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Biomedical subjects

B M Hall

Publications and source records attributed to B M Hall.

At least 19 recordsLinked to original sources
PubMed1999

Induction of specific tolerance to allografts in rats by therapy with non-mitogenic, non-depleting anti-CD3 monoclonal antibody: association with TH2 cytokines not anergy.

BACKGROUND: Anti-CD3 monoclonal antibodies (mAb) are potent immunosuppressives in transplantation but most do not induce tolerance. They induce anergy in Th1 cells but, if they bind to Fc receptors on antigen presenting cells, they activate T cells to release cytokines. METHODS: This study examined the mechanisms of transplant tolerance induction to PVG fully allogeneic grafts in dark agouti rats by G4.18, a mouse immunoglobulinG3 anti-rat CD3 mAb that does not bind rat Fc receptors. Evidence of T cell activation was assayed by flow cytometry, reverse transcription (RT)-polymerase chain reaction (PCR) for cytokine mRNA, and responsiveness in mixed lymphocyte culture. RESULTS: G4.18 treatment modulated T cell receptor/CD3 and CD2 and depleted T cells by <20% but did not induce activation surface markers. mRNA for interleukin (IL)-2, interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, and IL-4 in the lymph node, spleen, and thymus was not increased, and IFN-gamma mRNA was reduced. G4.18-treated and naive rat cells had similar proliferation and expression of IL-2, IFN-gamma, and IL-4 in vitro. G4.18-treated allograft recipients had no induction of mRNA for IL-2, IFN-gamma, TNF-alpha, TNF-beta, IL-4, IL-5, IL-10, perforin, and granzyme A & B in the spleen or grafts, with levels similar to those in isografts. The IL-4 and IL-5 mRNA levels in the spleen but not the graft of G4.18-treated recipients were higher than in rejecting and naive animals. Cells from G4.18-treated graft recipients proliferated more rapidly to the donor than to the third party and had increased IL-4 expression. CONCLUSIONS: G4.18 induced transplant tolerance by a combination of modulation and blocking of the TCR/CD3, associated with increased Th2 cytokines, without depletion, induction of anergy, or nonspecific activation of T cells.

Animals↗
PubMed1998

Permanent CD8(+) T cell depletion prevents proteinuria in active Heymann nephritis.

Active Heymann nephritis (HN) is a rat model of human idiopathic membranous nephropathy in which injury is thought to be mediated by membrane attack complex of complement (MAC) activated by antibody (Ab) to glomerular epithelial cells. Recent work has shown that HN develops in C6-deficient rats which cannot assemble MAC, and that infiltration of activated cytotoxic CD8(+) T cells and macrophages into glomeruli coincides with proteinuria. This study examined the role of CD8(+) T cells in mediating glomerular injury in HN by permanent CD8(+) cytotoxic T cell depletion via adult thymectomy (ATx) and anti-CD8 mAb. Groups of rats were depleted of CD8(+) T cells either before immunization for HN or 6 wk after immunization when Ab responses and glomerular IgG deposition were well established. These were compared with groups of HN, ATx/HN, and complete Freund's adjuvant (CFA) controls. Neither group of CD8(+) T cell-depleted rats developed proteinuria, although there was normal development and deposition of Ab. CD8(+) T cell-depleted rats developed neither T cell or macrophage infiltrates nor their effector cytokines, which are present in glomeruli of rats with HN. Examination of lymph node (LN) draining sites of immunization showed these findings were not explained by altered immune events within these LNs. It was concluded that CD8(+) cytotoxic T cells are essential to the mediation of glomerular injury in HN and may be relevant to the pathogenesis and treatment of membranous nephropathy.

Animals↗
PubMed1998

Anti-CD4 monoclonal antibody-induced tolerance to MHC-incompatible cardiac allografts maintained by CD4+ suppressor T cells that are not dependent upon IL-4.

