Correlation of in vitro immune defects with impaired gamma interferon response in human-immunodeficiency-virus-infected individuals

HIV-Specific CD8(+) T Lymphocytes in Blood of Long-Term HIV-Infected Hemophilia Patients

Hemophilia patients infected with human immunodeficiency virus (HIV) 30 years ago show increased proportions of activated CD8⁺DR⁺ blood lymphocytes. We hypothesized that this might indicate a cellular immune response directed against HIV and might be the reason for long-term clinical stability of these patients. CD8⁺ peripheral blood lymphocytes (PBL) reactive with six HIV and two cytomegalovirus (CMV) pentamers were determined in heparinized whole blood. Additional lymphocyte subsets as well as plasma cytokines and HIV-1 load were studied. Long-term HIV-infected hemophilia patients with (n=15) or without (n=33) currently detectable HIV-1 load in the plasma showed higher proportions of CD8⁺ lymphocytes reactive with HIV (p<0.001) and CMV pentamers (p=0.010) than healthy individuals. The cellular anti-HIV response tended to be stronger and more polyclonal in patients during periods of viral replication than in patients with retroviral quiescence (p=0.077). Anti-HIV CD8⁺ lymphocyte responses were strongest in patients with high counts of activated CD8⁺DR⁺ T (r=0.353; p=0.014) and low CD19⁺ B lymphocyte counts (r=−0.472; p=0.001). Patients with or without HIV-1 viral load showed normal Th1 and Th2 plasma cytokine levels and high plasma interleukin-6 (versus healthy controls, p=0.001) and tumor necrosis factor-α (p=0.020). Hemophilia patients who have been living with HIV for more than 30 years showed a polyclonal CD8⁺ T-cell response against HIV and CMV. This cellular antiviral immune response was strongest during periods of HIV-1 replication and remained detectable during periods of HIV-1 quiescence. We hypothesize that the consistent cellular anti-HIV-1 response in combination with highly active antiretroviral therapy ensures stability and survival of these chronically HIV-1–infected hemophilia patients.

Abnormalities in host defense associated with HIV infection

The broad variety of pulmonary infections encountered in human immunodeficiency virus (HIV)-infected individuals demonstrates that the host defense network is impaired. An improved understanding of these events in the lung can lead to specific interventions aimed at restoration of deficient function. This review summarizes the pulmonary host defense deficits in HIV-infected individuals, focusing on lymphocytes, alveolar macrophages, and neutrophils.

Increased peripheral blood leukocyte subsets with regulatory phenotype in clinically stable long-term HIV-infected hemophilia patients on HAART may be beneficial and contribute to a decrease in autoimmunity

After initiation of highly-active antiretroviral therapy (HAART), long-term HIV-infected hemophilia patients have been shown to lose autoantibodies against CD4(+) peripheral blood leukocytes (PBL), suggesting that HAART induces autoimmunity-blocking mechanisms. We compared cytokine levels and subpopulations of lymphocytes and dendritic cells (DC) in the blood of 40 long-term HIV(+) patients with those of 13 long-term HIV(-) hemophilia patients; 23 HIV(+) patients had a detectable retroviral load. Cell subsets were determined using flow cytometry and cytokine levels were measured using ELISA. HIV(+) patients showed higher proportions of DC subpopulations with immunostimulatory phenotypes (p < 0.01), CD8(+) PBL (p < 0.001), and IL-2 (p < 0.001) and sIL-2R plasma levels (p = 0.002) than HIV(-) patients. They also exhibited increased proportions of T PBL with immunosuppressive phenotypes such as CD3(+)CD4(+)CD25(+)Foxp3(+) (p = 0.001), and CD3(+)CD8(+)CD28(-)Foxp3(+) PBL (p < 0.001), and a decreased IL-7R expression on CD3(+)CD8(+) PBL (p = 0.001) compared to HIV(-) patients. Frequencies of CD3(+)CD4(+)CD25(+) PBL producing IL-2, IL-4, IL-10, IL-12, and/or IFN-gamma, and of CD3(+)CD4(+)CD28(-) PBL secreting IL-2 and/or IL-4 were lower in HIV(+) than in HIV(-) patients (p <or= 0.02). Proportions of CD4(+) PBL coated with IgG, IgM, and C3d were similar in HIV(+) and HIV(-) patients (p = n.s.). However, the proportion of CD4(+)gp120(+) PBL was higher in HIV(+) patients (p = 0.002), and associated with low CD3(+)CD4(+)CD25(+)Foxp3(+) PBL (p = 0.012). We conclude that long-term HIV-infected hemophilia patients on HAART show an adaptive immune response, presumably against HIV, in the presence of upregulated immunosuppressive T PBL, downregulated cytokine-producing CD4(+) PBL, and downregulated IL-7R expression on CD8(+) PBL. Increased immunoregulatory T PBL might decrease autoimmunity, thereby contributing to immunological reconstitution and stabilization of long-term HIV-infected hemophilia patients on HAART.

