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Biomedical subjects

E Ingulli

Publications and source records attributed to E Ingulli.

At least 19 recordsLinked to original sources
PubMed2006

CD154+ graft antigen-specific CD4+ T cells are sufficient for chronic rejection of minor antigen incompatible heart grafts.

We used a defined model system to address the role of minor histocompatibility antigen-specific CD4+ T cells in chronic rejection. The coronary arteries of vascularized heart grafts expressing the model antigen ovalbumin developed intimal hyperplasia in normal recipients and those lacking CD8+ T cells but not in those lacking CD4+ T cells. Furthermore, purified ovalbumin-specific CD4+ T cells from T-cell antigen receptor transgenic mice caused intimal hyperplasia in ovalbumin-expressing heart grafts in lymphocyte-deficient mice. The graft antigen-specific CD4+ T cells only caused intimal hyperplasia when expressing CD154 and were found in the intima of the affected coronary arteries along with CD40+ cells, CD11c+ dendritic cells and CD11b+, Gr-1+ monocytes. These results show that minor histocompatibility antigen-specific CD4+ T cells are required to cause the classical vascular changes of chronic rejection. They are capable of doing so without contributions from other lymphocytes, and may cause intimal hyperplasia by using CD154 to stimulate other non-lymphoid cells in the intima.

Animals↗
PubMed2001

Single-cell analysis of signal transduction in CD4 T cells stimulated by antigen in vivo.

Flow cytometry was used to study signaling events in individual CD4 T cells after antigen recognition in the body. Phosphorylation of c-jun and p38 mitogen-activated protein kinase was detected within minutes in all antigen-specific CD4 T cells in secondary lymphoid tissues after injection of peptide antigen into the bloodstream. The remarkable rapidity of this response correlated with the finding that most naive T cells are in constant contact with dendritic antigen-presenting cells. Contrary to predictions from in vitro experiments, antigen-induced c-jun and p38 mitogen-activated protein kinase phosphorylation did not depend on CD28 signals and was insensitive to inhibition by cyclosporin A. Our results highlight the efficiency of the in vivo immune response and underscore the need to verify which signaling pathways identified in vitro actually operate under physiological conditions.

Animals↗
PubMed2001

CD47 (integrin-associated protein) engagement of dendritic cell and macrophage counterreceptors is required to prevent the clearance of donor lymphohematopoietic cells.

Integrin-associated protein (CD47) is a broadly expressed protein that costimulates T cells, facilitates leukocyte migration, and inhibits macrophage scavenger function. To determine the role of CD47 in regulating alloresponses, CD47(+/+) or CD47(-/-) T cells were infused into irradiated or nonconditioned major histocompatibility complex disparate recipients. Graft-versus-host disease lethality was markedly reduced with CD47(-/-) T cells. Donor CD47(-/-) T cells failed to engraft in immunodeficient allogeneic recipients. CD47(-/-) marrow was unable to reconstitute heavily irradiated allogeneic or congenic immune-deficient CD47(+/+) recipients. These data suggested that CD47(-/-) T cells and marrow cells were cleared by the innate immune system. To address this hypothesis, dye-labeled CD47(-/-) and CD47(+/+) lymphocytes or marrow cells were infused in vivo and clearance was followed. Dye-labeled CD47(-/-) cells were engulfed by splenic dendritic cells and macrophages resulting in the clearance of virtually all CD47(-/-) lymphohematopoietic cells within 1 day after infusion. Host phagocyte-depleted CD47(+/+) recipients partially accepted allogeneic CD47(-/-) T cells. Thus, dendritic cells and macrophages clear lymphohematopoietic cells that have downregulated CD47 density. CD47 expression may be a critical indicator for determining whether lymphohematopoietic cells will survive or be cleared.

Animals↗
PubMed2001

Cutting edge: in vivo identification of TCR redistribution and polarized IL-2 production by naive CD4 T cells.

