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Query: UMLS:C0019693 (HIV)
 170,526 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

High levels of the soluble form of the CD8 molecule (sCD8) are detectable in the serum of HIV-1-infected patients. To investigate the mechanisms accountable for the release of this molecule we evaluated the presence of sCD8 in the supernatants obtained from in vitro cultures of highly purified CD8 cells isolated from 20 HIV-1-infected patients. At resting conditions cultured CD8 cells from HIV-1-infected patients released low amounts of sCD8; no statistically significant differences were observed between unstimulated cultures from HIV-1-seropositive patients and from HIV-1-seronegative subjects at risk for HIV-1 infection or normal healthy controls. Following in vitro activation of highly purified CD8 cells with a series of stimulatory agents, including phorbol myristate acetate, phytohemagglutinin (PHA) and recombinant interleukin-2, CD8 cells of HIV-1-infected patients significantly increased the shedding of sCD8. By expressing the results of activation-related release index (ARRI = sCD8 levels detected in the cultures with stimulatory agent/sCD8 levels detected in the unstimulated cultures), significantly higher values were observed upon PHA stimulation in HIV-1-infected patients than in control subjects. In order to identify the cell subset responsible for the enhanced release of sCD8 by PHA-stimulated cultures, we correlated the amounts of sCD8 detected in the supernatants with the phenotypic profile of CD8+ cells recovered from the cultures. A significant relationship was demonstrated between the percentage of CD8+/HLA-DR+ lymphocytes and sCD8 levels.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Shedding of the soluble form of the CD8 complex by CD8+/HLA-DR+ cells in HIV-1-infected patients. 183 45

The predominant antienvelope cell-mediated cytotoxicity in HIV-1-infected patients is a direct form of antibody-dependent cellular cytotoxicity (ADCC) in which circulating NK/K cells armed with cytophilic antibodies comprise a cytolytic effector cell complex capable of destroying HIV-1-expressing targets. This non-MHC-restricted form of virus-specific cytotoxicity is present in most infected patients, with maximum activity in early disease, gradually declining with disease progression. This endogenous cytotoxicity provides a focal point in the design of interventive strategies involving immune-based therapies. In the first such attempts, the lymphokine interleukin-2 has been employed in an effort to augment these potentially beneficial cytolytic reactivities. The focus of this article is to present the rationale, early clinical results, and future direction of such therapeutic approaches and, in doing so, to illustrate how careful basic research findings can be applied to the design of rational therapeutic strategies.
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PMID:Anti-HIV-1 ADCC: clinical and therapeutic implications. 184 18

Superinfection of latently human immunodeficiency virus (HIV)-infected rabbits with either Treponema pallidum or Shope fibroma virus (SFV) activates HIV expression. In addition, HIV-infected rabbits demonstrate prolonged cutaneous lesions (chancres) after intracutaneous challenge with T. pallidum, the causative agent of syphilis. Rabbits were infected by intravenous inoculation of 3 x 10(7) human T-cell lymphotrophic virus type III (HTLV-III)/B10 (HIV-1)-infected H9 (human) cells. Five weeks after initial infection, integrated HIV-1-specific DNA sequences were detected in the DNA of the peripheral blood lymphocytes of only one of eight rabbits using polymerase chain reactions (PCR); human DNA could not be detected at this time. Furthermore HIV infection could not be demonstrated by either seroconversion or PCR during the next 6 months. All HIV-infected rabbits remained clinically healthy and had normal white blood cell counts. Six months after HIV infection, four HIV-infected and two noninfected controls were superinfected with 10(6) T. pallidum in eight skin sites in the shaved skin of the back, and four infected and two control animals were challenged with an intradermal injection with SFV. After infection with either syphilis or SFV, the DNA from the white blood cells of all eight HIV-infected rabbits contained HIV sequences, and HIV sequences were demonstrated in dermal mononuclear cells of the syphilitic lesions by in situ hybridization. The SFV-induced tumors were rejected normally in the HIV-infected rabbits, but four of the four rabbits challenged with T. pallidum had delayed development of cutaneous lesions and three of four demonstrated larger and more prolonged lesions. White blood counts, mitogen responses, and interleukin-2 production remained within normal limits, and seroconversion for HIV was not detected. Three of four rabbits in a second group, challenged with T. pallidum 4 months after HIV-inoculation, also had delayed healing of syphilitic lesions. These results indicate that latent HIV-infection of rabbits may be activated by immunostimulation and that latently HIV-infected rabbits have impaired delayed hypersensitivity reactions. It is hypothesized that true latent HIV-infection in the rabbits is in monocytes and postulated that further immunostimulation may produce infection of lymphocytes and activation of disease.
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PMID:Syphilis superinfection activates expression of human immunodeficiency virus I in latently infected rabbits. 185 Sep 60