Anti-CD4 mAb-induced tolerance to transplanted tissues has been proposed as due to down-regulation of Thl cells by preferential induction of Th2 cytokines, especially IL-4. This study examined the role of CD4+ cells and cytokines in tolerance to fully allogeneic PVG strain heterotopic cardiac allografts induced in naive DA rats by treatment with MRC Ox38, a nondepleting anti-CD4 mAb. All grafts survived >100 days but had a minor mononuclear cell infiltrate that increased mRNA for the Thl cytokines IL-2, IFN-gamma, and TNF-beta, but not for Th2 cytokines IL-4 and IL-6 or the cytolytic molecules perforin and granzyme A. These hosts accepted PVG skin grafts but rejected third-party grafts, which were not blocked by anti-IL-4 mAb. Cells from these tolerant hosts proliferated in MLC and produced IL-2, IFN-gamma, and IL-4 at levels equivalent to naive cells. Unfractionated and CD4+ T cells, but not CD8+ T cells, transferred specific tolerance to irradiated heart grafted hosts and inhibited reconstitution of rejection by cotransferred naive cells. This transfer of tolerance was associated with normal induction of IL-2 and delayed induction of IFN-gamma, but not with increased IL-4 or IL-10 mRNA. Transfer of tolerance was also not inhibited by anti-IL-4 mAb. This study demonstrated that tolerance induced by a nondepleting anti-CD4 mAb is maintained by a CD4+ suppressor T cell that is not associated with preferential induction of Th2 cytokines or the need for IL-4; nor is it associated with an inability to induce Th1 cytokines or anergy.

Adoptive Transfer↗
PubMed1998

Treatment with interleukin-4 prolongs allogeneic neonatal heart graft survival by inducing T helper 2 responses.

BACKGROUND: The T helper (Th) 2 cytokine interleukin (IL)-4 has been implicated as a major regulatory cytokine for the induction of transplant tolerance, but few studies have examined the capacity of IL-4 to induce tolerance. The effect of IL-4 therapy alone or with low doses of anti-CD4 monoclonal antibody (mAb) therapy on survival of fully allogeneic PVG neonatal heart graft in adult DA rats was examined. METHODS: Rat recombinant (r) IL-4 was given at 30 microg (10(4) U)/kg daily intraperitoneally for 10 days and MRC OX35 (anti-CD4, nondepleting) or MRC OX81 (anti-IL-4) was given intraperitoneally on days 0, 3, 7, and 10. Semiquantitative reverse transcriptase-polymerase chain reaction was used to assay mRNA for cytokine in the graft, regional node and spleen and fluorescence-activated cell sorting was used to assay alloantibody Ig isotypes. RESULTS: Grafts in rIL-4-treated rats survived a median period of 39 days (range, 28-52 days), significantly longer than in both untreated and nontransfected Chinese hamster ovary-K1 supernatant-treated controls (median, 14 days; range, 10-16 days, P=0.009). rIL-4 treatment with a suboptimal dose of anti-CD4 mAb prolonged median survival to 70 days (range, 63-80 days), which was longer than rIL-4 treatment alone or anti-CD4 mAb alone (median, 36 days; range, 30-55 days; P<0.0045). Combining MRC OX81 with MRC OX35 therapy led to earlier rejection at a median period of 26 days (range, 20-28 days); MRC OX81 alone had no effect on graft survival. Alloantibody titers, especially IgG1, were higher in rIL-4-treated animals and lower in anti-CD4 mAb-treated animals than in animals with normal rejection (P<0.05). IL-4 mRNA was increased in regional lymph nodes and spleen of the rIL-4-treated groups compared with all other groups, but there were no differences for IL-2, interferon-gamma, or IL-10. CONCLUSIONS: rIL-4 therapy markedly prolonged neonatal cardiac allograft survival, and, with anti-CD4 therapy, it further prolonged survival. It induced IL-4 mRNA in lymphoid tissues and enhanced alloantibody production, especially IgG1, which demonstrated enhanced Th2 responses, but did not affect Th1 cytokines.

Animals↗
PubMed1998

The cellular basis of cardiac allograft rejection: VIII. Mechanisms underlying delayed allograft rejection in PVG C6-deficient rats.

