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Biomedical subjects

F Miedema

Publications and source records attributed to F Miedema.

At least 91 records · Page 5Linked to original sources
PubMed1996

T cell telomere length in HIV-1 infection: no evidence for increased CD4+ T cell turnover.

Progression to acquired immunodeficiency syndrome (AIDS) has been related to exhaustion of the regenerative capacity of the immune system resulting from high T cell turnover. Analysis of telomeric terminal restriction fragment (TRF) length, a marker for cellular replicative history, showed that CD8(+) T cell TRF length decreased but CD4(+) T cell TRF length was stable during the course of human immunodeficiency virus type-1 (HIV-1) infection, which was not explained by differential telomerase activity. This observation provides evidence that turnover in the course of HIV-1 infection can be increased considerably in CD8(+) T cells, but not in CD4(+) T cells. These results are compatible with CD4(+) T cell decline in HIV-1 infection caused by interference with cell renewal.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Single cell analysis of IL-4 and IFN-gamma production by T cells from HIV-infected individuals: decreased IFN-gamma in the presence of preserved IL-4 production.

The specific in vitro disturbance of capacities ascribed to Th1 cells in HIV-infected individuals suggests a switch from Th1 to Th2 lymphokine secretion. Indeed, when T cell clones are generated from HIV-infected individuals compared with controls, an increased percentage of Th0 clones is present upon HIV infection. We studied cytokine production in the supernatant of in vitro activated PBMC from a large group of HIV-infected patients at various stages of infection. IL-2, IFN-gamma, IL-4, IL-5, and IL-10 production all were decreased significantly, which does not support a switch to Th2 lymphokine secretion and is possibly due to the generalized impaired response of T cells from HIV-infected individuals to activation signals in vitro. Therefore, we investigated the capacity of single cells to produce a certain cytokine. Intracellular staining of IL-4- and IFN-gamma-producing cells revealed that T cells from HIV-infected individuals contained decreased numbers of IFN-gamma-producing cells, in the presence of normal percentages of cells with the capacity to produce IL-4. This resulted in significantly decreased IFN-gamma/IL-4 ratios in both CD4+ and CD8+ T cells. Thus, in agreement with previous findings in T cell clones, we conclude, from cytokine production upon stimulation of T cells in vitro, that there is a change in the cytokine balance to the Th2 side in HIV infection due to decreased Th1 and preserved Th2 cytokine production.

CD4-Positive T-Lymphocytes↗
PubMed1996

IL-12-induced IL-10 production by human T cells as a negative feedback for IL-12-induced immune responses.

IL-12 is an important initiator of cellular immune responses. This involves a positive feedback mechanism via IFN-gamma, which is abrogated when the pathogen that induces IL-12 production by the macrophage has been cleared. Here, we studied IL-10 as an additional negative regulator of IL-12-induced immune responses. Our results showed that upon stimulation with CD2 mAb, IL-12 was capable of inducing human T cells to produce IL-10. IL-12 was able to induce IL-10 production in primary T cells in the absence or the presence of accessory cells and in short-term cultures of established T cell clones. Moreover, T cell clones that had been cultured for longer periods in the presence of IL-12, when restimulated in the absence of IL-12, still produced high amounts of IL-10. Furthermore, we demonstrated that IL-10-mediated inhibition of T cell proliferation was dose dependent and depended on the time of addition of IL-10 and on the IL-12 concentration in culture. IL-10 has been identified as a dominant inhibitor of IL-12 production by APCs. The finding that IL-12 is capable of potently inducing its own inhibitor shows that the immune system is equipped with an intrinsic negative feedback mechanism that limits ongoing T cell activation. This indicates that the kinetics of T cell responses seem to be regulated by the ratio of IL-12 and IL-10 levels, which may gradually decline during the immune response.

Base Sequence↗
PubMed1996

Increased expression of CD80, CD86 and CD70 on T cells from HIV-infected individuals upon activation in vitro: regulation by CD4+ T cells.

