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M W Flye

Publications and source records attributed to M W Flye.

At least 109 records · Page 6Linked to original sources
PubMed1993

MHC class II presenting cells are necessary for the induction of intrathymic tolerance.

OBJECTIVE: This study determined the form of cellular donor MHC alloantigen necessary for the induction of intrathymic tolerance. BACKGROUND: The authors have achieved indefinite donor-specific tolerance, to a fully MHC-disparate rat heterotopic cardiac allograft, after the pretransplant intrathymic injection of unfractionated donor splenocytes and a single injection of rabbit anti-rat lymphocyte serum (ALS), without subsequent immunosuppression. METHODS: Male 4-12-week-old Buffalo (RT1b) rats underwent an intrathymic injection of either fractionated Lewis (RT1(1)) red blood cells (purified by Ficoll gradient) or T lymphocytes (purified by nylon wool column and plastic adherence), both of which express only MHC class I alloantigens, or B lymphocytes, macrophages, and dendritic cells (purified by plastic adherence) which express both MHC class I and class II alloantigens. At the completion of alloantigen injection the Buffalo recipient rats were given 1 ml of ALS intraperitoneally. Twenty-one days later a heterotopic Lewis heart was transplanted. RESULTS: The intrathymic injection of the fractions of Lewis MHC class I and class II expressing B lymphocytes, macrophages, and dendritic cells induced a donor-specific tolerance that resulted in indefinite Lewis cardiac allograft survival (MST > 125 days) in all recipients without further immunosuppression, whereas groups receiving MHC class I expressing red blood cell or T lymphocyte injections plus ALS rejected Lewis cardiac allografts with a MST of 7.3 and 16.5 days, respectively, thus indicating that the MHC class II expressing cell is necessary for the induction of intrathymic tolerance. Buffalo recipients with a long-term surviving Lewis cardiac allograft, after Lewis MHC class II expressing cells were still able to reject a third-party heterotopic ACI (RT1a) cardiac allograft in normal time (MST = 7.0 days), but did not reject a second Lewis cardiac allograft (MST > 100 days). Additionally, the intrathymic injection of MHC class II expressing cells resulted in decreased interleukin-2 (IL-2) production and an 80% decrease in in vitro donor-specific cell mediated cytotoxicity, whereas the cytolytic response to a third party was unaltered. CONCLUSION: Donor MHC class II, and not class I, expressing cells are the cells in donor splenocytes, injected intrathymically, responsible for the development of donor-specific allograft tolerance.

Animals↗
PubMed1993

Induction of donor-specific tolerance to cardiac but not skin or renal allografts by intrathymic injection of splenocyte alloantigen.

We have recently found that donor-specific tolerance to a cardiac allograft can be achieved after the intrathymic (i.t.) injection of donor splenocytes and a single intraperitoneal injection of rabbit antirat lymphocyte serum. The present study evaluated whether the tolerance induced by splenocytes injected i.t. could also prevent the rejection of kidney and skin allografts. Male Buffalo (RT1b) rats were given 25 x 10(6) fully MHC-mismatched unfractionated Lewis (RT1l) splenocytes by i.t. injection plus 1 ml of ALS i.p. and 21 days later underwent a Lewis heterotopic cardiac, orthotopic renal, or skin transplant. Lewis i.t. injection induced a donor-specific tolerance with indefinite cardiac allograft survival (> 153.1 days) in 88% of the recipients without the need for further immunosuppression, while renal and skin allograft survival was prolonged (kidney 14.8 days vs. control 7.8 days; skin 11.6 days vs. control 9.2 days) but were still rejected. Buffalo recipients with a long-surviving Lewis cardiac allograft after Lewis i.t. injection were still able to reject a third-party heterotopic ACI (RT1a) cardiac allograft in normal time (7.0 days), but did not reject a second Lewis cardiac allograft (> 100.0 days). In contrast, however, Buffalo recipients with long-surviving Lewis cardiac allografts did reject a Lewis skin allograft in normal time (10.0 days) and a Lewis renal allograft in a prolonged manner (17.6 days) without causing the rejection of the Lewis cardiac allografts. These data support the important role tissue-specific non-MHC antigens may play in the rejection of kidney and skin allografts.

Animals↗
PubMed1993

Lymphocyte suppression by Kupffer cells prevents portal venous tolerance induction: a study of macrophage function after intravenous gadolinium.