BACKGROUND: The delayed allograft rejection in C6-deficient PVG C6- rats compared with normal PVG rats has been attributed to the lack of alloantibody activation of the membrane attack complex of complement. As T cells alone have been shown to effect graft rejection, we examined T-cell responses in PVG C6- rats. METHODS: The cellular infiltrate and its mRNA for cytokines and effector molecules in DA heart allografts to PVG and PVG C6- rats was compared by immunoperoxidase staining and semiquantitative reverse transcriptase polymerase chain reaction. The ability of pure populations of T cells or alloantibody to mediate DA heart graft rejection in irradiated (750 rads) PVG and PVG C6- rats was also compared. RESULTS: The median rejection time of DA heart allografts was 8 days in PVG rats and 17.5 days in PVG C6-. PVG C6- rats sensitized to DA by two skin grafts rejected DA heart grafts in 5-6 days. CD3+, CD4+, CD8+, interleukin-2 receptor-positive T cell, macrophage, and natural killer cell infiltration, as well as class II major histocompatibility complex and intercellular adhesion molecule-1 up-regulation, in grafts was similar in naive PVG and PVG C6- rats. mRNA for T helper 1 cytokine interleukin-2, interferon-gamma, tumor necrosis factor-beta, macrophage molecules tumor necrosis factor-alpha, and inducible nitric oxide synthase, as well as cytotoxic T-cell effector molecules perforin and granzyme A and B, were found to be the same in the grafts from both naive PVG and naive PVG C6- rats. Thus, there appeared to be no difference in the T-cell effector response between the PVG and PVG C6- groups. There were higher alloantibody titers in PVG C6- rats than in PVG hosts. Irradiation ablated rejection and alloantibody responses and reconstitution with naive T cells alone restored rejection in both PVG and PVG C6- rats. Irradiated rats given serum from PVG rats that had rejected DA grafts did not effect rejection of DA grafts even if given naive T cells. Sensitized T cells restored second set. CONCLUSIONS: PVG C6- rats have normal T-cell responses and can mediate allograft rejection in the absence of alloantibody. The failure of PVG C6- to reject allografts rapidly may be a result of the poor clearance of alloantisera leading to enhancement of graft survival rather than a critical role for complement and membrane attack complex in acute rejection.

Animals↗
PubMed1998

Mycophenolate mofetil prevents the induction of active Heymann nephritis: association with Th2 cytokine inhibition.

The effect of mycophenolate mofetil (MMF) was examined in active Heymann nephritis (HN), an animal model of human membranous nephropathy. HN was induced in Lewis rats with Fx1A/complete Freund's adjuvant (CFA), and controls only received CFA. The induction of HN was prevented by MMF (30 mg/kg per d) from 0 to 4 wk after immunization. Proteinuria was not different in CFA controls up to 16 wk, and was significantly less than in untreated HN from 6 wk onward. Serum anti-Fx1A antibody (Ab) levels and glomerular Ig deposition were suppressed during therapy. The interstitial infiltrate of alphabetaTCR+, CD4+ and CD8+ T cells, natural killer cells, and macrophages (mphi) observed in untreated HN at 8 wk was absent from rats treated from 0 to 4 wk with MMF. Semiquantitative reverse transcription-PCR for renal mononuclear cell cytokine mRNA at 8 wk demonstrated that MMF from 0 to 4 wk prevented the increased expression of Th1 (interferon-gamma, lymphotoxin), Th2 (interleukin-4), and mphi (tumor necrosis factor-alpha) cytokines identified in untreated HN. In lymph node draining sites of immunization, MMF limited both enlargement and the increased proportion of CD3+, CD4+, and CD8+ T cells observed in untreated HN and CFA controls. MMF suppressed Th2 (interleukin-4) but not Th1 (interferon-gamma, lymphotoxin) cytokine mRNA expression in lymph nodes. MMF from 4 to 8, 6 to 12, or 10 to 14 wk did not prevent proteinuria, serum anti-Fx1A Ab, or glomerular IgG deposition when compared with untreated HN. This study showed that MMF from 0 to 4 wk prevented the induction of HN and was associated with preferential suppression of Th2 cytokines. This therapy may prove useful in human idiopathic membranous nephropathy.

Animals↗
PubMed1997

Induction of tolerance with nondepleting anti-CD4 monoclonal antibodies is associated with down-regulation of TH2 cytokines.

