B7 cosignal potentiates apoptosis of uninfected CD4+ T lymphocytic cell lines primed by HIV envelope proteins

In lymphoid organs, follicular dendritic cells (FDCs), monocytes, and macrophages are targets for HIV infection and reservoirs for infectious virus. Strikingly, the apoptotic cells in these sites are essentially uninfected CD4+ T lymphocytes, but lie in close proximity to infected cells or FDCs carrying trapped HIV virions. To decipher this apoptotic pathway, we have established a two-step experimental system that reproduces in vitro the HIV envelope protein-mediated apoptosis restricted to uninfected CD4+ T lymphocytic cell lines. In this assay, uninfected CD4+ T cell targets undergo apoptosis following an initial priming step on HeLa cells expressing functional HIV envelope proteins at their plasma membrane and a second and necessary stimulation step via the CD3-TCR complex. The CD4+ T lymphocytic cells susceptible to apoptosis are, in contrast, resistant to cell fusion mediated by HIV envelope protein and express SDF-1. FDCs and macrophages are known to be high B7 expressors. Thus in lymph nodes, the cells that have trapped HIV particles in immune complexes at the plasma membrane present both HIV envelope proteins and B7.1 at their surface. We mimicked this situation in vitro by priming CD4+ T lymphocytes on cells expressing the costimulatory molecule B7 in addition to HIV envelope proteins, and show that it resulted in an acceleration and a twofold increase in apoptosis. Finally, we characterized two enzymes, PI3Kinase and PI-PLC, which are both downstream effectors of the CD4 (HIV envelope protein receptor) and CD28 (B7 receptor) activation pathways, and that participated in the early steps of priming for apoptosis.     

Overexpression of Fas/CD95 and Fas-induced apoptosis in a patient with idiopathic CD4+ T lymphocytopenia.

The mechanisms of apoptosis have become better understood, in part with the discovery of Fas/CD95. We report the case of a patient characterized by a decreased CD4+ T cell count and an overexpression of Fas/CD95 resulting in apoptosis. A 54-year-old man presented with disseminated Mycobacterium xenopi infection. Analysis showed CD4+ T lymphopenia. Tests for human immunodeficiency virus (HIV) types 1 and 2 were negative. We compared the patient with eight healthy controls and five HIV-infected patients in terms of the expression of Fas/CD95 and Fas-mediated apoptosis of peripheral T lymphocytes. The percent of CD95+ cells in lymphocytes was 98% for the patient, and the mean percent of CD95+ cells in lymphocytes +/- SD for HIV-infected patients and healthy controls was 75% +/- 16% and 36% +/- 26%, respectively. The patient had a high level of spontaneous apoptosis, and apoptotic cells were all identified as being CD4+ T cells. Monoclonal antibodies to CD95 dramatically increased apoptosis of CD4+ T cells exclusively. CD4+ T lymphopenia observed in our patient correlated with an overexpression of Fas together with spontaneous and Fas-induced apoptosis.     

CD4+ blood lymphocytes are rapidly killed in vitro by contact with autologous human immunodeficiency virus-infected cells.

We have investigated the ability of human immunodeficiency virus (HIV)-infected cells to kill uninfected CD4+ lymphocytes. Infected peripheral blood mononuclear cells were cocultured with autologous 51Cr-labeled uninfected cells. Rapid death of the normal CD4-expressing target population was observed following a brief incubation. Death of blood CD4+ lymphocytes occurred before syncytium formation could be detected or productive viral infection established in the normal target cells. Cytolysis could not be induced by free virus, was dependent on gp120-CD4 binding, and occurred in resting, as well as activated, lymphocytes. CD8+ cells were not involved in this phenomenon, since HIV-infected CEMT4 cells (CD4+, CD8- cells) mediated the cytolysis of uninfected targets. Reciprocal isotope-labeling experiments demonstrated that infected CEMT4 cells did not die in parallel with their targets. The uninfected target cells manifested DNA fragmentation, followed by the release of the 51Cr label. Thus, in HIV patients, infected lymphocytes may cause the depletion of the much larger population of uninfected CD4+ cells without actually infecting them, by triggering an apoptotic death.     

