Evidence for a shift from a type I lymphocyte pattern with HIV disease progression. Hemophilia Growth and Development Study

TH1 and TH2 cytokine mRNA and protein levels in human immunodeficiency virus (HIV)-seropositive and HIV-seronegative youths

The roles of cytokines in the progression of human immunodeficiency virus (HIV)-associated disease are controversial. The patterns of innate cytokine production have been postulated to shift from TH1- to TH2-type cytokines with the progression of HIV-associated disease. Although there have been studies of cytokines in children and adults, no data are available on cytokine production in healthy or HIV-infected adolescents. We analyzed and characterized cytokine mRNA and protein levels for gamma interferon, interleukin 2 (IL-2), IL-4, and tumor necrosis factor alpha and protein levels of IL-6 in both stimulated and unstimulated peripheral blood mononuclear cells obtained from a large longitudinal, observational cohort study of HIV-seropositive and -seronegative adolescents. We correlated cytokine results with viral load and CD4(+)-T-cell counts as critical markers of disease progression in HIV-infected adolescents. These data were used to examine hypotheses related to the TH1-to-TH2 cytokine shift in a sample of HIV-infected adolescents. Five hundred twenty subjects participating in the REACH (Reaching for Excellence in Adolescent Care and Health) Project of the Adolescent Medicine HIV/AIDS Research Network contributed blood samples. Samples selected for the cross-sectional data set analyzed had to meet selection criteria developed to minimize the potential confounding effects of acute intercurrent illnesses or infections, recent vaccination for hepatitis, and altered hormone status and to optimize congruence of cytokine measurements with assays of viral load and CD4(+)-T-cell counts. Group differences in the proportions of subjects with detectable levels of each cytokine marker were compared. In the subset of subjects with detectable cytokine values, differences in detected values were compared across subgroups defined by HIV serostatus and among HIV-seropositive subjects by three viral load classifications. The study sample was 65% HIV seropositive, 71% African-American, and 75% female with a mean age of 17.4 years. HIV-seropositive subjects were relatively healthy with mean and median CD4(+)-T-cell counts of 534 and 499 cells/mm(3), respectively. Only 8.1% of subjects had CD4(+)-T-cell counts below 200 cells/mm(3), and 25% had viral loads that were below the threshold of detection (<400 copies/ml). Detailed analyses of these data indicate that there were no differences in cytokines detected in HIV-seropositive and HIV-seronegative adolescents, and there was no apparent relationship between the cytokine measurements and the viral load or CD4(+)-T-cell categorization, the parameters selected as markers of HIV-associated disease status. These adolescents, including the HIV-seropositive subjects, were relatively healthy, and the HIV-infected subjects were at an early stage in the course of their HIV-associated disease. On the basis of our data, we conclude that, early in the course of HIV-associated disease in adolescents, there are no detectable shifts from TH1 to TH2 cytokine production.

Anergy and human immunodeficiency virus infection

Human immunodeficiency virus (HIV), the retrovirus associated with acquired immune deficiency syndrome (AIDS), induces a spectrum of immune abnormalities including a state of anergy in the host. This state is due to the binding of HIV envelope glycoprotein moieties to CD4 molecules and chemokine receptors. Resulting decrease in antigen presenting cell function and the interference with functioning of positive and negative regulatory molecules involved in signal transduction have an anergizing effect on the immune system. This effect is exemplified by diminished production of interleukin-2 (IL-2) and interferon-gamma and reduced expression of IL-2 receptor by CD4 helper cells of HIV patients. These immune abnormalities lead to clinically relevant immunological phenomena such as Type-1 to Type-2 switch, decrease in delayed-type hypersensitivity dermal reaction, etc. Insight into these interesting phenomena could pave the path for favorably altering the immunological milieu for drug and vaccine trials.