Interferon-gamma-mediated pathways and in vitro PBMC proliferation in HIV-infected patients

HIV infection is characterized by progressive immunodeficiency: HIV-infected peripheral blood mononuclear cells (PBMCs) cannot properly react to stimulation with allo-antigens and mitogens. In this study, we examined interferon-gamma (IFN-gamma)-mediated pathways and the proliferative response of mitogen-stimulated HIV-infected PBMCs in vitro. PBMCs of 30 HIV-infected patients were stimulated with the mitogens concanavalin A (Con A), phytohemagglutinin (PHA), and pokeweed mitogen (PWM). Mitogen stimulation induced expression of IFN-gamma, GTP cyclohydrolase I (GCH-I), and indoleamine (2,3)-dioxygenase (IDO) resulting in enhanced neopterin formation and tryptophan degradation by HIV-infected and control PBMCs. IFN-gamma concentrations correlated with neopterin levels and tryptophan degradation. Proliferative responses to PHA and PWM cytokine were lower in HIV patients, with IFN-gamma formation predicting proliferative responses. Higher mRNA expression of IFN-gamma, GCH-I and IDO after 6 h was related to better proliferative responses in HIV-infected PBMCs. In conclusion, induction of IFN-gamma and subsequent enzymes appears to importantly influence the proliferative response of HIV-infected PBMCs in vitro, suggesting a prominent role of the cytokine in the development of immunodeficiency.

Association of IL-12+ DC with High CD3+CD4-DR+ Lymphocyte Counts in Long-term HIV-infected Hemophilia Patients With Clinically Stable Disease

We investigated dendritic cell (DC) subsets as well as cellular and humoral immune parameters in long-term HIV-infected hemophilia patients with clinically stable disease. DC subsets were determined by their function to produce either IL-10 or IL-12. CD11c(+)CD83(+)CD40(+)IL-10(+) and CD11c(+)CD83(+)CD40(+)IL-12(+) DC were studied in freshly obtained blood samples of 28 HIV(+) and 15 HIV(-) patients and 39 healthy controls using four-color flow cytometry, and were analyzed in relation to blood lymphocyte subpopulation counts, proportions of IgG-coated CD4(+) blood lymphocytes, neopterin, and HIV-1 viral load in the plasma, and in vitro responses of patient lymphocytes to mitogens. Proportions and ratios of IL-10(+) DC and IL-12(+) DC were similar in HIV(+) and HIV(-) patients and healthy controls. Whereas IL-12(+) DC in HIV(+) patients were associated with high CD3(+)CD4(-)DR(+) lymphocyte counts, IL-10(+) DC were associated with the proportion of IgG-coated CD4(+) blood lymphocytes. These data suggest that long-term HIV-infected hemophilia patients with clinically stable disease have normal levels of functional IL-10(+) DC and IL-12(+) DC that might be involved in halting the progression of disease.