TCR aggregation at the point of contact with an APC is thought to play an important role in T cell signal transduction. However, this potentially important phenomenon has never been documented during an immune response in vivo. Here we used immunohistology to show that the TCR on naive Ag-specific CD4 T cells in the lymph nodes of mice injected with Ag redistributed to one side of the cell. In cases where the APC could be identified, the TCR was concentrated on the side of the T cell facing the APC. In those T cells that produced IL-2, the TCR and IL-2 localized to the same side of the cell. In vivo IL-2 production depended on costimulatory signaling through CD28, whereas TCR redistribution did not. These results show that Ag-stimulated CD4 T cells produce IL-2 in a polarized fashion and undergo CD28-independent TCR redistribution in vivo.

Animals↗
PubMed2001

In vivo activation of antigen-specific CD4 T cells.

Physical detection of antigen-specific CD4 T cells has revealed features of the in vivo immune response that were not appreciated from in vitro studies. In vivo, antigen is initially presented to naïve CD4 T cells exclusively by dendritic cells within the T cell areas of secondary lymphoid tissues. Anatomic constraints make it likely that these dendritic cells acquire the antigen at the site where it enters the body. Inflammation enhances in vivo T cell activation by stimulating dendritic cells to migrate to the T cell areas and display stable peptide-MHC complexes and costimulatory ligands. Once stimulated by a dendritic cell, antigen-specific CD4 T cells produce IL-2 but proliferate in an IL-2--independent fashion. Inflammatory signals induce chemokine receptors on activated T cells that direct their migration into the B cell areas to interact with antigen-specific B cells. Most of the activated T cells then die within the lymphoid tissues. However, in the presence of inflammation, a population of memory T cells survives. This population is composed of two functional classes. One recirculates through nonlymphoid tissues and is capable of immediate effector lymphokine production. The other recirculates through lymph nodes and quickly acquires the capacity to produce effector lymphokines if stimulated. Therefore, antigenic stimulation in the presence of inflammation produces an increased number of specific T cells capable of producing effector lymphokines throughout the body.

Animals↗
PubMed2000

TRANCE, a tumor necrosis factor family member, enhances the longevity and adjuvant properties of dendritic cells in vivo.

Mature dendritic cells (DCs) are powerful antigen presenting cells that have the unique capacity to migrate to the T cell zone of draining lymph nodes after subcutaneous injection. Here we report that treatment of antigen-pulsed mature DCs with tumor necrosis factor (TNF)-related activation-induced cytokine (TRANCE), a TNF family member, before immunization enhances their adjuvant capacity and elicits improved T cell priming in vivo, such that both primary and memory T cell immune responses are enhanced. By enumerating migratory DCs in the draining lymph nodes and by studying their function in stimulating naive T cells, we show that one of the underlying mechanisms for enhanced T cell responses is an increase in the number of ex vivo antigen-pulsed DCs that are found in the T cell areas of lymph nodes. These results suggest that the longevity and abundance of mature DCs at the site of T cell priming influence the strength of the DC-initiated T cell immunity in situ. Our findings have the potential to improve DC-based immunotherapy; i.e., the active immunization of humans with autologous DCs that have been pulsed with clinically significant antigens ex vivo.

Adjuvants, Immunologic↗
PubMed1998

Visualization of specific B and T lymphocyte interactions in the lymph node.

Early events in the humoral immune response were visualized in lymph nodes by simultaneous tracking of antigen-specific CD4 T and B cells after immunization. The T cells were initially activated in the T cell areas when the B cells were still randomly dispersed in the B cell-rich follicles. Both populations then migrated to the edges of the follicles and interacted there, resulting in CD154-dependent B cell proliferation and germinal center formation. These results provide visual documentation of cognate T-B cell interactions and localize them to the follicular border.

Adoptive Transfer↗
PubMed1998

Antigen-specific CD4+ T cells that survive after the induction of peripheral tolerance possess an intrinsic lymphokine production defect.