Ag administration into the portal vein can induce specific tolerance to that Ag, known as portal venous tolerance. Because intrahepatic mechanisms of tolerance induction are still largely undefined, we studied the in vitro response of OVA-sensitized Lewis rat lymphocytes to OVA presented by normal syngeneic rat Kupffer cells (KC) or KC that had been treated in vivo with gadolinium chloride (GD), a rare earth metal, which prevents the induction of portal venous tolerance. KC (2.5 x 10(4)) were able to present OVA to 5 x 10(5) OVA-sensitized APC-depleted lymphocytes as effectively as could lymph node APC. However, the use of GD-treated KC was associated with a significantly (P < 0.001) impaired response of OVA-sensitized APC-depleted lymphocytes to OVA. Although GD nearly abrogated in vivo phagocytosis of fluorescent latex beads by both KC and adherent splenocytes, expression of the class II MHC molecule (Ia) by KC was only slightly reduced by GD treatment. Unresponsiveness of OVA-sensitized lymphocytes to OVA was not related to enhanced PGE2 release by GD-treated KC, as determined both by PGE2 levels in culture supernatants and by cyclooxygenase inhibition. However, the marked ability of GD-treated KC to inhibit the response to OVA by primed lymph node populations containing lymphocytes and APCs supports an active suppressive mechanism. Prevention of the induction of portal venous tolerance by GD, the lack of in vitro KC Ag presentation by GD-treated KC, and active immunosuppression by GD-treated KC support a model of tolerance induction within the liver wherein Ag presentation and lymphocyte proliferation are necessary for the development of tolerance.

Animals↗
PubMed1993

Intrathymic injection of donor alloantigens induces specific tolerance to cardiac allografts.

The induction of donor-specific tolerance would eliminate the risk of long-term immunosuppression while ensuring allograft function and survival. Male Buffalo (RT1b) rats were exposed to donor alloantigen by an intrathymic, intrasplenic, s.c., or i.v. injection of 25 x 10(6) syngeneic Buffalo (RT1b) or MHC fully mismatched Lewis (RT1l), ACI (RT1a), or UV-B irradiated Lewis (RT1l) splenocytes. The Buffalo recipients were given 1 cc of rabbit antirat antilymphocyte serum (ALS) i.p. at the time of the donor antigen injection, and 21 days later received a heterotopic Lewis or ACI heart transplant. Only intrathymic alloantigen injection induced a donor-specific tolerance which allowed the cardiac allograft to survive indefinitely (mean survival time [MST] > 176.8 days) in > 86% of the recipients without the need for further immunosuppression, whereas groups receiving antigen injections at other sites rejected cardiac allografts in control time (MST approximately 7.0 days). Histologic examination of long-term tolerated Lewis cardiac allografts revealed the presence of healthy cardiac myocytes without mononuclear infiltration. Buffalo rats with a long-term surviving Lewis cardiac allograft did not reject a second Lewis cardiac allograft (MST > 100.0 days), but rejected a heterotopic ACI cardiac allograft in normal time (MST approximately 7.0 days). By limiting dilution analysis (LDA), maturation of donor-specific CTLs (pCTL) from long-term recipient splenocytes was markedly diminished, whereas third party pCTL was not altered, and T helper-precursors were moderately decreased without alteration in the peripheral CD4+ and CD8+ phenotype frequencies. MLC responses of recipients with long-term surviving cardiac allografts to donor-specific and third party stimulation were not significantly different from naive controls. Microchimerism is unlikely because Lewis allograft survival was also prolonged (MST > 96.0 days) in rats receiving UV-B irradiated Lewis splenocytes which cannot proliferate. The absence of increased allograft survival after transfer of long-term recipient splenocytes into naive animals suggests that donor-specific suppressor cells are not present. Additionally, in vitro lymphocyte proliferative responses to mitogenic or allogeneic stimulation in MLC was not diminished by the addition of these long-term recipient splenocytes. This model emphasizes the importance of exposure of T cell precursors to foreign donor alloantigen in the thymic environment for the development of unresponsiveness to a donor-specific vascularized allograft.

Animals↗
PubMed1993

Development of autoantibodies to T cell clonotypic structures in a liver-kidney allograft recipient.