Anergy and acquired immune deficiency syndrome

Human immunodeficiency virus (HIV), the retrovirus associated with acquired immune deficiency syndrome (AIDS), acts as a super-antigen by binding to the variable region of the beta (V beta) chain of T-cell receptor (TCR). It's binding to CD4 molecules and chemokine receptors induces a spectrum of immune abnormalities including 'a state of anergy' in the host. This state is due to a defective function of T-helper cell-1 (Th-1), a reduction in production of lymphokines required for signal transduction, an impaired cytotoxic cell activation and a decrease in antigen presenting function of monocyte-macrophage cell lineage. These immune abnormalities form the basis for severe opportunistic infections and malignancies in the host. Malnutrition, micronutrient abnormalities, concomitant infections and genetic factors, etc., are some of the compounding co-factors that further contribute to 'the state of anergy'.

HIV-1-specific cellular immune responses among HIV-1-resistant sex workers

The goal of the present study was to determine whether there were HIV-1 specific cellular immune responses among a subgroup of women within a cohort of Nairobi prostitutes (n = 1800) who, despite their intense sexual exposure to HIV-1, are epidemiologically resistant to HIV-1 infection. Of the 80 women defined to be resistant, 24 were recruited for immunological evaluation. The HIV-1-specific T-helper responses were determined by IL-2 production following stimulation with HIV-1 envelope peptides and soluble gp120. Cytotoxic T lymphocyte responses were determined by lysis of autologous EBV-transformed B cell lines infected with control vaccinia virus or recombinant vaccinia viruses containing the HIV-1 structural genes env, gag and pol. Resistant women had significantly increased HIV-1 specific T-helper responses, as determined by in vitro IL-2 production to HIV-1 envelope peptides and soluble glycoprotein 120, compared with low-risk seronegative and HIV-1-infected controls (P < or = 0.01, Student's t-test). Seven of the 17 (41%) resistant women showed IL-2 stimulation indices > or = 2.0. HIV-1-specific CTL responses were detected among 15/22 (68.2%) resistant women compared with 0/12 low-risk controls (Chi-squared test, P < 0.001). In the two resistant individuals tested, the CTL activity was mediated by CD8+ effectors. Many HIV-1-resistant women show evidence of HIV-1-specific T-helper and cytotoxic responses. These data support the suggestion that HIV-1-specific T-cell responses contribute to protection against HIV-1 infection.

IL-10 in HIV infection: increasing serum IL-10 levels with disease progression--down-regulatory effect of potent anti-retroviral therapy

To examine the potential pathogenic role of IL-10 in HIV infection, we measured serum IL-10 levels in 51 HIV-infected patients and 23 healthy controls both on cross-sectional and longitudinal testing. All clinical groups (Centers for Disease Control (CDC) categories) of HIV-infected patients had significantly higher circulating IL-10 levels than controls, with the highest levels among the AIDS patients, particularly in patients with ongoing Mycobacterium avium complex (MAC) infection. Among 32 HIV-infected patients followed with longitudinal testing (median observation time 39 months), patients with disease progression had increasing IL-10 levels in serum, in contrast to non-progressing patients where levels were stable. While both IL-10 and tumour necrosis factor-alpha (TNF-alpha) increased in patients with disease progression, the IL-10/TNF-alpha ratio decreased in these patients, suggesting imbalance between these two cytokines. Finally, we found that highly active anti-retroviral therapy (HAART) induced a significant, gradual decrease in IL-10 levels but without normalization. These findings suggest a pathogenic role for IL-10 in HIV infection, and may suggest a possible role for immunomodulating therapy which down-regulates IL-10 activity in addition to concomitant potent anti-retroviral therapy in HIV-infected patients.

Immune determinants of organism and outcome in febrile hospitalized Thai patients with bloodstream infections

