCD) syngeneic marrow. We demonstrate here that the full graft-versus-leukemia effect of allogeneic T lymphocytes is obtained even when GVHD is markedly diminished by the coadministration of IL-2 and TCD syngeneic marrow. This methodology represents an approach to the treatment of leukemia in which the beneficial effects of allogeneic T cells can be exploited while their major deleterious effect, GVHD, is avoided. These results may thus have an impact on the clinical use of BMT for the treatment of hematologic malignancies.

Animals↗
PubMed1990

Bone marrow transplantation as a means of inducing tolerance.

Successful induction of bone marrow chimerism is the most potent means of inducing specific transplantation tolerance across major histocompatibility barriers. Reliable, non-toxic methods of achieving such chimerism could obviate the need for chronic immunosuppressive therapy in clinical organ transplantation. Some novel conditioning protocols have recently been developed which permit the achievement of this goal in animal models. Recent developments have led to a greater understanding of the mechanisms leading to the induction of tolerance in each of these models.

Animals↗
PubMed1989

Effects of T cell depletion in radiation bone marrow chimeras. III. Characterization of allogeneic bone marrow cell populations that increase allogeneic chimerism independently of graft-vs-host disease in mixed marrow recipients.

The opposing problems of graft-vs-host disease vs failure of alloengraftment severely limit the success of allogeneic bone marrow transplantation as a therapeutic modality. We have recently used a murine bone marrow transplantation model involving reconstitution of lethally irradiated mice with mixtures of allogeneic and syngeneic marrow to demonstrate that an allogeneic bone marrow subpopulation, removed by T cell depletion with rabbit anti-mouse brain serum and complement (RAMB/C), is capable of increasing levels of allogeneic chimerism. This effect was observed in an F1 into parent genetic combination lacking the potential for graft-vs-host disease, and radiation protection studies suggested that it was not due to depletion of stem cells by RAMB/C. We have now attempted to characterize the cell population responsible for increasing allogeneic chimerism in this model. The results indicate that neither mature T cells nor NK cells are responsible for this activity. However, an assay involving mixed marrow reconstitution in an Ly-5 congenic strain combination was found to be more sensitive to small degrees of stem cell depletion than radiation protection assays using three-fold titrations of bone marrow cells. Using this assay, we were able to detect some degree of stem cell depletion by treatment with RAMB/C, but not with anti-T cell mAb. Nevertheless, if the effects of alloresistance observed in this model are considered, the degree of stem cell depletion detected by such mixing studies in insufficient to account for the effects of RAMB/C depletion on levels of allogeneic chimerism, suggesting that another cell population with this property remains to be identified.

Animals↗
PubMed1989

Antiviral T cell competence and restriction specificity of mixed allogeneic (P1 + P2----P1) irradiation chimeras.

Mixed irradiation bone marrow chimeras were prepared by reconstituting lethally irradiated C57BL/10 (B10) or B10.D2 mice with T cell-depleted bone marrow cells of B10 plus B10.D2 origin. These chimeras were healthy and survived well under conventional housing conditions and after experimental laboratory infections. Of a total of 17 chimeras tested, 2 died spontaneously or from the injected virus. Twelve of fifteen chimeras mounted a measurable cytotoxic T cell response to virus. Despite approximately equal percentages of B10 and B10.D2 lymphocytes in chimeras, cytotoxic T cell responses to vaccinia virus and lymphocytic choriomeningitis virus were mediated variably by either syngeneic or allogeneic donor lymphocytes; thus the H-2 type of effector T cells frequently did not correspond to the 50:50 distribution of spleen or peripheral blood lymphocytes. Cytotoxic responses were restricted exclusively to recipient H-2 type. All mixed chimeras examined were able to mount a good IgG response to vesicular stomatitis virus. These results confirm previous data suggesting that such mixed chimeras are healthy and immunocompetent and demonstrate strict recipient-determined restriction specificity of effector T cells; they also suggest that if T help is necessary for induction of virus-specific cytotoxic T cells, it does not require host-restricted interactions between helper T cells and precursor cytotoxic T cells.

Animals↗
PubMed1989

Effects of streptozocin-induced diabetes on glucose metabolism and lactate release by isolated fat cells from young lean and older, moderately obese rats.