BACKGROUND: Induction of tolerance with anti-CD4 has mainly focused on monoclonal antibodies (mAbs) that deplete CD4+ T cells. In this study, the mechanisms by which nondepleting anti-CD4 mAbs induce tolerance in the Dark Agouti to PVG rat heart graft model were examined. METHODS: Five anti-CD4 mAbs were tested. Immunohistology and cytokine mRNA profiles were analyzed within grafts. Effects of combining anti-CD4 therapy with alloantibody (alloAb), interleukin (IL)-4, and anti-IL-4 mAb were also examined. RESULTS: All mAbs tested induced indefinite graft survival (>150 days), with blocking of alloAb production. Exogenous alloAb did not restore rejection. Similar T cell receptor alphabeta+, CD8+, IL-2 receptor+ T cell, macrophage, and natural killer cell infiltration and comparable MHC II and intercellular adhesion molecule-1 levels were seen in rejecting and tolerant grafts. mRNA for IL-2, interferon-gamma, lymphotoxin, tumor necrosis factor-alpha, transforming growth factor-beta, cytolysin, and granzyme-A/B was comparable, although inducible nitric oxide synthase was slightly reduced in tolerant grafts. IL-4 and IL-5 were significantly reduced in tolerant grafts, although IL-6, IL-10, and IL-13 levels were similar; this was consistent with partial T helper (Th)2 response inhibition, which was also manifested by inhibited alloAb. The combination of alloAb, IL-4, or anti-IL-4 mAb with anti-CD4 did not prevent tolerance induction. CONCLUSIONS: This study demonstrated that anti-CD4 mAb therapy did not inhibit activation and infiltration of Th1 and CD8+ effector T cells. Preferential induction of Th2 responses, especially IL-4, was not essential for the induction of tolerance. Our studies also found no evidence to support induction of anergy or transforming growth factor-beta as mechanisms of tolerance induction. These results question whether IL-4 is required for induction of transplantation tolerance.

Animals↗
PubMed1997

Role of T cells in the mediation of Heymann nephritis. ii. Identification of Th1 and cytotoxic cells in glomeruli.

The role of immunoglobulin (Ig) and complement as mediators of Heymann nephritis (HN) has been questioned by recent studies showing that HN can be induced in a C6-deficient rat that cannot assemble the membrane attack complex of complement. Also, the severity of HN can be reduced by therapy directed at CD8+ T cells, which has no effect on antibody (Ab) production or immune deposits. To identify whether T cells may contribute to the glomerular injury of active HN in Lewis rats, the mononuclear infiltrate and cytokine mRNA in glomeruli and kidney interstitium were examined. Groups of Lewis rats immunized with Fx1A in CFA developed HN, and were compared to controls that received CFA only. Proteinuria, the marker of glomerular filtration barrier dysfunction, was absent at four weeks but present at eight weeks in HN. Serum anti-Fx1A Ab and glomerular Ig were present in HN at both time points. Immunoperoxidase staining with monoclonal Abs identified, at eight weeks, a glomerular infiltrate of CD4+ and CD8+ T cells, and macrophages, but not NK cells. Semiquantitative RT-PCR of isolated glomeruli at eight weeks demonstrated expression of cytokine mRNA for Th1 CD4+ cells (IFN-gamma and TNF-beta/LT, but not IL-2), cytotoxic CD8+ T cells (granzyme A and perforin), and macrophages (TNF-alpha and IL-10), but not Th2 CD4+ cells (no increase in IL-4, IL-5 and IL-6). At eight weeks, the cellular infiltrate and pattern of cellular activation in glomeruli was different to that in renal cortex. In the cortical infiltrate CD8+ cells were a lesser component, and NK cells were increased, as were CD4+ cells and macrophages. RT-PCR identified increased cytokine mRNA for macrophages, Th1 and Th2 cells, but not cytotoxic effector T cells. At four weeks, T cells including CD4+ and CD8+ cells were identified in the isolated glomeruli of rats with HN, but there was no increase in cytokine mRNA expression. There was no infiltrate or increase in cytokine mRNA detected in renal cortex at four weeks. Anti-Fx1A Ab's and glomerular deposition of Ig develop many weeks before the onset of proteinuria, when there is only a small cellular infiltrate present. The progressive development of infiltrates of activated T cells, principally Th1 and cytotoxic effector cells, and macrophages, within glomeruli is coincident with the development of proteinuria. These findings raise the possibility that these cells contribute to the mediation of the glomerular injury and proteinuria of HN.

Animals↗
PubMed1997

Threshold for occluded formaldehyde patch test in formaldehyde-sensitive patients. Relationship to repeated open application test with a product containing formaldehyde releaser.