Opportunistic infections (OI) and the human immunodeficiency virus (HIV) cause significant morbidity and mortality in developing countries. Immune cell and cytokine profiles may be related to the type and course of OI and to the OI-HIV interaction. Examining cell-specific cytokine production ex vivo has only recently become feasible. In Thailand, 53 febrile, hospitalized adults were enrolled in a study of the immune correlates of bloodstream infections (BSI). On site, blood cells were stimulated ex vivo. Cell-surface antigens and eight intracellular cytokines were subsequently analyzed using flow cytometry to determine associations with mortality and the organism causing the BSI. By logistic regression analysis, the percentage of CD3(+) CD16/56(+) cells making tumor necrosis factor alpha (TNF-alpha) (P = 0.033) and the percentage of CD3(-) CD16/56(+) cells (NK) (P = 0.032) were related to HIV positivity. Lymph node enlargement with HIV infection and the percentage of CD3(+) CD16/56(+) making TNF-alpha were predictive of death. A lower percentage of CD3(+) CD8(+) lymphocytes making interleukin-8 (IL-8) (P = 0.005), fewer monocytes expressing CD14 (P = 0.009), and the percentage of CD3(+) CD8(+) cells producing gamma interferon (P = 0. 011) were associated with blood culture positivity and the causative organism. For every one point decrease in the percentage of CD3(+) CD8(+) cells making IL-8, the likelihood of a positive culture increased 23%; for every one point decrease in the percentage of monocytes expressing CD14, the likelihood of a positive culture increased by 5%. Only a few immune cell types and three of their related cytokines were significantly associated with HIV disease outcome or the BSI organism. These cell types did not include CD3(+) CD8(-) cells (a surrogate for CD4(+) cells), nor did they involve cytokines associated with a type I to type II cytokine shift, which might occur with advancing HIV infection. These associations support the premise that CD8(+) and CD16/56(+) lymphocytes play significant roles in HIV and type I infections.

The Dominant T-Helper Lymphocyte Function of HIV Infected Patients

In HIV infection, the decrease in the number and functional activity of lymphocytes is accompanied by atopia and an increased level of total IgE and some specific IgE antibodies. This could be explained by the Th2 dominance induced by HIV replication and so a Th1-Th2 switch could have prognostic value. We investigated the characteristic T-helper phenotype dominance and its relationship to cytokine expression and IgE immune response in the early stage of asymptomatic HIV infection. In the separated lymphocytes of i. asymptomatic HIV positive persons; ii. HIV negative homosexuals; iii. atopic patients; and iv. healthy controls, expression of mRNA for IFNg (Th1) and IL-10 (Th2) were determined by semiquantitative RT-PCR. The serum level of antibodies for HIV 1/2 and total/specific IgE were also determined. Transcription of mRNA of IFNg and IL-10 were more pronounced in HIV positive and atopic groups than in the healthy control, without lymphocyte phenotype dominance. In HIV negative persons, however, a significant Th2 dominance was detected. There was no significant difference in the IgE level between the 4 investigated groups. In the HIV positive cases, IL-10 expression and total serum IgE do not support a switch to Th2 dominance. In the atopic group, aside from the total IgE level, down regulation of IFNg was not observed. These results suggest a general activation of the immune system in the early stage of HIV infection.

Interleukin-10 gene expression induced by HIV-1 Tat and Rev in the cells of HIV-1 infected individuals

The role of cytokines in the regulation and function of the immune system is of great importance. In human immunodeficiency virus (HIV) infection, with progressive deterioration of cell-mediated immune response, cytokines are dysregulated. We have therefore investigated cytokine mRNA expression in type-1 and type-2 helper T cells of HIV-seropositive (HIV+) individuals, stimulated with mitogen (leukoagglutinin) and HIV-1 Tat and Rev peptides, previously found to induce proliferative T-cell responses in these individuals. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to detect interleukin 2 (IL-2), interferon gamma (IFN-gamma), IL-4, and IL-10 mRNAs. There was no difference in the mRNA expression of these cytokines when the cells of HIV-infected or noninfected individuals were polyclonally stimulated with the mitogen, as all cytokine mRNAs were detected in both groups. Baseline cytokine expression of unstimulated cells was, however, different in these two groups: the cells of HIV+ persons did not show comparable expression of mRNAs to HIV-seronegative (HIV+) individuals. When the cells of HIV+ individuals were stimulated with the peptides, 70% of the cases showed IL-10 mRNA expression, 20% IFN-gamma, and 10% IL-2, with no detection of IL-4 mRNA in any of the cases. Our results thus show that HIV-specific T-cell antigens induce production of IL-10 in HIV-infected individuals. The increase in IL-10 demonstrated here may have a role in hyperactivation of B cells, as well as in immunosuppression of T cells often seen in HIV-infected individuals.