Immunophenotypic Analysis of Peripheral Blood Mononuclear Cells Undergoing In Vitro Apoptosis After Isolation From Human Immunodeficiency Virus-Infected Children

Lymphocytes of human immunodeficiency virus (HIV)-infectedindividuals undergo accelerated apoptosis in vitro, but the subsets ofcells affected have not been clearly defined. This study examined therelationship between lymphocyte phenotype and apoptotic cell death inHIV-infected children by flow cytometry. Direct examination of thephenotype of apoptotic lymphocytes was accomplished using a combinationof surface antigen labeling performed simultaneously with the Tdtmediated Utp nick end-labeling (TUNEL) assay. In comparison to live cells, apoptotic lymphocytes displayed anoverrepresentation of CD45RO and HLA-DR expressing cells, while CD28and CD95 expressing cells were underrepresented. Lymphocytes expressingCD4, CD8, and CD38 were equally represented in apoptotic and livepopulations. When percent lymphocyte apoptosis follow- ingculture was examined independently with lymphocyte subsets in freshblood, apoptosis was negatively correlated with the percentage of CD4cells, but not with specific CD4 T-cell subsets. Although notcorrelated with the percentage of total CD8 cells, apoptosis waspositively correlated with specific CD8 T-cell subsets expressingCD45RO and CD95 and negatively correlated for CD8 T cells expressing CD45RA. These results provide direct evidence that a population ofactivated lymphocytes with the memory phenotype lacking the costimulatory molecule CD28 are especially prone to undergo apoptosis. The findings related to CD95 expression in fresh and apoptotic cellsimplicate Fas-dependent and Fas-independent pathways of apoptosis inHIV disease in children.     

Sequential analysis of apoptosis induction in peripheral blood mononuclear cells and lymph nodes in the early phase of pathogenic and nonpathogenic SIVmac infection.

To investigate the role of apoptosis in the early phase of HIV infection, we used macaques infected with simian immunodeficiency virus strain mac (SIVmac) as a primate model and examined sequentially the characteristics of apoptosis of lymphocytes in peripheral blood mononuclear cells (PBMCs) and lymph nodes in the early phase of SIVmac infection. Five macaques infected with a pathogenic strain of SIV, SIVmac239, were analyzed during the first 4 weeks after infection. Peripheral CD4+ and CD8+ cells transiently decreased at 1 week postinfection. The percentage of apoptotic cells in cultured PBMCs increased from about 2 weeks postinfection. The number of apoptotic cells in lymph node sections was higher on days 13 and 28 postinfection than before infection and on day 5 postinfection. Fas antigen expression on peripheral lymphocytes was upregulated from day 8 postinfection. These results indicate that apoptosis is induced about 2 weeks after SIVmac239 infection, following the upregulation of Fas antigen expression on lymphocytes. Since apoptosis was induced about 1 week after the decrease in peripheral CD4+ and CD8+ cell counts, it appears that the apoptosis induction does not play an important role in the transient lymphopenia in the early phase of SIVmac infection. In macaques infected with a nonpathogenic derivative of SIVmac239, SIVmac delta nef, apoptosis of lymphocytes was induced as it was in SIVmac239-infected macaques, but to a lesser degree, suggesting a correlation between the extent of apoptosis induction in lymphocytes in the early phase of SIVmac infection and the pathogenicity of SIVmac.     

Inferior clinical outcome of the CD4+ cell count-guided antiretroviral treatment interruption strategy in the SMART study: role of CD4+ Cell counts and HIV RNA levels during follow-up

BACKGROUND AND METHODS: The SMART study compared 2 strategies for using antiretroviral therapy-drug conservation (DC) and viral suppression (VS)-in 5,472 human immunodeficiency virus (HIV)-infected patients with CD4+ cell counts >350 cells/microL. Rates and predictors of opportunistic disease or death (OD/death) and the relative risk (RR) in DC versus VS groups according to the latest CD4+ cell count and HIV RNA level are reported. RESULTS: During a mean of 16 months of follow-up, DC patients spent more time with a latest CD4+ cell count <350 cells/microL (for DC vs. VS, 31% vs. 8%) and with a latest HIV RNA level >400 copies/mL (71% vs. 28%) and had a higher rate of OD/death (3.4 vs. 1.3/100 person-years) than VS patients. For periods of follow- up with a CD4+ cell count <350 cells/microL, rates of OD/death were increased but similar in the 2 groups (5.7 vs. 4.6/100 person-years), whereas the rates were higher in DC versus VS patients (2.3 vs. 1.0/100 person-years; RR, 2.3 [95% confidence interval, 1.5-3.4]) for periods with the latest CD4+ cell count >or= 350 cells/microL-an increase explained by the higher HIV RNA levels in the DC group. CONCLUSIONS: The higher risk of OD/death in DC patients was associated with (1) spending more follow-up time with relative immunodeficiency and (2) living longer with uncontrolled HIV replication even at higher CD4+ cell counts. Ongoing HIV replication at a given CD4+ cell count places patients at an excess risk of OD/death.     