Streptozocin-induced diabetes (STZ-D) was produced in male Wistar rats at two stages of development: young, lean rats, weighing 150-220 g (6-8 wk), and older, moderately obese rats, weighing 450-500 g (6-8 mo). A comparable degree of hyperglycemia (420-500 mg/dl) without ketosis was generated by injection of 50 mg/kg i.v. STZ for young, lean rats and 30 mg/kg i.v. for older, fatter rats. The animals were killed 8-11 days after injection. Insulin binding by the isolated adipocytes of both groups was not significantly altered on a per-cell basis by the presence of diabetes. Total adipocyte glucose metabolism, both basal and insulin stimulated, was reduced (63 and 88%, respectively) by the induction of diabetes in young, lean rats. In contrast, the induction of diabetes in the older, moderately obese rats had no suppressive effect on total glucose metabolism by their fat cells. Diabetes increased the relative conversion of glucose to lactate by fat cells from both groups of rats, but in absolute terms, the fat cells from the obese diabetic rats produced significantly more lactate from glucose than cells from the lean diabetic rats, both in the absence and presence of insulin. Diabetes did not alter the glucose concentration at which peak insulin response occurred in either group. We conclude that STZ-D in rats, at different stages of development and degrees of adiposity, results in quantitatively different alterations of adipocyte metabolism, which appear to be postreceptor in nature and result in an increase in glucose conversion to lactate.

Adipose Tissue↗
PubMed1989

Suppressive activity in recipients of non-T cell-depleted allogeneic bone marrow transplants: role of T cell-depleted syngeneic marrow.

The co-administration of T cell-depleted (TCD) syngeneic marrow protects against the acute graft-versus-host disease (GVHD) mortality which follows the administration of allogeneic bone marrow and lymphocytes to lethally irradiated mice. We have previously hypothesized that natural suppressor (NS) cells, which are present in the spleens of radiation chimeras in the early weeks after bone marrow transplantation (BMT), might be responsible for this protective effect. This hypothesis was based on the observation that NS activity in the spleens of recipients of mixed marrow inocula is mediated predominantly by cells derived from the syngeneic marrow component. This observation, however, was made in recipients of mixed inocula in which both the allogeneic and the syngeneic marrow components had been TCD. Such an approach was taken in order to avoid administration of allogeneic T cells and the suppressive activity which might develop due to the GVH reaction itself. It was, however, of interest to examine the suppressive activity developing in recipients of non-TCD allogeneic marrow plus TCD syngeneic marrow, since the anti-GVHD effects of host-type putative suppressor cells might be clinically relevant. The results presented here demonstrate that non-T cell-mediated suppressive activity develops in the spleens of recipients of non-TCD allogeneic marrow, consistent with the activity of NS cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

The recovery of resistance to alloengraftment following lethal irradiation and administration of T cell-depleted syngeneic bone marrow.

Recent studies from this laboratory have shown that unmanipulated, MHC-mismatched allogeneic bone marrow (BM) engrafts and produces complete allogeneic chimerism when administered to recipient mice 8 days following lethal irradiation and reconstitution with T cell-depleted (TCD) syngeneic bone marrow. Host lymphopoietic recovery thus appears to be insufficient by 8 days after irradiation and TCD syngeneic bone marrow transplantation (BMT) to resist alloengraftment. In the present studies we have examined the development of such resistance to alloengraftment by determining the limits of the time period permitting engraftment, and have assessed the role of allogeneic T cells in achieving chimerism after delayed allogeneic bone marrow transplantation. Our results indicate that increasing the delay for more than 8 days following irradiation and TCD syngeneic BMT leads to a rapid loss of the ability to achieve alloengraftment by non-TCD allogeneic bone marrow. Removal of T cells from allogeneic BM inocula administered 8 days after irradiation and TCD syngeneic BMT resulted in loss of the ability to achieve alloengraftment. Repopulation patterns in host spleens following delayed reconstitution suggest that active elimination of engrafted syngeneic lymphohemopoietic elements is necessary to permit engraftment of allogeneic marrow administered after such a delay.

Animals↗
PubMed1989

Graft-versus-leukemia effect using mixed allogeneic bone marrow transplantation.

Previous studies have demonstrated that T cell-depleted (TCD) syngeneic marrow protects against graft-versus-host disease (GVHD) when given along with an allogeneic lymphocyte plus bone marrow (BM) inoculum to lethally irradiated mice. In spite of this anti-GVHD effect, TCD syngeneic marrow is ultimately eliminated by non-TCD allogeneic marrow, permitting complete allogeneic reconstitution. These observations suggested that allogeneic BM might also eliminate host-type leukemic cells in a model in which TCD syngeneic marrow is co-administered to provide protection from GVHD. In the present studies, we describe the establishment of a new model using the EL4 leukemia/lymphoma. Lethally irradiated B10 (H-2b) mice were given a lethal dose of EL4 cells (H-2b) along with syngeneic marrow or a mixture of TCD syngeneic plus non-TCD allogeneic (B10.D2, H-2d) marrow. Non-TCD allogeneic marrow, in contrast to TCD or unmanipulated syngeneic marrow, delayed or prevented mortality from the otherwise lethal EL4 inoculum, without producing clinically apparent GVHD. The anti-leukemic effect of allogeneic marrow alone was not attenuated by the co-administration of TCD syngeneic marrow, and such animals repopulated as completely allogeneic chimeras. Similar anti-leukemic effects of mixed marrow inocula in a haploidentical strain combination, and an anti-leukemic effect against established tumor were also demonstrated. This model may have the potential to increase the safety of clinical bone marrow transplantation across greater HLA disparities, while permitting utilization of the anti-leukemic and alloengraftment-promoting effects of T cells in allogeneic marrow inocula.