In vitro studies shows that recombinant tumour necrosis factor (TNF) alpha and beta, and interferon-gamma (IFN-gamma) can enhance HIV replication, and peripheral blood mononuclear cells (PBMC) infected with HIV in vitro secrete high levels of the same cytokines. As T cells secrete all three mediators, the capacity of T cell activation signals to trigger cytokine production in PBMC from HIV-infected individuals was investigated as such patients may be immunocompromised. We demonstrate that asymptomatic seropositives in CDC group II/III as well as patients who have progressed to CDC group IV of the disease proliferate efficiently to anti-CD3 antibody, recombinant interleukin-2 (rIL-2), phytohaemagglutinin (PHA), PHA plus phorbol 12,13 dibutyrate (PMA) but secrete significantly (P less than 0.05) higher amounts of TNF-alpha, TNF-beta and IFN-gamma compared with controls in response to the same stimulants. We also show a difference between group II/III and group IV patients with the latter secreting more TNF-alpha and IFN-gamma. The kinetics of TNF-alpha and -beta, and IFN-gamma production was stimulus dependent with overall levels varying in time for each stimulus. Furthermore, the kinetics of the response to all three stimulants were altered in seropositives; CDC group II/III and group IV patients secreted higher levels of cytokines over several time points compared to controls. The altered production of these mediators by HIV-infected patients may contribute to disease progression and to the pathogenesis of AIDS.
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PMID:Altered production of tumour necrosis factors alpha and beta and interferon gamma by HIV-infected individuals. 190 76

Adherent cells from human immunodeficiency virus (HIV)-infected subjects but not from normal blood donors, patients with Gram-positive or -negative bacteremia, active tuberculosis, toxoplasmosis, pulmonary aspergillosis, and cytomegalovirus infection produce spontaneously an activity which inhibits alpha chain of interleukin-2 (Tac) expression and interleukin 2 (IL-2) production by normal activated T cells and IL-2 production by these cells. A similar biologic activity was detected in culture supernatants of in vitro HIV-I-infected normal adherent and leukemic U937 cells. Tac-inhibitory activity is not cytotoxic and it could be detected in serum-free conditioned media. Recombinant granulocyte/macrophage colony-stimulating factor and phorbol myristate acetate stimulation of patients' and normal adherent cells did not enhance specifically the production of the Tac inhibitor. Biologically active conditioned media did not contain infectious virus as well as secreted p24, gp120 viral proteins; the biologic activity could not be abolished by anti-p24, anti-gp120, and anti-nef monoclonal antibodies or human purified polyclonal anti-HIV IgG. Gel filtration of conditioned media followed by anion exchange chromatography resulted in a 1,200-fold degree of purification and revealed that the biologically active molecule was cationic. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of this fraction and gel elution of the proteins showed that the biologic activity was associated with a 29-kD protein which was distinct from alpha- or gamma-interferon, tumor necrosis factor-alpha, and prostaglandin E2. The above findings demonstrate the production of inhibitory factor(s) during HIV infection, which might be involved in the pathogenesis of the patients' immune defect.
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PMID:Biological and biochemical characterization of a factor produced spontaneously by adherent cells of human immunodeficiency virus-infected patients inhibiting interleukin-2 receptor alpha chain (Tac) expression on normal T cells. 190 71

Infection by human immunodeficiency virus type 1 (HIV-1) is associated with cellular activation and expression of the interleukin-2 (IL-2) receptor. A genetically engineered fusion toxin, DAB486 IL-2, that contains the enzymatic site and translocation domain of diphtheria toxin and the receptor binding domain of IL-2 specifically kills cells that express high-affinity IL-2 receptors. This toxin selectively eliminated the HIV-1-infected cells from mixed cultures of infected and uninfected cells and inhibited production of viral proteins and infectious virus. Thus, cellular activation antigens present a target for early antiviral intervention.
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PMID:Selective elimination of HIV-1-infected cells with an interleukin-2 receptor-specific cytotoxin. 190 28

This overview summarizes current knowledge on the overall efficacy and potential contribution of antibody-dependent cellular cytotoxicity (ADCC) and lymphokine-activated killer cell (LAK) activities in evoking non-major histocompatibility complex (non-MHC) cytolytic responses to human immunodeficiency virus-1 (HIV-1)-infected targets. High titers of ADCC antibodies to the HIV-1 virion are present in HIV-1-seropositive populations at all stages of disease. These antibodies are broadly reactive with a large number of HIV-1 strains and are predominantly directed against envelope determinants spanning both gp120 and gp41. However, the relative ability of natural killer (NK) effectors, derived from HIV-seropositive individuals, to evoke ADCC responses becomes increasingly impaired with disease progression. HIV-1-seropositive individuals also show marked decreases in both production of and responsiveness to interleukin-2 (IL-2). HIV-1-seropositive individuals generally have the ability to generate ex vivo propagated LAK cells; however, these cytolytic effectors are less effective than their counterparts derived from healthy controls. Increased understanding and control of non-MHC-restricted cytotoxic-responses to HIV, and their induction by lymphokines, may lead to improved treatment strategies for the management of AIDS and related diseases.
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PMID:Role of antibody-dependent cellular cytotoxicity and lymphokine-activated killer cells in AIDS and related diseases. 194 Jun 15