A factor from CD8 cells of human immunodeficiency virus-infected patients suppresses HLA self-restricted T helper cell responses.

Defective in vitro T helper cell (Th) function can occur in asymptomatic human immunodeficiency virus (HIV)-seropositive (HIV+) individuals. A characteristic, early finding is the loss of an in vitro response to recall antigens, such as influenza A virus (FLU), despite an intact Th response to alloantigen (ALLO). To determine whether suppressor cells and/or inhibitory factors could contribute to this HIV-associated Th immunodeficiency, coculture studies were performed using peripheral blood leukocytes (PBLs) from monozygotic twins, one of whom was HIV-infected (HIV+) and one of whom was uninfected (HIV-seronegative, HIV-). In vitro Th function was measured as interleukin 2 production or proliferation to FLU and ALLO. Two pairs of twins were repetitively studied. A single HIV+ individual with multiple samples of cryopreserved PBLs over 6 years (including a HIV- specimen) was also studied. PBLs from the HIV+, but not from the HIV-, individuals demonstrated defective in vitro Th function in response to FLU but not to ALLO. PBLs from HIV+ individuals could induce a similar defect in the Th function of syngeneic or autologous HIV- PBLs. This suppression was generated by CD4-depleted, but not by CD8-depleted, PBLs. A suppressive factor from CD8+ cells of HIV+ donors was generated by 24-hr unstimulated cultures of HIV+ PBLs. This factor inhibited FLU but not ALLO responses of autologous, syngeneic, or allogeneic HIV- PBLs. This suppressive effect could not be explained by HIV infection or replication during the culture period. These results demonstrate that selective abrogation of Th function to recall antigens in HIV+ individuals is associated with an inhibitory factor produced by CD8+ T cells.     

The prevalence and pattern of skin diseases in relation to CD4 counts among HIV-infected police officers in Dar es Salaam

Among HIV-infected individuals, skin diseases cause significant morbidity and are frequently the initial indication of immunosuppression. From an on-going cohort study to determine prevalence and incidence of HIV infection among police officers (POs) and their suitability for HIV vaccine trials, a sub-study was carried out to determine the prevalence and pattern of skin diseases among HIV-infected POs and relate this to their immunodeficiency status. Consenting HIV-infected POs and their age and sex-matched HIV-negative officers were assessed for presence and type of skin diseases at their workplaces. A questionnaire was used for data collection. Immunodeficiency was measured by plasma CD4+ lymphocytes using flow cytometry. Between November 1998 and 31 December 2000, 716 POs were assessed. Overall HIV-1 prevalence was 17.7% (127/716). One hundred and ninety-one POs (26.7%) had at least one skin diagnosis. HIV-infected POs had significantly higher (41.7%) prevalence of skin diseases than HIV-uninfected POs (26.4%), P = 0.002. Fungal infections were common in both HIV-infected and uninfected POs. Among the HIV infected, other common diseases were: herpes zoster (11.8%); pruritic papular eruption (PPE) (7.1%); seborrheic dermatitis (5.5%); and Kaposi's sarcoma (KS) (1.6%). KS and PPE were associated with severe immunodeficiency, with mean absolute (percentage) CD4+ counts of 75.5 cells/microL (4.0%) and 71.7 cells/microL (4.8%), respectively. The values for herpes zoster and seborrheic dermatitis were 271.1 cells/micronL (12.4%) and 206.3 cells/microL (11.3%), respectively. Skin diseases were common among HIV-infected POs. PPE and KS are markers of severe immunodeficiency due to HIV. PPE, herpes zoster and KS strongly suggest underlying HIV-related immunodeficiency and patients with these conditions should be counselled and tested for HIV.     