Injection of soluble foreign antigen without an adjuvant induces a state of antigen-specific immunological unresponsiveness. We investigated the cellular mechanisms that underlie this form of peripheral tolerance by physically tracking a small population of ovalbumin (OVA) peptide/I-Ad-specific, CD4+ T cell receptor (TCR) transgenic T cells following adoptive transfer into normal recipients. Injection of OVA peptide in the absence of adjuvant caused the antigen-specific T cells to proliferate for a brief period after which most of the T cells disappeared. The remaining OVA-specific T cells had converted to a memory phenotype but were poorly responsive in vivo as evidenced by a failure to accumulate in the draining lymph nodes following immunization with OVA peptide in adjuvant. These surviving T cells possessed a long-lasting, but reversible, defect in Il-2 and TNF-alpha production and in vivo proliferation, but did not gain capacity to produce Th2-type cytokines or suppress the clonal expansion of T cells specific for another antigen. Therefore, some antigen-specific T cells survive this peripheral tolerance protocol but are functionally unresponsive due to an intrinsic activation defect.

CD4-Positive T-Lymphocytes↗
PubMed1997

In vivo detection of dendritic cell antigen presentation to CD4(+) T cells.

Although lymphoid dendritic cells (DC) are thought to play an essential role in T cell activation, the initial physical interaction between antigen-bearing DC and antigen-specific T cells has never been directly observed in vivo under conditions where the specificity of the responding T cells for the relevant antigen could be unambiguously assessed. We used confocal microscopy to track the in vivo location of fluorescent dye-labeled DC and naive TCR transgenic CD4(+) T cells specific for an OVA peptide-I-Ad complex after adoptive transfer into syngeneic recipients. DC that were not exposed to the OVA peptide, homed to the paracortical regions of the lymph nodes but did not interact with the OVA peptide-specific T cells. In contrast, the OVA peptide-specific T cells formed large clusters around paracortical DC that were pulsed in vitro with the OVA peptide before injection. Interactions were also observed between paracortical DC of the recipient and OVA peptide-specific T cells after administration of intact OVA. Injection of OVA peptide-pulsed DC caused the specific T cells to produce IL-2 in vivo, proliferate, and differentiate into effector cells capable of causing a delayed-type hypersensitivity reaction. Surprisingly, by 48 h after injection, OVA peptide-pulsed, but not unpulsed DC disappeared from the lymph nodes of mice that contained the transferred TCR transgenic population. These results demonstrate that antigen-bearing DC directly interact with naive antigen-specific T cells within the T cell-rich regions of lymph nodes. This interaction results in T cell activation and disappearance of the DC.

Animals↗
PubMed1997

Use of adoptive transfer of T-cell-antigen-receptor-transgenic T cell for the study of T-cell activation in vivo.

Adoptive transfer of TCR-transgenic T cells uniformly expressing an identifiable TCR of known peptide/MHC specificity can be used to monitor the in vivo behavior of antigen-specific T cells. We have used this system to show that naive T cells are initially activated within the T-cell zones of secondary lymphoid tissue to proliferate in a B7-dependent manner. If adjuvants or inflammatory cytokines are present during this period, enhanced numbers of T cells accumulate, migrate into B-cell-rich follicles, and acquire the capacity to produce IFN-gamma and help B cells produce IgG2a. If inflammation is absent, most of the initially activated antigen-specific T cells disappear without entering the follicles, and the survivors are poor producers of IL-2 and IFN-gamma. Our results indicate that inflammatory mediators play a key role in regulating the anatomic location, clonal expansion, survival and lymphokine production potential of antigen-stimulated T cells in vivo.

Adjuvants, Immunologic↗
PubMed1996

Impact of age on renal graft survival in children after the first rejection episode.

Infants are thought to be more immunoreactive and at a greater risk for developing irreversible rejection compared with older children. We investigated this by analyzing patient and graft survival rates, incidence of acute rejection, reversibility of acute rejection, development of a subsequent acute rejection, and incidence of graft loss due to rejection in 154 children (< 18 years of age) after primary renal transplantation. Most patients (n = 139) were treated with quadruple immunosuppression (antibody, azathioprine, prednisone, cyclosporine). Treatment of the first acute rejection episode (ARE) consisted of antibody and increased prednisone (68%) or increased prednisone alone (30%), and was not significantly different between the age groups. Transplants were from living donors (LRD) in 80% of cases. Patients were followed for at least 1 year (mean 58 +/- 30 months); 68% (105/154) of recipients experienced 1 or more ARE. The incidence of ARE was significantly lower in patients < 2 years of age (45%) compared with patients 2-5 (76%, P = 0.01), 6-12 (78%, P = 0.005), and 13-17 (76%, P = 0.009) years of age. There was no significant difference in the 1-, 2- and 5-year patient or graft survival rates, the development of a subsequent acute rejection, or the incidence of graft loss due to acute rejection when analyzed by age group. These data suggest that the impact of an ARE is similar for younger and older children in our population receiving predominantly LRD transplants and quadruple immuno-suppression.