To elucidate the mechanism of human liver allograft rejection and acceptance, T cell clones were established from liver biopsies of a liver-kidney transplant recipient during a rejection episode. Five of the clones were characterized and found to be CD4+, alpha/beta positive T cells that proliferated specifically to the mismatched donor HLAs. Using an immunofluorescence assay, it was observed that three of these clones were recognized by autologous antibodies developed during the post-transplant period between 18 months and the end of the testing period of 36 months. Furthermore, by capping experiments, it was determined that these antibodies were recognizing the CD3-TCR complex. This was confirmed by immunoprecipitation and sequential immunoprecipitation followed by SDS-PAGE and autoradiography of lysates of radiolabeled T cell clones. Thus, our data indicate that donor-reactive T cells infiltrate into the liver allograft during rejection episodes, and that autologous antibodies reactive to the CD3-TCR complex of these cells are developed in the post-transplant period. These results support the hypothesis that the development of auto-antibodies directed against or cross-reactive to the clonotypic structures of the donor-reactive lymphocytes may play an important role in the down-regulation of the immune response against the allograft.

Autoantibodies↗
PubMed1993

Modulation of the kinetics of the initial leukocyte migration into renal allografts by 16,16-dimethyl PGE2.

Host sensitization to vascular allografts is induced by the interaction between host lymphocytes, antigen-presenting cells, and the allograft. However, little is known concerning the nature or kinetics of the initial host leukocyte migration into the transplanted organ prior to immune sensitization. Employing a model of donor-irradiated renal allografts and isografts, we have characterized the participating cell types and the kinetics of the leukocyte influx during the first 96 hr after engraftment. Both isografts and allografts experience a marked initial influx of host leukocytes into the renal interstitium, peaking at 48 hr after transplantation. Concomitant glomerular accumulation of leukocytes is much less marked. By 96 hr, the leukocyte influx into isografts has significantly diminished, while allografts demonstrate a subsequent additional rise in interstitial leukocytes coincident with the development of allosensitization. In allografts, the predominant cell type in the influx of the first 24-48 hr of the leukocyte influx is the monocyte/macrophage, with a smaller component of T lymphocytes. Neutrophils and B lymphocytes are not found in this initial infiltrate. Intragraft infusion of dimethyl PGE2 markedly inhibits the monocyte influx during the first 24-48 hr into the renal interstitium, but not the glomeruli, of allografts, while having relatively little effect on the migration of leukocytes into the renal glomerulus or renal interstitium of isografts. The results suggest that one mechanism by which PGE may inhibit host sensitization to allografts may be suppression of the initial influx of donor monocytes into the newly allografted organ.

16,16-Dimethylprostaglandin E2↗
PubMed1993

Prostaglandin E2 downregulates Kupffer cell production of IL-1 and IL-6 during hepatic regeneration.

The mammalian liver possesses the ability to regenerate to its original size after a 70% partial hepatectomy (PHx). The capacity of rat Kupffer cells (KC) isolated at specific intervals after PHx to produce interleukin (IL)-1, IL-6, and prostaglandin E2 (PGE2) in response to endotoxin [lipopolysaccharide (LPS)] stimulation was evaluated in standard RPMI 1640 (1,200 microM L-arginine) and arginine-depleted RPMI 1640 (< 10 microM L-arginine) media. Because KC function in an environment in which high arginase activity results in negligible L-arginine levels, the 10 microM L-arginine RPMI 1640 was used to simulate the hepatic microenvironment. Regenerating liver KC 12-120 h after PHx responded to LPS with a significantly greater (P < 0.05) production of IL-1 and IL-6 in standard RPMI 1640. This enhancement of regenerating liver KC to produce IL-1 and IL-6 was increased (P < 0.05) by placing these same KC in 10 microM arginine RPMI 1640 culture media. During the same time period, regenerating liver KC produced significantly elevated (P < 0.01) PGE2, again with greater differences in the low-arginine media. In vivo KC PGE2 blockade by indomethacin (5 mg/kg) significantly (P < 0.05) inhibited hepatic regeneration. When the cyclooxygenase inhibitor indomethacin (10 microM) was added to cultures, the production of PGE2 by KC was prevented, and in arginine-depleted cultures, IL-1 and IL-6 production was upregulated (P < 0.05). We conclude that during hepatic regeneration, KC IL-1 and IL-6 production is elevated and is controlled in an autoregulatory fashion by elevated KC PGE2 production.

Animals↗
PubMed1993

Prevention by thymectomy of tolerance induced by intrathymic injection of donor splenocytes.