Dysregulation of CD28 and CTLA-4 expression by CD4 T cells from previously immunodeficient HIV-infected patients with sustained virological responses to highly active antiretroviral therapy

OBJECTIVES: Current guidelines recommend commencing highly active antiretroviral therapy (HAART) in HIV-infected patients when CD4 T-cell counts reach 350 cells/microL. However, late-presenting HIV-infected patients with CD4 T-cell counts<50 cells/microL are still common. The ability of long-term HAART to normalize immune dysregulation in severely immunodeficient HIV-infected patients remains unclear. Here we address indices of immune dysregulation in previously severely immunocompromised HIV-infected patients treated with long-term HAART who had achieved increased CD4 T-cell counts and complete suppression of HIV viraemia. METHODS: We examined expression of CD28, cytotoxic T-lymphocyte antigen-4 (CTLA-4) and intracellular perforin by CD4 and CD8 lymphocytes from 25 highly selected HIV-infected patients [nadir CD4 T-cell counts <50 cells/microL, >4 years on HAART and >6 months of complete viral suppression (<50 HIV-1 RNA copies/mL)] and 18 HIV-seronegative age- and sex-matched controls. RESULTS: HIV-infected patients had lower percentages of CD28-expressing CD4 lymphocytes and higher percentages of CTLA-4-expressing CD4 lymphocytes than controls. The percentage of CTLA-4-expressing CD4 lymphocytes correlated inversely with that of CD28-expressing CD4 lymphocytes. The proportion of CD4 lymphocytes expressing perforin was generally low. However, more HIV-infected patients than controls had >1% of CD4 lymphocytes expressing perforin [11 of 25 (44%) vs. one of 18 (5.5%)]. The percentage of CD8 lymphocytes expressing perforin did not differ between HIV-infected patients and controls. Amongst HIV-infected patients, the percentage of perforin-expressing CD8 lymphocytes correlated inversely with nadir but not current CD4 T-cell count. CONCLUSIONS: Expression of CD28, CTLA-4 and perforin by CD4 lymphocytes remain dysregulated in HIV-infected patients with previous severe immunodeficiency, despite increased CD4 T-cell counts and control of HIV viraemia by HAART.     

Human immunodeficiency virus type 1 protease inhibitor modulates activation of peripheral blood CD4(+) T cells and decreases their susceptibility to apoptosis in vitro and in vivo.

CD4(+) T cells from patients with human immunodeficiency virus (HIV) infection undergo apoptosis at an increased rate, which leads to their depletion during disease progression. Both the Fas-Receptor (Fas-R) and interleukin-1beta (IL-1beta)-converting enzyme (ICE; caspase 1) appear to play a role in the mechanism of apoptosis of CD4(+) lymphocytes. Although Fas-R is upregulated on both CD4(+) and CD8(+) cells in HIV-infected patients, results from our laboratory and others indicate that, in patients with advanced disease, CD4(+) cells preferentially express ICE. Protease inhibitors have successfully halted the progression of HIV disease and increased CD4(+) T counts. In this study, we examined the effect of protease inhibitors on Fas-R (CD95), ICE (caspase 1) expression, apoptosis, and cell death in CD4(+) T cells of (1) HIV-infected patients who were receiving protease inhibitors, and (2) normal and patient CD4(+) T cells cultured with a protease inhibitor in vitro. Fifteen patients with advanced HIV disease on treatment showed dramatically decreased CD4(+) T-cell ICE expression, diminished apoptosis, and increased numbers of CD4(+) cells within 6 weeks of institution of protease inhibitor therapy, and before down-modulation of Fas-R (CD95) expression was evident. To determine the role of HIV infection, we studied the effect of ritonavir, a protease inhibitor, on normal and patient cells in vitro. Stimulated and unstimulated normal CD4(+) T cells, cultured with protease inhibitor, demonstrated markedly decreased apoptosis and ICE expression (P =. 01). While Fas-R expression was not significantly altered during short-term culture by such treatment, Fas-Ligand (Fas-L) membrane expression of phytohemagglutinin (PHA)-stimulated blood lymphocytes was decreased by protease inhibitor. In the presence of ritonavir, CD4(+) T cells from HIV-infected patients showed similar changes in ICE intracellular levels without alteration of Fas expression. In conclusion, protease inhibitors appear to decrease CD4(+) T-cell ICE expression and apoptosis before they affect Fas-R expression in HIV-infected patients. This action was independent of HIV infection, as similar effects were seen in CD4(+) T cells from normal controls. Some of the benefit of protease inhibitors may be related to modification of programmed cell death, which increases CD4(+) T-cell number. Whether this is due to directly to the changes effected in the caspase system remains to be determined.     