To assess the value of feline immunodeficiency virus (FIV) infection as a model for human immunodeficiency virus (HIV) infection in man, we studied the impairment of certain immunological functions following natural or experimental FIV infection. Proliferative responses of peripheral blood mononuclear cells (PBMC) from symptomatic and asymptomatic cats after naturally or experimentally acquired FIV infection, induced by activation with the mitogens concanavalin A, pokeweed mitogen, or lipopolysaccharide or by stimulation with human interleukin-2 (IL-2), were significantly lower than the proliferative responses found with PBMC from noninfected control cats. Also IL-2 production levels of mitogen-activated PBMC from naturally infected symptomatic cats were significantly reduced. These data confirm that the pathogenesis of FIV infection in the cat, like HIV infection in man, is characterized by a serious malfunction of the immune system.
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PMID:Feline immunodeficiency virus (FIV) infection in the cat as a model for HIV infection in man: FIV-induced impairment of immune function. 196 59

We evaluated three cellular and five serologic markers that are affected by infection with the human immunodeficiency virus type 1 (HIV-1) for their ability to predict the progression to clinical acquired immunodeficiency syndrome (AIDS). The cellular markers were the number of CD4+ T cells, the number of CD8+ T cells, and the ratio of CD4+ T cells to CD8+ T cells. The serologic markers were the serum levels of neopterin (a product of stimulated macrophages), beta 2-microglobulin, soluble interleukin-2 receptors, IgA, and HIV p24 antigen. We evaluated the usefulness of these measures as markers of the progression to AIDS prospectively, over four years, in a cohort of 395 HIV-seropositive homosexual men who were initially free of AIDS. CD4+ T cells (expressed as an absolute number, a percentage of lymphocytes, or a ratio of CD4+ to CD8+ T cells) were the best single predictor of the progression to AIDS, but the serum neopterin and beta 2-microglobulin levels each had nearly as much predictive power. The neopterin level appeared to be a slightly better predictor than the beta 2-microglobulin level. The levels of IgA, interleukin-2 receptors, and p24 antigen had less predictive value. A stepwise multivariate analysis indicated that the best predictors, in descending order, were CD4+ T cells (the percentage of lymphocytes or the CD4+: CD8+ ratio), the serum level of neopterin or beta 2-microglobulin, the level of IgA, that of interleukin-2 receptors, and that of p24 antigen. The last three markers had little additional predictive power beyond that of the first two. We conclude that of the eight markers studied, progression to AIDS was predicted most accurately by the level of CD4+ T cells in combination with the serum level of either neopterin or beta 2-microglobulin. At least one of these two serum markers, which reflect immune activation, should be used along with measurement of CD4+ T cells in disease-classification schemes and in the evaluation of responses to therapy.
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PMID:The prognostic value of cellular and serologic markers in infection with human immunodeficiency virus type 1. 197 15

We investigated mechanisms by which the soluble native envelope glycoprotein gp120 of the human immunodeficiency virus (HIV-1) suppresses antigen-driven T cell responses. For this study, exogenous interleukin-2 (IL-2)-independent, antigen-specific, CD4 positive, human T-cell clones were developed by cyclic restimulation with soluble tetanus toxoid antigen. In the presence of soluble antigen and antigen-presenting cells (APC), T-cell clones proliferated and secreted IL-2. Purified gp120 suppressed the proliferative responses of the T-cell clones with concomitant suppression of IL-2 secretion; proliferative responses of CD8+ T cells preincubated with gp120 were not inhibited. A short pulse of 20 minutes with gp120 was sufficient to inhibit the proliferative response of the T-cell clones. Anti-CD3 monoclonal antibody (MoAb)-driven proliferation of the T-cell clones was also suppressed by gp120, but responses elicited by mitogens, phorbol myristate acetate (PMA) plus calcium ionophore, ionomycin, anti-CD2 MoAbs, and a combination of anti-CD3 plus anti-CD28 MoAb driven responses remained unaffected. Investigation of signal transduction events showed that antigen-driven early activation signals via translocation of protein kinase C (PKC), increase in intracellular inositol phosphates, and increase in intracellular calcium were suppressed in gp120 pretreated, tetanus toxoid antigen-stimulated T-cell clones. One mechanism of immune suppression by gp120 may involve interference with the initiation of signal transduction through the T-cell receptor complex.
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PMID:Inhibition of functional properties of tetanus antigen-specific T-cell clones by envelope glycoprotein GP120 of human immunodeficiency virus. 196 13


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