Animals↗
PubMed1988

Graft-versus-host-related immunosuppression is induced in mixed chimeras by alloresponses against either host or donor lymphohematopoietic cells.

Graft-vs.-host (GVH)-related immunosuppression has previously been demonstrated in F1 rodent recipients of parental lymphoid cells, and has been thought to result from an immunologic attack of the donor against the host. Since all cells of such F1 recipients could potentially bear target class I MHC alloantigens, it has not previously been possible to determine precisely the target tissues responsible for development of GVH-related effects. In the present studies we have used mixed allogeneic chimeras as recipients of host or donor-strain lymphocyte inocula, and have made the surprising observation that "GVH-induced" immune unresponsiveness does not require GVH reactivity, per se, but develops in the presence of a one-way alloresponse against lymphohematopoietic cells in either the GVH or the host-versus-graft direction.

Animals↗
PubMed1988

Effects of T cell depletion in radiation bone marrow chimeras. I. Evidence for a donor cell population which increases allogeneic chimerism but which lacks the potential to produce GVHD.

The opposing problems of graft-vs-host disease (GVHD) and failure of alloengraftment present major obstacles to the application of bone marrow transplantation (BMT) across complete MHC barriers. The addition of syngeneic T-cell-depleted (TCD) bone marrow (BM) to untreated fully allogeneic marrow inocula in lethally irradiated mice has been previously shown to provide protection from GVHD. We have used this model to study the effects of allogeneic T cells on levels of chimerism in recipients of mixed marrow inocula. The results indicate that T cells in allogeneic BM inocula eliminate both coadministered recipient-strain and radioresistant host hematopoietic elements to produce complete allogeneic chimerism without clinical GVHD. To determine the role of GVH reactivity in this phenomenon, we performed similar studies in an F1 into parent combination, in which the genetic potential for GVHD is lacking. The presence of T cells in F1 marrow inocula led to predominant repopulation with F1 lymphocytes in such chimeras, even when coadministered with TCD-recipient-strain BM. These results imply that the ability of allogeneic BM cells removed by T cell depletion to increase levels of allochimerism may be mediated by a population which is distinct from that which produces GVHD. These results may have implications for clinical BM transplantation.

Animals↗
PubMed1988

Effects of T cell depletion in radiation bone marrow chimeras. II. Requirement for allogeneic T cells in the reconstituting bone marrow inoculum for subsequent resistance to breaking of tolerance.

The ability of normal recipient-type lymphocytes to break tolerance in long-term allogenic radiation chimeras has been investigated. Reconstitution of lethally irradiated mice with a mixture of syngeneic and allogeneic T cell-depleted (TCD) bone marrow (BM) has previously been shown to lead to mixed chimerism and permanent, specific tolerance to donor and host alloantigen (3-5). If allogeneic T cells are not depleted from the reconstituting inoculum, complete allogeneic chimerism results; however, no clinical evidence for GVHD is observed, presumably due to the protective effect provided by syngeneic TCD BM. This model has now been used to study the effects of allogenic T cells administered in reconstituting BM inocula on stability of long-term tolerance. We have attempted to break tolerance in long-term chimeras originally reconstituted with TCD or non-TCD BM by challenging them with inocula containing normal, nontolerant recipient strain lymphocytes. tolerance was broken with remarkable ease in recipients of mixed marrow inocula in which both original BM components were TCD. In contrast, tolerance in chimeras originally reconstituted with non-TCD allogeneic BM was not affected by such inocula. Susceptibility to loss of chimerism and tolerance was not related to initial levels of chimerism per se, but rather to T cell depletion of allogeneic BM, since chimeras reconstituted with TCD allogeneic BM alone (mean level of allogeneic chimerism 98%) were as susceptible as mixed chimeras to the tolerance-breaking effects of such inocula. The possible contribution of GVH reactivity to this resistance was investigated using an F1 into parent strain combination. In these animals, the use of non-TCD F1 BM inocula for reconstitution did not lead to resistance to the tolerance-breaking effects of recipient strain splenocytes. These results suggest that the ability of T cells in allogeneic BM inocula to confer resistance to late graft failure may be related to their graft-vs.-host reactivity, even in situations in which they do not cause clinical GVHD. These findings may have relevance to the mechanism whereby T cell depletion of allogeneic BM leads to an increased incidence of late graft failure in clinical BM transplantation situations.

Animals↗