The in vitro effect of interferon-alpha 2a on CD95 expression of T cells in hepatitis B

BACKGROUND/AIMS: In chronic hepatitis B, apoptotic rate of peripheral cytotoxic T cells may be related with hepatocyte injury. We aimed to investigate Fas (CD95) expression of peripheral cytotoxic T cells and to show the in vitro effect of interferon-alpha 2a on Fas expression and apoptosis. METHODOLOGY: The study group consisted of 17 patients with chronic hepatitis B and control group consisted of 10 healthy subjects. Apoptotic cells were identified by flow-cytometric assay using Annexin V and propidium iodide. We used monoclonal antibodies stained by direct immunofluorescent method to show surface molecules. CH-11 monoclonal antibodies were used as anti-Fas antibodies. RESULTS: Basal expressions of CD95 and CD8+ CD95+ in the peripheral mononuclear cells were higher in chronic hepatitis B patients than controls. In vitro treatment with interferon-alpha 2a increased the percentage of CD8+ 95+ peripheral mononuclear blood cells in controls; this effect was less remarkable in patients with chronic B hepatitis, and the difference was not statistically significant. The number of apoptotic cytotoxic T cells also increased in 5 subjects of the study group and 3 subjects of controls; the percentage of CD95+ cells increased in 7 of 17 patients and 8 of 10 controls. The percentage of CD8+ 95+ cells and the apoptotic rate of CD8+ cells were not different between study group and controls after combined treatment with interferon-alpha 2a and monoclonal stimulating anti-Fas antibodies. CONCLUSIONS: We suggest that interferon-alpha 2a does not induce Fas-dependent apoptosis in CD8+ peripheral T cells of the patients with chronic hepatitis B, and CD95 molecules on peripheral cytotoxic T cells might be defective.     

Antiapoptotic effects of IL-15 on pulmonary Tc1 cells of patients with human immunodeficiency virus infection

In the early phases of human immunodeficiency virus (HIV) disease a T-cell alveolitis sustained by cytotoxic T lymphocytes (CTL) with anti-HIV activity occurs in the lung. With the progression of HIV disease, pulmonary CTL become infected and their cytotoxic activity declines. To investigate the potential causes leading to this phenomenon, we evaluated T cells obtained from the bronchoalveolar lavage (BAL) of 18 HIV-infected patients with T-cell alveolitis. BAL T cells were CD45R0+/CD8+ defined as Tc1 cells because they expressed cytoplasmic interferon gamma (IFN-gamma) and were CXCR3+/IL-12Rbeta2+. Furthermore, they bore the interleukin (IL)- 15 receptor, Fas antigen, and tumor necrosis factor receptor (TNFR) type II. When cultured for 24 h highly purified BAL T cells showed an excessive spontaneous apoptosis; after activation with anti-CD3 or ionomycin, the proportion of T cells undergoing cell death increased. Interestingly, we found a direct relationship between the predisposition to undergo spontaneous apoptosis and the levels of Fas expression by BAL T cells. Alveolar macrophages (AMs) expressed high levels of IL-15 which paralleled the intensity of T-cell infiltration in most patients. The predisposition of CD8 T cells to undergo cell death was downregulated by the incubation with IL-15; the protective effect of the cytokine was dose-dependent. Nonetheless, AMs also expressed proapoptotic molecules, including membrane TNF-alpha (mTNF-alpha). Based on these observations it may be suggested that an excessive, spontaneous, and activation-induced apoptosis of pulmonary lymphocytes may be observed in HIV lung and that AMs are major regulators of T-cell homeostasis.     

Ex vivo and in vitro effect of human immunodeficiency virus protease inhibitors on neutrophil apoptosis

Polymorphonuclear leukocytes (PMNL) from human immunodeficiency virus (HIV)-infected patients exhibit accelerated apoptosis and impaired functional activity. HIV protease inhibitor-based therapy produces improvements in both acquired and innate immune responses. Ex vivo and in vitro effects of HIV protease inhibitors on apoptosis and chemotaxis of PMNL were evaluated. After therapy, there was a rapid and significant decrease of PMNL apoptosis, which correlated with increased chemotactic function. These findings were found both in patients with immunological and virological response and in control subjects who showed an increase in CD4(+) T cell counts but no concomitant decline in HIV load. After in vitro treatment with ritonavir or indinavir, apoptosis of both HIV-infected and -uninfected PMNL markedly decreased and correlated with significant enhancement of chemotaxis. These results suggest that HIV protease inhibitors may improve the PMNL function by reducing the apoptosis rate and that this effect may, at least in part, be independent of their antiviral activity.     

