Human immunodeficiency virus-induced cytotoxicity for CD8 cells from some normal donors and virus-specific induction of a suppressor factor

Quantitative alterations of the functionally distinct subsets of CD4 and CD8 T lymphocytes in asymptomatic HIV infection: changes in the expression of CD45RO, CD45RA, CD11b, CD38, HLA-DR, and CD25 antigens

We determined the representation in asymptomatic human immunodeficiency virus (HIV) infection of the CD45RO+ and CD45RO- CD45RA+ subsets of CD4+ and CD8+ T lymphocytes, CD11b+ and CD11b- subsets of CD8+ T cells, and activated populations of these subsets. Three-color flow cytometry was used to quantitate the different CD4+ and CD8+ T cell populations in 116 asymptomatic HIV+ individuals. In asymptomatic HIV+ infection there was a significant relative increase in the CD4+ CD45RO+ and CD8+ CD45RO+ T cell subsets, which express CD38 and DR antigens, that correlated strongly with the decline in total CD4+ T cells. In addition, we found a loss of CD4+ CD45RO- and CD8+ CD45RO- T cells associated with progression of HIV infection (as measured by the decline in total CD4+ T cells). Studies presented here also indicate that, with the progression of asymptomatic HIV infection, CD8+ CD11b- T lymphocytes showed a significant decrease, whereas CD8+ CD11b+ T cells were significantly increased. This study demonstrates that the progression of HIV infection in asymptomatic patients involves the increase in CD45RO+ subsets of CD4+ and CD8+ T cells, the increase in CD8+ CD11b+ T cells, the decrease in CD45RO- CD45RA+ subsets of CD4 and CD8 T cells, and the decline in CD8+ CD11b- T cells.

Alteration of intracellular potassium and sodium concentrations correlates with induction of cytopathic effects by human immunodeficiency virus

Increases in intracellular concentrations of potassium ([K+]i) and sodium ([Na+]i) occur concomitantly with cytopathic effects induced in a CD4+ T-lymphoblastoid cell line acutely infected by human immunodeficiency virus (HIV). This [K+]i increase was greater in cells infected by cytopathic HIV strains than in cells infected by less cytopathic strains. T cells persistently infected by HIV had an increased [K+]i but displayed an [Na+]i similar to that of mock-infected cells. HIV induced increases in [K+]i and [Na+]i after cytopathic infection of human peripheral blood mononuclear cells, but the magnitude of the Na+ changes did not correlate with the extent of the cytopathic effect. Enhanced movement of cations may osmotically drive water entry, resulting in balloon degeneration and lysis of HIV-infected cells. These observations offer potential approaches for antiviral therapies.

Lymphocyte transformation responses to phytohaemagglutinin and pokeweed mitogen in patients at differing stages of HIV infection: are they worth measuring?

AIMS

To determine whether the routine measurement of lymphocyte transformation responses to mitogenic stimuli provide any information additional to that available from routine T cell CD4 and CD8 analysis in patients with HIV infection.

METHODS

The case records of 197 immunologically investigated HIV seropositive patients were reviewed. The influence of disease stage on T lymphocyte subsets and lymphocyte transformation responses (LyTR) to phytohaemagglutinin (PHA) and Pokeweed mitogen was assessed.

RESULTS

The median CD3 and CD4 counts and LyTR to PHA and Pokeweed mitogen were highest in patients with persistent generalised lymphadenopathy (PGL) and decreased progressively in the order: asymptomatic patients, those with ARC, those with AIDS. LyTR to PHA was preserved in over 70% of all patients, but the response to Pokeweed mitogen was depressed in 8% of patients with PGL, 34% of asymptomatic patients, 68% of those with ARC and 78% of those with AIDS. Subnormal values of both CD4 + T cells and LyTR to Pokeweed mitogen were more common in patients with ARC and AIDS (68%) than in those who were asymptomatic or had PGL (20%).

CONCLUSIONS

CD4 T cell analysis and LyTR to Pokeweed mitogen, but not to PHA, both correlate with disease states in patients with HIV infection.