Acute Disease↗
PubMed1995

An analytical review of growth hormone studies in children after renal transplantation.

With steady improvement in 1- and 5-year patient and graft survivals in the last decade, rehabilitation of the child is the major focus of the transplant physician. The notion that the elimination of the uremic milieu should enable children to grow has not been born out over time, and growth retardation continues to be a serious morbidity in many children despite a well-functioning renal allograft. In children with chronic renal failure prior to renal transplantation, recombinant human growth hormone (rhGH) has been recently shown in controlled trials to improve growth. The use of rhGH in children after renal transplantation is controversial, since uncontrolled studies have questioned its safety. Acute rejection and graft loss have been reported in children after the initiation of rhGH. This study analyzes the data regarding the safety and efficacy of rhGH in children after renal transplantation as presented in seven current published reports. The demographic characteristics of the patients, the dose and duration of rhGH therapy, the "growth" rates of the patients before and after rhGH therapy, renal function before and after rhGH therapy, and other possible complications are reviewed. Based on this analysis, suggestions for future studies are made.

Child↗
PubMed1995

Focal segmental glomerulosclerosis in children.

Idiopathic focal segmental glomerulosclerosis is a histologic diagnosis that usually presents as the nephrotic syndrome but, unlike minimal change disease, often leads to renal failure in children. Standard therapies used to treat the proteinuria are often futile, and thus patients are at risk for the multiple complications resulting from persistent, severe proteinuria. Eventually, end-stage renal failure ensues, and the possibility of the disease recurring in the transplanted renal allograft is worrisome. This report reviews the clinical features and outcomes of idiopathic focal segmental glomerulosclerosis in children, the response to newer treatment options, and new insights into understanding what factors may be involved in causing the disorder.

Child↗
PubMed1995

Aggressive, long-term cyclosporine therapy for steroid-resistant focal segmental glomerulosclerosis.

Short-term cyclosporine (CsA) has been shown to reduce the proteinuria in refractory nephrotic syndrome, but the effect on disease progression has not been evaluated. This study was undertaken to evaluate whether maintenance CsA therapy in steroid-resistant focal segmental glomerulosclerosis (FSGS) will prevent progression to ESRD. Twenty-one black and Hispanic children (mean age, 8.4 +/- 4.5 yr) with biopsy-proven, steroid/cyclophosphamide-resistant FSGS were treated with CsA (initiated at 6 mg/kg per day and titrated to the serum cholesterol level to achieve a response). The mean CsA dose was 7 (4 to 20) mg/kg per day, the duration of CsA therapy was 27.5 (3 to 97) months, and the duration of follow-up was 8.5 +/- 4.7 yr. At the end of CsA therapy, the mean (+/- SE) proteinuria fell from 6.2 +/- 0.2 to 2.0 +/- 0.1 g/24 h (P < 0.001), the mean albumin rose from 1.95 +/- 0.04 to 3.41 +/- 0.04 g/dL (P < 0.001), the mean cholesterol decreased from 472 +/- 12.7 to 257 +/- 5.3 mg/dL (P < 0.005), and the mean creatinine rose from 0.79 +/- 0.02 to 1.16 +/- 0.03 mg/dL (P < 0.005). Seven children continue to receive maintenance CsA therapy, and 14 patients have had CsA stopped: 6 for an increase in serum creatinine and/or continued proteinuria, 5 for sustained remission, 2 for noncompliance, and 1 for pregnancy. Five (24%) of the 21 patients progressed to ESRD.(ABSTRACT TRUNCATED AT 250 WORDS)

Black People↗
PubMed1993

The beneficial effects of steroid withdrawal on blood pressure and lipid profile in children posttransplantation in the cyclosporine era.