Generation and characterization of ex vivo propagated autologous CD8+ cells used for adoptive immunotherapy of patients infected with human immunodeficiency virus

Cytolytic T lymphocytes play an important role in host defense against viral infections, including human immunodeficiency virus (HIV). In a phase I clinical trial (protocol 080 of the AIDS Clinical Trials Group), generation of CD8+ effector cells from peripheral blood of patients with acquired immunodeficiency syndrome (AIDS)-related complex (ARC) or AIDS and safety of autologous adoptive transfer of these cells were evaluated. For therapeutic infusions, CD8+ T cells were purified by positive selection on anti-CD8 monoclonal antibody-coated flasks from leukapheresed peripheral blood of seven patients. These CD8+ T cells were cultured in the presence of interleukin-2 and phytohemagglutinin for up to 3 weeks to obtain cells sufficient for therapeutic infusions (10(8) to 10(10)). All 31 cell cultures established from the seven patients and used for therapy were highly enriched in CD8+ (mean, 97%), CD8+HLA-DR+ (50%), cytotoxic CD8+CD11b- (82%), and memory CD29+ (78%) T lymphocytes. In vitro expanded CD8+ cells had excellent cytotoxic function at the time they were used for therapy, including HIV-specific activity against autologous targets infected with vaccinia vectors expressing HIV-IIIb antigens, gag, pol, and env. Anti-HIV activity of cultured CD8+ cells was significantly higher than that of autologous fresh peripheral blood lymphocytes. Our results show that CD8+ T lymphocytes obtained from peripheral blood of symptomatic HIV-infected patients can be purified, cultured to obtain large numbers of cells with enhanced anti-HIV activity, and safely infused into patients with AIDS as a form of immunotherapy.     

Interleukin 2 induces CD8+ T cell-mediated suppression of human immunodeficiency virus replication in CD4+ T cells and this effect overrides its ability to stimulate virus expression.

The nonlytic suppression of human immunodeficiency virus (HIV) production from infected CD4+ T cells by CD8+ lymphocytes from HIV-infected individuals is one of the most potent host-mediated antiviral activities observed in vitro. We demonstrate that the pleiotropic cytokine interleukin 2 (IL-2), but not IL-12, is a potent inducer of the CD8+ HIV suppressor phenomenon. IL-2 induces HIV expression in peripheral blood or lymph node mononuclear cells from HIV-infected individuals in the absence of CD8+ T cells. However, IL-2 induces CD8+ T cells to suppress HIV expression when added back to these cultures, and this effect dramatically supersedes the ability to IL-2 to induce HIV expression. Five to 25 times fewer CD8+ cells were required to obtain comparable levels of inhibition of viral production if they were activated in the presence of IL-2 as compared with IL-12 or no exogenous cytokine. Furthermore, IL-2 appeared either to induce a qualitative increase in HIV suppressor cell activity or to increase the relative frequency of suppressor cells in the activated (CD25+) CD8+ populations. Analyses of proviral levels in peripheral blood mononuclear cells suggest that CD8+ T cell-mediated lysis of in vivo infected cells is not induced by IL-2. These results have implications for our understanding of the effects of impaired IL-2 production during HIV disease as well as the overall effects of IL-2-based immunotherapy on HIV replication in vivo.     

Characterization of intestinal disease associated with human immunodeficiency virus infection and response to antiretroviral therapy

Combination antiretroviral therapies suppress human immunodeficiency virus (HIV) in peripheral blood, but the effect in gastrointestinal mucosa is uncertain. The occurrence of pathogen-negative diarrhea led to speculation that local HIV infection is etiologic. Mucosal cellular reservoirs for HIV were documented by use of several techniques. Correlations were found among gastrointestinal symptoms, histopathologic findings, cytokine expression, lymphoid apoptosis, and HIV RNA and protein expression in rectal mucosa. Disproportionate depletion of mucosal CD4+ lymphocytes also was found. The short-term effects of antiretroviral therapies were examined to test the hypothesis that these changes are directly related to mucosal HIV infection. Therapy was associated with decreased symptoms, with comparable drops in peripheral blood and mucosal HIV RNA contents, and by increases in blood and mucosal CD4+ lymphocyte contents. In addition, the number of apoptotic cells also declined during therapy. These results suggest that HIV plays a direct role in producing intestinal dysfunction.     