Human immunodeficiency virus proteins induce the inhibitory cAMP/protein kinase A pathway in normal lymphocytes

Proliferation of normal T lymphocytes is impaired by human immunodeficiency virus (HIV) proteins. In this paper, we demonstrate important parts of this mechanism. Initially, HIV-induced impairment of proliferation was shown to be an active process involving induction of protein tyrosine kinases in both CD4 and CD8 T cells. Furthermore, the impairment of cell proliferation was demonstrated to be linked to induction of the inhibitory protein kinase A (PKA) pathway by HIV proteins. This induction of PKA was accompanied by an increase in intracellular cAMP, which is necessary for the activation of PKA. Finally, increases in cAMP/PKA activity were shown to induce biochemical changes that impaired proliferation when cells were stimulated with phytohemagglutinin. This was demonstrated by showing that (i) agents, other than HIV proteins, that increase cAMP/PKA activity (cholera toxoid and 8-bromo-cAMP) also decreased T-lymphocyte proliferation; (ii) exposure of lymphocytes to HIV or cholera toxoid led to decreased membrane activity of the proliferation promoter protein kinase C upon stimulation; and (iii) agents that reduced cAMP generation neutralized the effect of HIV proteins and restored lymphocyte proliferation. These studies show that the HIV-induced augmentation of cAMP/PKA activity may be a key part of the mechanism responsible for all or part of the HIV-induced anergy of T lymphocytes.

Partial purification and identification of an immunosuppressive factor in AIDS sera

The cause of the profound immunodeficiency state induced by the human immunodeficiency virus (HIV) is not yet fully understood. Although direct cytopathic effects of the virus leading to the loss of CD4+ lymphocytes are believed to play a major role, soluble factors that cause lymphocyte dysfunction have also been identified. Here, we demonstrate that sera of AIDS patients contain a viral component capable of profoundly inhibiting normal T lymphocyte and natural killer cell functions. This factor (M(r) 30,000-50,000) is relatively resistant to proteolytic degradation, heat denaturation, extreme pH, and chemical modifications. It has been determined by Western blotting to share epitopes with the gp41 viral transmembrane component of HIV-1. This immunosuppressive factor has the characteristic property of inhibiting lymphocyte activation in the early stage (within 3 hr) of mitogenic stimulation. Concomitant with the inhibition of lymphocyte activation and interleukin 2 (IL-2) production, transcription of the IL-2 message is also reduced in a time-dependent manner. The unique time dependency of this immunosuppressive factor in lymphocyte activation could serve as a valuable tool to study the early steps of signal transduction in lymphocyte activation beyond membrane interaction.

Inhibition of lymphocyte proliferation induced in vitro by microbial antigens in HIV-infected subjects

In the course of a study of lymphocyte responses to microbial antigens in HIV-infected patients, we detected a previously unrecognized phenomenon of inhibition of lymphocyte baseline proliferation, induced by the presence of tetanus toxoid and Escherichia coli in the cultures. The effects of tetanus toxoid and Escherichia coli on lymphocyte proliferation in vitro were assessed by comparing the 3H-thymidine uptake by lymphocytes cultured without stimulant with the uptake of lymphocytes cultured in the presence of the antigens. Twenty-six patients with HIV infection (20 asymptomatic/persistent generalized lymphadenopathy, 2 AIDS-related complex, 4 AIDS) were investigated and the controls were 33 healthy individuals without evidence of HIV infection. Eight out of 22 asymptomatic/PGL and ARC patients progressed to full-blown AIDS in the mean follow-up of 26 months. The inhibition of proliferation was considered to be significant when the uptake of 3H-thymidine was reduced by 20% in the presence of the antigens. Using these criteria, 50% of the patients studied with tetanus toxoid and 36% of those studied with E. coli had evidence of the inhibitory phenomenon. Seven of the eight patients who developed AIDS during the observation period had the inhibitory phenomenon. In the group of patients without the inhibitory signs only one evolved to AIDS during the follow-up. The possibility of this phenomenon being related to an induction of suppressor cell activity by the antigens is discussed.

Dichotomy of two CD8+ lymphocyte subsets in HIV infection. Depletion of CD8+ CD3- and expansion of CD8+ CD3+ subsets: consequence on the CD4/CD8 ratio

In order to highlight the underlying mechanism(s) of the CD8 lymphocyte expansion in the HIV infection, two distinct CD8 subsets were analysed: T CD8bright+ CD3+ with MHC-restricted activity, and non-T CD8dim+ CD3-, which performs natural killer (NK) activity. It consists of a cross-sectional study including 168 HIV-infected patients (74 CDC stage II, 48 CDC stage III and 46 CDC stage IV) compared among them and to 60 healthy individuals. We observed an expansion of CD8+ CD3+ cells which masks a depletion of CD8+ CD3-. The comparative study showed that the expansion of the CD8+ CD3+ is relatively higher than that of total CD8+ lymphocytes and that the depletion of the CD8+ CD3- subset is severe, begins early and remains constant through the HIV progression. The comparison of CD4/CD8 and CD4/CD8+ CD3+ ratios showed that the latter could possibly be a better indicator in the HIV infection. The mechanism of inverted CD4/CD8 ratio in healthy individuals was also clarified. The CD8+ CD3+, CD8+ CD3- and CD4/CD8+ CD3+ parameters would be more specific markers than total CD8 and CD4/CD8 ratio especially in therapy trials.