Our purpose was to investigate the eliciting threshold concentration of formaldehyde in formaldehyde-sensitive individuals in the occluded and non-occluded patch test, and to evaluate the relationship to repeated open application test (ROAT) with a product containing a formaldehyde releaser. 20 formaldehyde-sensitive patients and a control group of 20 healthy volunteers were included in the study. Occluded and non-occluded patch tests with formaldehyde solutions from 25 to 10,000 ppm, and ROAT for 1 week with a leave-on cosmetic product containing on average 300 ppm formaldehyde, were carried out simultaneously on each subject. In the occluded patch test, 1/2 of the 20 patients only reacted to 10,000 ppm formaldehyde, 9 reacted to 5,000 ppm, 3 reacted to 1,000 ppm, 2 reacted to 500 ppm and 1 reacted to 250 ppm. No definite positive reactions were observed in the non-occluded patch test or in the ROAT. No positive reactions were observed in the control group to any of the test procedures. We concluded that the threshold concentration for occluded patch test to formaldehyde in formaldehyde-sensitive patients was 250 ppm. The threshold in occluded patch test corresponded to the degree of sensitivity. Definite positive reactions in the ROAT were not seen, either indicating that they are unlikely to happen with the type of product used or that the exposure time was too short.

Adult↗
PubMed1995

Cardiac allograft vascular disease. Relationship to microvascular cell surface markers and inflammatory cell phenotypes on endomyocardial biopsy.

BACKGROUND: Cardiac allograft vascular disease is characterized by accelerated and diffuse intimal proliferation involving both the microvasculature and epicardial vessels. Because in vivo documentation of this complication is now possible with intracoronary ultrasound imaging, we can examine the relationship of intimal proliferation to markers of immunity and endothelial activation. We hypothesize that alterations of microvascular cell surface markers likely mirror changes in the epicardial vessels that may be important in the pathophysiology of intimal proliferation. METHODS AND RESULTS: Forty-three heart transplant patients were examined by intracoronary ultrasound more than 1 year after transplantation, and these images were analyzed to obtain mean intimal thickness and intimal thickness class (I through IV), calculated from the mean thickness and circumferential involvement. Right ventricular endomyocardial biopsies obtained at the time of intracoronary ultrasound were examined by immunohistochemistry to detect microvascular expression of histocompatibility leukocyte antigen (HLA) classes I and II (HLA ABC, DR, DP, and DQ); endothelial-specific antigen detected by the monoclonal antibody E 1.5; intercellular adhesion molecules (ICAM-1); CD4+ and CD8+ lymphocytes and macrophages (CD 14+). Microvascular antigen expression was graded 1 through 5 on the basis of the diffuseness of positive staining. The number of each inflammatory cell phenotype present per high-power field was counted. By ANOVA, scores for HLA DR, HLA DQ, and E1.5 expression were lower in intimal thickness classes II, III, and IV compared with class I. This inverse relationship was significant by linear regression analysis of mean intimal thickness. Inflammatory cells were not significantly correlated with intimal thickening. Rejection incidence was higher, and time since transplantation longer, in intimal thickness classes II, III, and IV compared with class I. CONCLUSION: Transplant coronary artery intimal proliferation is associated with alteration of microvascular endothelial cell surface markers. These changes in cell surface antigen expression could provide the substrate for coronary artery intimal proliferation and narrowing.

Adult↗
PubMed1995

Active Heymann nephritis in complement component C6 deficient rats.

The mechanisms of renal injury that result in proteinuria in active Heymann nephritis (AHN) remain unclear, though data suggest that in analogy of the passive form of the disease the membrane attack complex C5b-9 may be involved. AHN was induced in an inbred strain of PVG/c-rats that are totally deficient in the C6 component of complement and are unable to form the lytic C5b-9 complex, as well as in non-complement deficient PVG/c+ rats that are immunologic identical to the deficient strain. In both groups of animals comparably high titers of anti-Fx1A autoantibodies were found after three weeks and persisted at 40 weeks. Proteinuria was also similar in both groups, and was first evident at six weeks. High levels of urinary protein, ranging from 200 mg/24 hr to 500 mg/24 hr, were found after 10 weeks and persisted up to one year. Renal biopsy findings at various times post-immunization were identical in both groups, including immunofluorescence staining for Ig and C3 deposits, and also EM findings of subepithelial electron-dense deposits were not different. The injection of heterologous rabbit complement, that partially and temporarily restored the CH50 activity in PVG/c- rats did not alter or hasten the disease. Long-term follow-up showed that all rats in both groups continued to have severe proteinuria and that most animals died between 8 to 12 months after disease induction, without renal impairment. EM findings in serial biopsies demonstrated that the growth of the subepithelial deposits as measured by surface area occurred between weeks 4 and 12. A positive correlation (r = 0.94) between the size of the deposits and the level of proteinuria was found. These studies demonstrate that the membrane attack complex of complement does not play a major role in AHN. The relationship of the size of the immune deposits to the level of proteinuria suggests that the growth of the immune deposits on itself initiate secondary mechanisms that damage the permselective characteristics of the glomerular membrane.