T cells express CD28 and CD27 which transduce co-stimulatory signals after interaction with their ligands on antigen-presenting cells (APC). These ligands, CD80, CD86 and CD70, are also expressed to some extent on activated T cells. Here, we show that in human immunodeficiency virus (HIV)-infected individuals, CD28 and CD27 expression is decreased on CD8+ T cells. On the other hand, T cell stimulation in vitro induced high CD80, CD86 and CD70 expression on T cells from HIV-infected individuals. It appeared that an inverted CD4:CD8 T cell ratio could explain this enhanced expression of co-stimulatory ligands. Indeed, high expression levels of CD80, CD86 and CD70 were found on activated CD8+ T cells from HIV- individuals cultured in the absence of CD4+ T cells. Addition of CD4+ T cells prevented this up-regulation. However, in HIV-infected individuals, addition of excess autologous or healthy control CD4+ T cells did not completely counteract up-regulation of co-stimulatory ligand expression on CD8+ T cells. Thus, to some extent, CD8+ T cells in HIV-infected individuals appeared to be refractory to CD4+ T cell-mediated regulation of ligand expression in vitro. Activated T cells from HIV-infected individuals and activated CD8+ T cells from healthy controls were able to act as accessory cells in CD3-induced T cell proliferation, which was dependent on cell-cell contact. Thus, we showed that T cells from HIV-infected individuals express enhanced levels of co-stimulatory ligands upon activation, which provides them with accessory cell properties. Enhanced stimulatory potential of these nonprofessional APC may contribute to persistently high levels of immune activation in HIV infection related to disease progression.

Antigens, CD↗
PubMed1996

Low T cell reactivity to combined CD3 plus CD28 stimulation is predictive for progression to AIDS: correlation with decreased CD28 expression.

In 219 HIV-1-infected men of the Amsterdam cohort we measured CD4+ T cell numbers and in vitro T cell responses to CD3 MoAbs with or without CD28 costimulation and phytohaemagglutinin (PHA). The value of these markers was estimated for disease progression within 4 years. CD28 expression on T cells has been related to T cell responses. CD28 costimulation considerably enhanced T cell reactivity (approximately 8-10-fold) with lower coefficients of variation compared with reactivity to CD3 MoAb alone (median 5 versus 20). T cell reactivity to CD3 plus CD28 MoAb was decreased during HIV-1 infection and was besides CD4+ T cell numbers the only independent predictor for progression to AIDS. Compared with the group with high CD4+ T cell numbers the relative risk (RR) for the group with intermediate levels was 2.28, with low levels 5.20. In the groups with intermediate and low CD3 plus CD28 responses the RR was 2.04 and 4.16, respectively. The combined RR for both was 4.65 and 21.63. The independence of this marker was confirmed when the group with low CD4+ T cell numbers was subdivided into groups with high, intermediate and low T cell responses. The expansion of CD8+CD28- T cells was already apparent in HIV- homosexual men, but CD8+CD28+ T cells specifically decreased in patients with AIDS. CD28 expression on T cells correlated moderately with T cell responses to CD3 plus CD28 MoAb. T cell reactivity to CD3 MoAb in the presence of CD28 MoAb is a stronger prognostic marker than T cell reactivity to CD3 MoAb alone.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Lymphocyte subsets, apoptosis, and cytokines in patients with chronic fatigue syndrome.

Whether immunologic abnormalities correlate with fatigue severity and functional impairment in chronic fatigue syndrome (CFS) was investigated. Blood mononuclear cells were immunophenotyped and circulating ex vivo-produced cytokines were measured in 76 CFS patients and 69 healthy matched controls. Expression of CD11b on CD8 cells was significantly decreased in CFS patients. However, the previously reported increased expression of CD38 and HLA-DR was not confirmed. There was no obvious difference in apoptosis in leukocyte cultures, circulating cytokines, and ex vivo production of interleukin (IL)-1 alpha and IL-1 receptor antagonist. Endotoxin-stimulated ex vivo production of tumor necrosis factor-alpha and IL-beta was significantly lower in CFS. The immunologic test results did not correlate with fatigue severity or psychologic well-being was measured by Checklist Individual Strength, Beck Depression Inventory, and Sickness Impact Profile. Thus, these immunologic tests cannot be used as diagnostic tools in individual CFS patients.

ADP-ribosyl Cyclase↗
PubMed1996

Fine-specificity of cytotoxic T lymphocytes which recognize conserved epitopes of the Gag protein of human immunodeficiency virus type 1.