AIDS virus infection and autoimmunity: a perspective of the clinical, immunological, and molecular origins of the autoallergic pathologies associated with HIV disease

The acquired immune deficiency syndrome (AIDS) is a viral-induced disorder of humans that is reaching pandemic proportions. The etiologic agent responsible for AIDS is recognized as a retrovirus termed the human immunodeficiency virus (HIV). This virus is both cytotropic and cytopathic for T lymphocytes in vitro, and patients with AIDS and HIV-related conditions invariably have serious T cell abnormalities, notably a reduced number of the helper/inducer (CD4+) subpopulation. There is now a substantial body of evidence to suggest that the AIDS virus triggers a diverse range of autoimmune phenomena. The purpose of this article is to summarize the clinical and immunopathological manifestations of autoimmunity in HIV infection and to provide a perspective of the possible origins and roles autoimmune reactions play in HIV disease progression.

Differential staphylococcal protein A-induced enhancement of natural killer cell activity of lymphocytes from HIV-seropositive individuals

A decrease in Natural Killer (NK) cell activity is a common feature of the immune dysfunction found in patients with HIV-induced acquired immune deficiency syndrome (AIDS). We and others have shown earlier that staphylococcal protein A (SpA) preparations enhance NK cell activity against tumor targets. The present study was aimed at exploring whether the decreased NK activity of lymphocytes from HIV seropositive subjects could be modulated or restored in vitro by SpA. Two types of HIV-seropositive subjects were studied: hemophiliac and non-hemophiliac; matched controls were chosen among hospital staff and HIV-seronegative hemophiliac volunteers. In vitro proliferation and interleukin-2(IL-2)/interferon gamma (IFN gamma) release in response to mitogens were also studied. NK cell responses of peripheral blood lymphocytes (PBL) of HIV-seropositives were lower than those of seronegatives. However, exposure of PBL from HIV-seropositive individuals to SpA boosted their NK cell responses against NK-resistant target cells of tumor origin. The decrease in NK activity could not be attributed to the low number of NK cells, since no significant difference in NK cell number was observed between HIV-seropositive individuals and controls. Mitogen-induced blastogenic responses were present in all four groups, as was the mitogen-induced IFN gamma release. We conclude that impaired NK activity and its boosting against NK-resistant targets after SpA induction is an important characteristic of lymphocytes of HIV-seropositive individuals regardless of the disease state and that this NK defect may not be irreversible.(ABSTRACT TRUNCATED AT 250 WORDS)

Human nonspecific suppressive lymphokines

Since the term "lymphokine" first appeared in print over 20 years ago, a tremendous number of these soluble mediators of the immune system have been described. Within the past few years, many human nonspecific suppressive lymphokines have been identified. This review discusses the historical basis of immunologic suppression and suppressor factors. Later reports describing suppressive human lymphokines are then grouped into four categories: primarily stimulatory lymphokines that also mediate certain suppressive activities, suppressive lymphokines produced during altered states of immunity, suppressive lymphokines produced by exogenously stimulated lymphocytes, and suppressive lymphokines produced by unstimulated lymphocytes. Recent work I have been involved in focusing on the human suppressive lymphokine soluble suppressor factor (SSF) is also discussed.

A soluble inhibitor of T lymphocyte function induced by HIV-1 infection of CD4+ T cells: characterization of a cellular protein and its relationship to p15E

Soluble suppressor factor (SSF), first described in association with HIV-1 infection in vivo, is a molecule(s) capable of inhibiting T cell-dependent immune reactivity. Its relationship to human immunodeficiency virus (HIV) was further defined as supernatants of mononuclear cell cultures from HIV-1-seropositive carriers, CD4+ T lymphocytes infected with HIV-1 in vitro, and a T cell hybridoma incorporating CD4+ lymphocytes from an HIV-1-seropositive individual were shown to elaborate factors with similar activity profiles. These factors were recognized antigenically by certain antibodies directed against epitopes of p15E, a transmembrane protein of murine leukemia virus which shares regions of identity with proteins deduced from human endogenous retroviral envelope transcripts as well as HIV. These reagents precipitated a single-chain, nonglycosylated, nonviral protein of molecular weight 57,000 Da from SSF-producing cells. There was no cross-reactivity with antisera recognizing the IL-2R alpha-chain (CD25) or tumor necrosis factor. This molecule was present in very low levels in PHA-activated T lymphocytes and was upregulated following their infection with HIV-1. Isolation of HIV-linked SSF should permit comparisons with other virion, cellular, and serum inhibitory substances described in AIDS, and perhaps suggest therapeutic strategies.