Animals↗
PubMed1994

A monoclonal antibody (A6) recognizing a unique epitope restricted to CD45RO and RB isoforms of the leukocyte common antigen family identifies functional T cell subsets.

The mAb A6 was produced by immunization of mice with human PHA-stimulated PBMC. Immunoprecipitation studies and staining of cell lines transfected with individual leukocyte common antigen (LCA) isoforms showed that A6 recognizes a unique epitope strongly expressed on the lower MW isoform (p180) of LCA, but also weakly expressed on the p190 isoform coded by exon B and the p205 coded by exons A and B. The epitope recognized by A6 was carbohydrate-dependent in that it was neuraminidase-sensitive, but trypsin-resistant. A6 strained most TCR-alpha beta+ cells with differential intensities, subdividing them into a bright and dim population, and strongly stained all TCR-gamma delta+ cells. A6 did not stain CD19+ B cells nor CD56+ NK cells. Anti-CD45 mAb such as UCHL1 recognizing CD45RO have been used to define memory T cells. Depletion of PBMC subsets with A6 or UCHL1 mAb dramatically decreased proliferative responses to the recall antigens anti-CD3 mAb and alloantigen and enhanced their responses to PHA. A6, unlike UCHL1, also depleted alloreactive T cells that affect primary and secondary MLC and CML. Thus, A6 was shown to recognize the lower MW isoforms of LCA which are expressed on functional T cell subsets including memory, activated, and alloreactive T cells.

Animals↗
PubMed1994

Hereditary C6 deficiency in a strain of PVG/c rats.

A chance observation has led to the discovery of a strain of PVG rats (PVG/c-) which are deficient in complement (C) component C6. Analysis of total haemolytic activity (CH50) of PVG/c- serum revealed an absent CH50 activity compared with serum of other rat strains and of a PVG/c rat (PVG/c+) that showed normal C activity. Thus, the PVG/c- rat was unable to activate the C5b-9 membrane attack complex. To gain insight into the complement abnormalities, analysis of individual C components was performed. Testing the PVG/c- serum in a C6 haemolytic assay and using deficient human sera showed a deficiency of C6 in the PVG/c- rat. Highly purified human C6 and human sera deficient in other components were able to reconstitute the CH50 activity of the PVG/c- rat. The possibility that an inactivator of C was present in PVG/c- serum was excluded. The deficiency was found to be inheritable and under the control of an autosomal recessive gene. Furthermore, tissue antigens and immunity of the PVG/c- rat were found to be identical to those determined in the PVG/c+ rat. With regard to their health status, the PVG/c- animals seem to have no disadvantages compared with PVG/c+ rats when held under the same conditions within the protected environment of animal facilities. Taken together, both rat strains provide an unique animal model for studying the biological role of C, particularly the C5b-9 membrane attack complex in experimental medicine.

Animals↗
PubMed1993

Elevated levels of tumor necrosis factor-alpha in the nephrotic syndrome in humans.

To investigate the possible role of cytokines in the mediation of glomerular injury in the nephrotic syndrome, the levels of interleukin (IL)-1 beta, IL-2, interferon (IFN)-alpha, IFN-gamma, and tumor necrosis factor-alpha (TNF-alpha) were measured in patients with primary nephrotic syndrome. These patients had minimal change nephropathy (MCN), focal and segmental glomerulosclerosis (FSGS), or membranous nephropathy (MN) on biopsy. Cytokine levels were assessed by immunoradiometric assays, and specimens consisted of plasma, urine, and the culture supernate of mitogen-stimulated peripheral blood mononuclear cells (PBMC). Only TNF-alpha was found to be significantly elevated, in the plasma and urine of patients with FSGS and MN, above that found in healthy control subjects and patients with MCN. The elevation of TNF-alpha could not be shown to correlate with the length or severity of the nephrotic syndrome or with loss of body mass. IL-1 beta, IL-2, IFN-alpha, and IFN-gamma levels were not elevated. In culture, mitogen-stimulated PBMC from all three groups of nephrotic subjects released an excess of TNF-alpha compared with controls, a response not consistently observed for the other cytokines measured. The findings of this survey of cytokine levels in nephrotic patients support the possibility that TNF-alpha may play a pathogenic role in the induction or maintenance of glomerular barrier dysfunction in humans.