Natural killer (NK) cell stimulatory factor increases the cytotoxic activity of NK cells from both healthy donors and human immunodeficiency virus-infected patients

Natural killer cell stimulatory factor (NKSF), or interleukin 12 (IL- 12), is a heterodimeric lymphokine produced by B cells that has multiple effects on T and NK cell functions. NKSF at concentrations as low as 0.4 pM enhances the spontaneous cytotoxic activity of peripheral blood lymphocytes (PBL) against a variety of tumor-derived target cell lines and virus-infected target cells. The combined treatment of PBL with NKSF and IL-2 results in a less than additive enhancement of cytotoxicity. NKSF enhances the cytotoxic activity of spontaneously cytotoxic CD16+CD5- NK cells and does not confer cytotoxic activity to CD16-CD5+ T cells. PBL from patients infected with human immunodeficiency virus (HIV) have significantly lower cytotoxic activity against tumor-derived target cells and virus-infected target cells than PBL from control healthy donors. Treatment of PBL from HIV- infected patients with NKSF and/or IL-2 results in an increase of NK cell cytotoxicity against both types of target cells to levels similar to or higher than those of untreated PBL from healthy donors. PBL from HIV-infected patients produce interferon gamma in response to NKSF and/or IL-2, although at levels 5- or 10-fold lower than those produced by PBL from healthy donors. The multiple biological effects of NKSF, its activity at very low molar concentrations, and its ability to synergize with other physiological stimuli suggest that NKSF/IL-12 is a lymphokine likely to have physiological importance and considerable therapeutic potential.

Soluble IL-2 receptor and tumour necrosis factor-alpha in plasma of haemophilia patients infected with HIV

We measured plasma concentrations of soluble receptors for IL-2 (sIL-2R) and tumour necrosis factor-alpha (TNF-alpha) in 149 haemophilia patients. Soluble IL-2R levels were elevated in 37% of 62 HIV-seronegative patients (mean 570 +/- 27 U/ml versus 361 +/- 17 U/ml in the control group, P less than 0.0001), in 78% of 68 HIV-seropositive patients (928 +/- 49 U/ml, P less than 0.0001), and in 95% of 19 AIDS/ARC patients (1578 +/- 199 U/ml, P less than 0.0001 compared with controls and with HIV-seronegative patients; P less than 0.005 compared with HIV-seropositive asymptomatic patients). A negative correlation was observed between sIL-2R, relative and absolute numbers of CD4+ cells (P less than 0.0001), and CD4/CD8 ratios (P less than 0.0001). There was also a negative correlation between sIL-2R in plasma and the cellular expression of IL-2R (P less than 0.001). We found a significant association of sIL-2R and plasma neopterin (P less than 0.0001). With progression of the disease from HIV-seronegative to seropositive without symptoms and to full manifestation of AIDS/ARC, sIL-2R plasma levels increased. The highest levels were found at the time of diagnosis of AIDS/ARC, but the levels decreased again during the following 18 months. Eight per cent of HIV-seronegative patients, 32% of HIV-seropositive patients, and 24% of patients with AIDS/ARC had increased plasma TNF-alpha. We conclude that sIL-2R and TNF-alpha plasma levels are elevated in HIV-infected haemophilia patients and that sIL-2R is a marker for disease progression from asymptomatic HIV-seropositive to AIDS/ARC.

Reduction in intensity of Pneumocystis carinii pneumonia in mice by aerosol administration of gamma interferon

Pneumocystis carinii pneumonia in patients with AIDS may result from impaired local release of gamma interferon from lung lymphocytes and subsequent failure of macrophage activation. We tested this hypothesis with mice rendered immunodeficient by selective depletion of CD4+ lymphocytes and inoculated intratracheally with P. carinii. After aerosol administration of recombinant murine gamma interferon, the intensity of P. carinii infection in these mice was reduced in comparison with that in mice not treated with gamma interferon. Histologic scoring of lung tissue did not reveal additional pulmonary inflammation attributable to gamma interferon. Aerosol administration of gamma interferon may reduce the intensity of P. carinii infection by augmentation of host defense, despite persistent CD4+ lymphocyte depletion.