Human immunodeficiency virus type 1 (HIV-1) Gag-specific cytotoxic T lymphocyte (CTL) responses were studied in seven seropositive long-term asymptomatic individuals (CDC A1) with stable CD4 counts for more than 8 years. Using a set of partially overlapping peptides covering the whole Gag, five 15-20-mer peptides were found to contain CTL epitopes. Further characterization of these epitopes revealed a new HLA-A25-restricted CTL epitope in p24, p24(203-212) ETINEEAAEW. This region of Gag is highly conserved in clades B and D of HIV-1. Naturally occurring amino acid sequences, containing p24(203)D (consensus HIV-1 clades A, C, F, G and H) or p24(204)I (HIV-2ROD) were not recognized by CTL recognizing the index peptide. No virus variants with mutations in this sequence were found in peripheral blood mononuclear cells from the HIV-1-infected individual concerned during the 8 year observation period, indicating that the virus had not escaped from the observed CTL response.

Amino Acid Sequence↗
PubMed1995

Kinetics of Gag-specific cytotoxic T lymphocyte responses during the clinical course of HIV-1 infection: a longitudinal analysis of rapid progressors and long-term asymptomatics.

To gain more insight into the role of HIV-1-specific cytotoxic T lymphocytes (CTL) in the pathogenesis of AIDS, we investigated temporal relations between HIV-1 Gag-specific precursor CTL (CTLp), HIV-1 viral load, CD4+ T cell counts, and T cell function. Six HIV-1-infected subjects, who were asymptomatic for more than 8 yr with CD4+ counts > 500 cells/mm3, were compared with six subjects who progressed to AIDS within 5 yr after HIV-1 seroconversion. In the long-term asymptomatics, persistent HIV-1 Gag-specific CTL responses and very low numbers of HIV-1-infected CD4+ T cells coincided with normal and stable CD4+ counts and preserved CD3 mAb-induced T cell reactivity for more than 8 yr. In five out of six rapid progressors Gag-specific CTLp were also detected. However, early in infection the number of circulating HIV-1-infected CD4+ T cells increased despite strong and mounting Gag-specific CTL responses. During subsequent clinical progression to AIDS, loss of Gag-specific CTLp coincided with precipitating CD4+ counts and severe deterioration of T cell function. The possible relationships of HIV-1 Gag-specific CTLp to disease progression are discussed.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Evidence for intact costimulation via CD28 and CD27 molecules in hyporesponsive T cells from human immunodeficiency virus-infected individuals.

In the activation of T cells, the primary signal is antigen-specific and given through T cell receptor (TcR)/CD3 ligation. Furthermore, costimulatory molecules such as CD28 and CD27, provide an essential signal for activation through interaction with their ligands, present on the membrane of antigen-presenting cells. During asymptomatic human immunodeficiency virus (HIV)-1 infection, T cell function is progressively lost. Here, we investigated whether in the presence of impaired responses of T cells from HIV-infected individuals to signal one, costimulation through CD28 and CD27 after interaction with their natural ligands CD80 and CD70 is intact. T cell proliferative responses to signal one in combination with CD80 or CD70 were decreased in a large fraction of asymptomatically HIV-infected individuals. This was due to impaired responses of signal one but not to impaired responses to costimulation, since CD80 or CD70 did enhance signal one-mediated proliferative responses to a normal extent. Moreover, in individuals with proliferative responses to signal one that were decreased to 50% of normal T cell responses, costimulation even was increased compared to controls. Our results demonstrate that in HIV-infected individuals the response to costimulation is relatively preserved compared to responses to the first signal and point to the defect in T cells in HIV infection being primarily in the CD3/TcR-mediated pathway.

Antigens, CD↗
PubMed1995

Long-term survivors of HIV-1 infection.

The clinical course and outcome of HIV-1 infection are highly variable. A full spectrum of pathology has been observed, from rapid progression to AIDS within months of HIV-1 seroconversion, to asymptomatic survival for more than a decade. This phenomenon probably reflects the multiphasic and multifactorial nature of the virus-host interactions. Obviously, interest in the extremes now recognized in HIV-1 disease progression is growing, with the hope that mechanisms of protection may be found.

Disease Progression↗