BACKGROUND: We have recently demonstrated indefinite donor-specific cardiac allograft survival after the intrathymic injection of donor splenocytes and simultaneous injection of antilymphocyte serum (ALS) in a fully major histocompatibility complex-mismatched rat combination. In this study we performed thymectomy to determine the length of time required for donor alloantigen to be present in the recipient thymus to induce tolerance. METHODS: Male Buffalo (BUF; RT1b) rats at 4 to 8 weeks of age underwent intrathymic injection of 25 x 10(6) Lewis (LEW; RT1(1)) splenocytes and simultaneously received an intraperitoneal injection of 1 ml ALS. To determine the kinetics of tolerance induction, the BUF recipients underwent thymectomy on days 1, 3, or 7 after the initial intrathymic injection of alloantigen and intraperitoneal ALS. Twenty-one days after intrathymic alloantigen injection and ALS, all rats underwent transplantation with a heterotopic LEW cardiac allograft. RESULTS: Thymectomy performed 1 (mean survival time, 6.8 days) and 3 (mean survival time, 8.0 days) days after donor alloantigen injection and ALS did not affect the normal rejection of LEW cardiac allografts. In contrast, thymectomy 7 days after intrathymic alloantigen injection and ALS resulted in indefinite survival of cardiac allografts in 75% of recipients (mean survival time > 77.0 days). In addition, allospecific cytotoxic T lymphocyte activity and interleukin-2 production were markedly decreased in those recipients undergoing thymectomy after 7 days compared with untreated control rats and recipients undergoing thymectomy 1 and 3 days after alloantigen injection. CONCLUSIONS: The presence of the thymus for at least 7 days after intrathymic alloantigen injection and intraperitoneal ALS allows the development of indefinite donor-specific cardiac allograft tolerance.

Animals↗
PubMed1993

Closure of complex abdominal wall defects with bilateral rectus femoris flaps with fascial extensions.

Large full-thickness abdominal wall defects present a difficult reconstructive problem. Synthetic mesh has significant drawbacks and should be used only as a temporizing measure. Ideally abdominal wall defects should be resurfaced with well-vascularized autologous fascia and skin. A variety of myofascial, myocutaneous, and myofasciocutaneous flaps have been described. This report describes two cases of near-total abdominal wall reconstruction using bilateral rectus femoris myocutaneous flaps with fasciocutaneous extensions of superficial thigh fascia and skin. In both cases the rectus femoris flaps and fascial extensions healed, and the patients went on to full recovery. In one patient the skin over the fascial extension did not survive and had to be debrided and the underlying vascularized fascia resurfaced with a skin graft. The extended rectus femoris flap is a reliable and versatile flap that leaves negligible functional deficits. The fascial extensions are reliable and well perfused and should be included in the reconstruction of larger abdominal wall defects. The skin overlying the fascial extensions is less reliable, and selective use is recommended.

Abdominal Muscles↗
PubMed1992

Changes in bilirubin pigments secreted in bile after liver transplantation.

The species of bile pigments secreted in T-tube fistula bile after liver transplantation were ascertained by high-performance liquid chromatography in 15 patients for 10 days after liver transplant. Nine glycosidic conjugates and unconjugated bilirubin were resolved by the analytical procedure. The principal pigments in bile and their proportions in normal patients were the following: bilirubin diglucuronide = 83.0% +/- 3.1% (S.D.); bilirubin monoglucuronide = 9.7% +/- 1.4% (S.D.); bilirubin monoglucuronide monoglucoside = 4.0% +/- 2.8% (S.D.); and bilirubin monoglucuronide monoxyloside = 1.5% +/- 1.8% (S.D.). All of the other possible glucuronide, glucose and xylose monoconjugates and diconjugates and unconjugated bilirubin were also found, but each was normally less than 1% of the total. In 13 of the 15 transplant patients, a significant depression in proportions of bilirubin diglucuronide and elevation in proportions of bilirubin monoglucuronide were found after the transplant, with an accompanying but generally small increase in the proportions of the minor conjugates. In two patients with rejection of the transplant, the changes were of larger magnitude, with improvement occurring only with recovery from the rejection. In one of these patients, kidney failure was present, and in addition to the diglucuronide and monoglucuronide conjugates, diglucoside and monoglucoside monoxyloside conjugates were found in plasma. The underlying metabolic abnormalities are not clear but likely reflect underlying abnormal intracellular cofactor levels for conjugation. Glycogen depletion with reduction of UDP-glucuronate levels or reduced UDP-glucuronate formation from UDP-glucose, secondary to elevation of UDP-xylose, could potentially account for the changes in pigment excretion.

Adult↗
PubMed1992

Kupffer cell autoregulation of IL-1 production by PGE2 during hepatic regeneration.