Steroid therapy posttransplantation has been correlated with hyperlipidemia and hypertension. With improved graft survivals in the cyclosporine (CsA) era, post-tx hyperlipidemia and hypertension may place children at high risk for early atherosclerosis. Presently there are no large studies assessing the metabolic effects of steroid withdrawal in tx children. Thus, we report on the effect of prednisone withdrawal on blood pressure, weight, and serum lipid levels in children post-tx maintained on CsA alone. Pred taper is attempted in patients on CsA (6-7 mg/kg/day) with stable graft function and is extended over a 6-month period. Once a rejection is diagnosed pred is restarted and no future attempts to withdraw are made. BP, weight, and overnight fasting serum cholesterol (Schol) levels were measured 1 month prior to complete withdrawal (A), and after 6 months without pred (B). In patients requiring the restart of pred, subsequent measurements were obtained 6 months later (C). Of 74 tx children, 7 had primary nonfunction. Pred was successfully withdrawn in 49% (33) of the remaining 67. Of these patients, 42% (14/33) are still maintained off pred with stable renal function for a mean duration of 58.5 months (range 8-99 months). Nineteen patients had to be restarted on pred secondary to rejection between 7-36 months after withdrawal. Three of the patients subsequently lost their grafts to further rejection episodes. Univariate and multivariate analysis failed to identify clinical predictors of successful steroid withdrawal. The Schol at B, 171 +/- 5.4 mg/dl (mean +/- SEM) was lower (P < .001) than at A (249 +/- 10 mg/dl) or C (257 +/- 20 mg/dl). The systolic BP at B (108 +/- 2.8 mmHg) and diastolic BP at B (68 +/- 2.6 mmHg) were also lower (P < .001) than at A (122 +/- 3.2, 76 +/- 2.7 mmHg) or C (130 +/- 5, 80 +/- 3.2 mmHg), respectively. No difference in weight was noted. Lipid profile (total chol, triglyceride, HDL, VLDL, LDL) was measured in 10/14 patients off pred (mean age at sample 16.25 years) and was compared with 13 patients on pred (mean 15.5 years). Both the total chol (176 +/- 9.2, 265 +/- 8.3 mg/dl) and LDL (109 +/- 10, 167 +/- 9.2 mg/dl) were higher (P < .001) in the group on pred. Based on our findings of increased LDL and total chol, children on long-term pred therapy post-tx may be at increased risk for atherosclerotic disease.

Adolescent↗
PubMed1993

Synergism between the CD3 antigen- and CD2 antigen-derived signals. Exploration at the level of induction of DNA-binding proteins and characterization of the inhibitory activity of cyclosporine.

We have demonstrated earlier that the crosslinkage of the CD3/TCR complex with the CD2 antigen results in the proliferation of normal human T cells. The effect of this synergism was perceptible at the level of induction of the IL-2 gene, a process critical for T cell growth. To further understand the molecular and nuclear basis for this synergism, we have explored the induction of DNA-binding proteins in highly purified normal human T cells signaled via the CD3 and/or CD2 proteins. The effect of transmembrane signaling of T cells with ionomycin, and/or sn-1,2 dioctanoyl glycerol, was also determined. The emergence of nuclear binding proteins was investigated using interleukin-2 sequence specific oligonucleotide probes in the electrophoretic mobility shift assay. Our studies demonstrate for the first time that CD3 antigen-derived signals and CD2 antigen-derived signals are synergistic in inducing the emergence of transcription factors that bind to the NF-AT1, AP-1, and NF-kB sites located in the promoter/enhancer region of the IL-2 gene. Moreover, cyclosporine, at concentrations readily accomplished in clinical practice, was found to inhibit the emergence of these DNA-binding proteins in normal human T cells signaled via cell surface proteins implicated in antigen-dependent T cell activation and in T cells stimulated by mobilization of cellular calcium and activation of protein kinase C.

Antigens, Differentiation, T-Lymphocyte↗