Isolation of HIV-1 from monocytes of individuals negative by conventional culture

To improve isolation of human immunodeficiency virus (HIV) from purified monocytic cell populations, a differential culture technique was applied to blood from HIV-seropositive individuals, culture-negative for HIV by routine culture. When 206 individuals were grouped by percentage of CD4+ lymphocytes, increases in viral isolation rates were significantly associated with declines in percentage of CD4+ cells (P less than .0001). Of 158 asymptomatic individuals, 78% had greater than 400 CD4+ lymphocytes/mm3. Only 19% were culture-positive using routine methods. Separation of peripheral blood mononuclear cells (PBMC) into purified lymphocyte and monocyte subpopulations for 12 asymptomatic patients and subsequent HIV culture of each purified subpopulation using three different indicator cell lines resulted in 100% virus recovery from purified monocytes cultured in the U-937 promonocytic cell line. Culture of purified lymphocytes in U-937 cells did not increase the isolation rate, whereas culture of patient PBMC in U-937 indicator cells and in allogeneic monocytes resulted in a 50% increase in HIV isolation. A monocytic indicator cell line added to routine culture methods may improve virus recovery from asymptomatic individuals.     

Human immunodeficiency virus infection and hepatitis C pathology

ABSTRACT: To investigate the possible influence of human immunodeficiency virus (HIV) infection on hepatitis C virus-related liver disease, liver morphology was evaluated in 160 HBsAg-negative patients with chronic hepatitis C, including 68 HIV-positive and 92 HIV-negative cases. No differences were detected in the severity of necro-inflammatory hepatic lesions between HIV-negative and HIV-positive patients when the CD4+ lymphocytes count exceeded 400 cells/mm³. In contrast, HIV-positive patients with CD4+ lymphocytes below 400/mm³ showed a significantly lower grade of portal inflammation and piecemeal necrosis. These results suggest that liver lesions in hepatitis C may largely depend on immunomediated mechanisms.     

In vivo and in vitro effects of statins on lymphocytes in patients with Hashimoto's thyroiditis

BACKGROUND: Statins have apoptotic effects on many cell types. Hashimoto's thyroiditis (HT) is an autoimmune disease in which cell-mediated autoimmune mechanisms are pathogenetically involved. OBJECTIVE: The aim of this study was to evaluate the in vivo effects of Simvastatin on thyroid function, lymphocyte subtypes and also to investigate the apoptotic effects of Simvastatin, Mevastatin, Pravastatin and Cerivastatin on lymphocytes from patients with HT. METHODS: In the first part of the study, 11 patients with HT and subclinical hypothyroidism (SH) were given Simvastatin (20 mg/day) for 8 weeks. Ten patients with SH and HT served as the control group. No treatment was given to controls. Thyroid function, C-reactive protein (CRP) levels and lymphocyte subtypes of both groups were determined before the study and after 8 weeks. In the second part of the study, the apoptotic effects of statins on lymphocytes were evaluated in patients with HT (n = 10) and normal subjects (n = 10) in vitro. Apoptosis was investigated by using Annexin-V and propidium iodide. Lymphocytes from patients and controls were incubated with different concentrations of Simvastatin, Cerivastatin, Mevastatin and Pravastatin. RESULTS: An increase in serum free tri-iodothyronine and free thyroxine levels and a decrease in TSH levels were observed (P < 0.05) with Simvastatin treatment. CD4+ cells and B lymphocytes increased whilst CD8+ cells, natural killer cells and activated T lymphocytes decreased significantly in the treatment group (P < 0.05). The CRP level of the group also decreased with Simvastatin but it did not reach significance (P = 0.057). None of parameters was found to be different from the baseline in the control group. In in vitro experiments, apoptosis was observed in CD3 + (both in CD8+ and CD4+ cells) with all statins in both patient and control samples. Mevalonate, which was used in experiments, reversed apoptosis in some but not all samples. CONCLUSIONS: The results of this study suggested that Simvastatin is an immune modulatory agent and improves thyroid function in patients with HT. This effect is probably mediated via lymphocyte apoptosis as demonstrated with in vitro experiments and is not confined to Simvastatin since Mevastatin, Pravastatin and Cerivastatin also induced apoptosis in lymphocytes.