The mammalian liver possesses the ability to regenerate to its original size after a 70% partial hepatectomy (PHx). The capacity of rat Kupffer cells (KC) isolated at specific intervals following PHx to produce interleukin-1 (IL-1) and prostaglandin E2 (PGE2) in response to endotoxin (LPS) was evaluated in standard RPMI-1640 (1200 microM L-arginine) and arginine-depleted RPMI-1640 (10 microM L-arginine) media. Regenerating liver KC 48-120 hr following PHx responded to LPS with a significantly greater (p less than 0.05) production of IL-1 in standard RPMI-1640. When 10 microM L-arginine RPMI-1640 was used to simulate the high arginase activity low L-arginine levels of the hepatic microenvironment, regenerating liver KC production of IL-1 was further increased (p less than 0.05). During the same time period, regenerating liver KC also produced significantly (p less than 0.01) more PGE2 than sham KC in both high and low arginine media. When the cyclooxygenase inhibitor indomethacin (10 microM) was added to low arginine cultures, the PGE2 production was inhibited, and IL-1 production was upregulated (p less than 0.05). We conclude that during hepatic regeneration KC IL-1 production is elevated but controlled in an autoregulatory fashion by KC PGE2 production.

Animals↗
PubMed1992

Intrathymic injection of donor alloantigens induces donor-specific vascularized allograft tolerance without immunosuppression.

The induction of donor-specific tolerance could prevent the side effects of immunosuppression while improving allograft survival. Male adult Buffalo (RT1b) rats underwent an intrathymic (IT), portal venous (PV), intrasplenic (IS), or subcutaneous (SQ) injection of 25 x 10(6) major histocompatibility complex (MHC) mismatched Lewis (RT1(1)), UV-B-irradiated Lewis (RT1(1)), ACI (RT1a), or syngeneic Buffalo (RT1b) splenocytes. At the completion of the donor alloantigen injection, 1 mL rabbit anti-rat lymphocyte serum (ALS) was administered intraperitoneally to the Buffalo recipients, and 21 days later a heterotopic Lewis or ACI heart was transplanted. Intrathymic injection of donor alloantigen induced a donor-specific tolerance that allowed the cardiac allograft to survive indefinitely (mean survival time [MST] > 140.7 days) in 84% of the recipients without further immunosuppression, whereas groups receiving antigen injections at other sites (PV, IS, and SQ) plus ALS rejected cardiac allografts in normal fashion (MST approximately 8.0 days). Buffalo recipient rats with long-term surviving Lewis cardiac allografts after Lewis IT injection and ALS subsequently rejected a heterotopic third-party ACI cardiac allograft in normal fashion (MST approximately 7 days), whereas a second Lewis cardiac allograft was not rejected (MST > 116 days). Microchimerism is unlikely because Lewis allograft survival was also prolonged (MST > 38.7 days) in rats receiving UV-B-irradiated splenocytes IT, which cannot proliferate. Survival of Lewis renal allografts was also prolonged, but not indefinitely, in Buffalo recipients possessing a long-term surviving Lewis cardiac allograft (MST approximately 17.6 days versus 7 days for control). This model emphasizes the potential role of exposure of immature thymocytes to foreign donor alloantigens during maturation in the thymic environment for the development of unresponsiveness to an MHC-mismatched donor-specific vascularized allograft.

Animals↗
PubMed1992

A polymorphic human kidney-specific non-MHC alloantigen. Its possible role in tissue-specific allograft immunity.

Tissue specific non-MHC alloantigens play a crucial role in allograft immunity. However, their structural properties have remained elusive, largely due to their inability to induce a strong antibody response. We report the characterization of a monkey heteroantiserum, MHK-I, raised against human kidney cells, that serologically reacts specifically with kidney cells after extensive absorptions of anti-HLA class I and II reactivities. The non-MHC MHK-I-binding molecule(s) is expressed only in the renal cortex on the glomerulus, peritubular capillaries, venous endothelium, and tubular epithelium. Immunochemically, MHK-I recognizes a kidney-specific non-MHC alloantigen of Mr 90,000 to 100,000 (90 kD). These properties of MHK-I are similar to those of the previously characterized alloantibodies eluted from rejected kidneys. These alloantibodies bind to the kidney from which the antibody was eluted and to a few others but are unlike MHK-I, which binds to extracts prepared from all human kidneys. Biochemical analysis by two-dimensional electrophoresis (pI ranging between 4.5 and 5.5) and peptide fingerprinting provide further evidence that the alloantigen is polymorphic. These findings imply that the non-MHC kidney-specific molecule(s) may function as target(s) for immune destruction of renal allografts.

Animals↗