Adolescent↗
PubMed1993

Specific unresponsiveness in rats with prolonged cardiac allograft survival after treatment with cyclosporine. V. Dependence of CD4+ suppressor cells on the presence of alloantigen and cytokines, including interleukin 2.

CD4+ cells from CsA-treated DA rats with long-surviving PVG heart allografts specifically suppress the capacity of naive CD4+ cells to restore allograft rejection in irradiated DA rats, but have normal donor-specific alloreactivity in MLC. CD4+ suppressor cells from CsA-treated DA rats cultured for 3 days against either PVG or DA spleen cells lost the capacity to transfer suppression into irradiated DA rats grafted with PVG hearts and regained the ability to mediate rejection. However, these cells retained suppressor function when stimulated with donor-specific alloantigen in media supplemented with 20% Con A supernatant. CD4+ cells from CsA-treated rats cultured against either third-party stimulator cells or syngeneic cells expressing anti-PVG idiotype in media supplemented with Con A supernatant failed to maintain suppressor cell function. CD4+ cells from CsA-treated rats cultured in media supplemented with Con A supernatant alone also failed to maintain suppressor function. Suppressor cell function in culture was not maintained by rIL-2. mAb to the IL-2 receptor alpha chain (CD25) prevented the maintenance of suppressor cell function in media supplemented with Con A supernatant. Con A supernatant is rich in IFN-gamma, but addition of an anti-IFN-gamma mAb to the culture did not affect the maintenance of suppressor cells. These studies demonstrate that the CD4+ suppressor cell from CsA-treated rats with long-surviving grafts is short-lived; its survival is dependent upon contact with specific alloantigens and cytokines, one of which is IL-2. In the absence of cytokines and/or specific alloantigen, the CD4+ cells regain the capacity to initiate graft rejection in irradiated rats, suggesting that within the CD4+ subpopulation there is a fragile balance between cells with the capacity to suppress and effect rejection.

Animals↗
PubMed1993

Specific unresponsiveness in rats with prolonged cardiac allograft survival after treatment with cyclosporine. VI. In vitro alloreactivity of T cell subsets from rats with long-surviving allografts.

DA rats treated with a short course of cyclosporine develop specific unresponsiveness to RT1-incompatible PVG donor heart allografts. CD4+ cells, not CD8+ cells, transfer unresponsiveness to irradiated rats. However, host-derived CD8+ cells are important in reestablishing unresponsiveness. In this study, unfractionated lymphoid cells and W3/25+ (CD4+) cells from CsA-treated rats with long-surviving PVG allografts demonstrated normal alloreactivity to PVG alloantigen in the mixed lymphocyte culture and failed to suppress the proliferative response of naive W3/25+ cells to donor-specific alloantigen. MRC OX8+ (CD8+) cells did not proliferate. Sera from CsA-treated rats had no effect on the MLC reactivity of cells from CsA-treated rats, suggesting that blocking or antiidiotypic antibodies did not diminish alloreactivity. IL-2 production by W3/25+ cells from CsA-treated rats was similar to that by W3/25+ cells from naive rats. Specific cytotoxic T cells to PVG were generated in MLC, and the frequency of precursor cytotoxic lymphocytes in CsA-treated rats was similar to that in naive DA rats. In an in vitro assay testing response to idiotype, neither W3/25+ or MRC OX8+ cells from unresponsive rats proliferated. As CD4+ cells from CsA-treated rats lose their capacity to adoptively transfer specific unresponsiveness unless maintained in a cytokine-rich supernatant, all in vitro assays were performed with and without added cytokines, but no change in reactivity consistent with suppression was observed in any assay. CD4+ suppressor cells had no effect on conventional in vitro assays of alloreactivity, preventing the detection of the unresponsiveness in vitro.

Animals↗