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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-γ (IFN-γ)-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-γ, 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-γ concentrations correlated with neopterin levels and tryptophan degradation. Proliferative responses to PHA and PWM cytokine were lower in HIV patients, with IFN-γ formation predicting proliferative responses. Higher mRNA expression of IFN-γ, GCH-I and IDO after 6 h was related to better proliferative responses in HIV-infected PBMCs. In conclusion, induction of IFN-γ 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. [ABSTRACT FROM AUTHOR]

Abstract: We report five consecutive cases of Anaplasma (A.) phagocytophilum infection (the causative agent of human granulocytic anaplasmosis (HGA)) from western Austria. All infections were acquired between June and August in 2003 and 2004 in the Inn valley (Tyrol, Austria). Four patients required hospitalisation, one patient was treated as an outpatient. During the acute stage of illness, laboratory findings included thrombocytopenia (5/5), elevated C-reactive protein (5/5), elevated neopterin (5/5), elevated lactate dehydrogenase (4/5), and elevation of liver enzymes (4/5). Leukopenia (3/5) and elevated procalcitonin (2/5) were less frequently observed. All patients were treated with tetracyclines, which led to prompt improvement of the clinical conditions. Anti-platelet antibodies were observed in one of four patients, but remained unchanged after complete covalescence. [Copyright &y& Elsevier]

Abstract: Design: We evaluated whether an increase in haemoglobin levels in the first 6 months of effective anti-retroviral therapy (ART) is associated with a decrease in immune activation. To reduce confounding factors only men (n = 35) and patients not receiving agents known to enhance haematopoiesis or patients without diseases that might suppress haematopoiesis were included. Simultaneously parameters of iron metabolism and cofactors for haematopoiesis were analysed. Results: A median baseline haemoglobin level of 139 g L-1 increased to 149 g L-1 at month 6 of ART (P < 0.001). At baseline low haemoglobin levels were strongly associated with high neopterin concentrations (r = - 0.64, P < 0.001), and much less correlated to high HIV-1 RNA levels (r = - 0.41, P < 0.05) and to a lower CD4+ cell count (r = 0.33, P < 0.05). The change of neopterin levels during the study period correlated with the relative change in haemoglobin levels, r = - 0.35, P = 0.03, whereas no such correlations were found for the change of HIV-1 RNA levels and the CD4 cell count. A logistic regression analysis revealed that the change of neopterin and soluble transferrin receptors concentrations are independently associated with an increase of haemoglobin levels of more than 15 g L-1 . Conclusion: Our study supports a cause–effect relationship between immune activation and anaemia in HIV-infected patients. Treatment of patients with ART decreases virus load, which may thereby result in silencing of immune effector activity thus ameliorating anaemia by reversing the anti-proliferative effects of cytokines towards erythroid progenitors and the iron withdrawal strategy of the immune system. [ABSTRACT FROM AUTHOR]

Vaccination against seasonal influenza is recommended for all HIV-infected persons. Few data have been reported on the effect of repeated annual vaccination in this population. We measured haemagglutination inhibition antibody responses and investigated seroprotection rates in 344 HIV-infected adults before and 12 weeks after influenza vaccination with a trivalent subunit vaccine. 68.3% of patients were male, the median age was 45 years. 83.7% had a viral load < 50 copies/mL. The median CD4 count was 604/µL. 304 patients (88.4%) had received influenza vaccinations in previous years. Seroprotection rates for A/H1N1 and B were over 90% in all age groups before vaccination and close to 100% after vaccination. For A/H3N2, seroprotection rates were lowest in individuals below 30 years both before and after vaccination (22.2% and 50.0%) and higher in older age groups (48.4% and 83.9% in people over 60 years). GMT fold increases were not significantly different across the age groups (3.0 to 4.2, p = 0.425). Previous influenza vaccinations were associated with higher seroprotection rates before and after vaccination (62.2% and 84.2% in patients with 8 or more previous vaccinations vs. 15.0% and 57.5% without previous vaccinations, respectively). Individuals with detectable viral load, elevated immune activation (urine neopterin ≥ 250 µmol/mol creatinine), and higher CD4 nadir (≥200 cells/µL) showed a trend towards inferior immune responses to vaccination, whereas gender and CD4 count did not have an effect. The lower seroprotection rates observed in younger individuals may be explained by the higher proportion of patients without HIV treatment and with fewer previous encounters with influenza strains. Good seroprotection rates can be achieved in elderly HIV-infected patients and after repeated annual vaccinations. [ABSTRACT FROM AUTHOR]

The article investigates the plasma of patients through interferon-y-mediated pathways and evaluates for associations with the proliferative responses of Peripheral Blood Mononuclear Cells (PBMCs) to mitrogens in vitro. Result shows that the in vitro proliferative capacity of PBMC was associated with viral load, CD4 counts and also tryptophan degradation. It was then concluded that the higher the degree of immune activation in vivo, the lower is the proliferative capacity of PBMC in vitro.

Abstract: Objective: Higher blood levels of the essential amino acid phenylalanine (phe) have been documented in patients with HIV-1 infection. They may relate to a diminished conversion of phe to tyrosine (tyr) by the enzyme phenylalanine-hydroxylase (PAH). PAH is rate-limiting in the biosynthesis of dopamine, and impaired PAH activity is reflected by an increased phe to tyr ratio (phe/tyr). Methods: Plasma phe/tyr was measured in 107 patients with HIV-1 infection before and after 12months of effective antiretroviral therapy (ART). Results were compared with CD4+ cell counts, HIV-1 RNA levels and concentrations of immune activation marker neopterin. Results: Before ART, phe/tyr was mean±S.D.: 0.99±0.57μmol/μmol. Phe/tyr correlated significantly with plasma and urine neopterin concentrations (rs =0.434, and rs =0.392; both p <0.001) and less strongly with HIV-RNA levels (rs =0.173) and CD4+ counts (rs =−0.182, both p <0.05). After ART, phe/tyr dropped to 0.72±0.16 (=−27%; U =5.21, p =0.01) which was due to an average decline of −14% of phe concentrations from 73.1±34.0μmol/L at baseline to 62.9±17.8μmol/L after ART (U =2.51, p =0.01) and a concomitant increase of tyr concentrations (+13%, U =2.46, p =0.01). In parallel, significant reductions of plasma and urine neopterin concentrations were observed during ART. Conclusions: Increased phe/tyr is frequent in patients with HIV-1 infection and is related to immune activation. ART was found to decrease phe/tyr and this change could indicate and influence on PAH activity. Future studies might be able to show whether the decline of phe/tyr under ART may concur with the often improved neuropsychiatric status in treated patients. [Copyright &y& Elsevier]

Antiretroviral therapy (ART) has a significant impact on HIV-1 RNA levels, the CD4 cell count, and immune activation. We examined whether these changes are associated with a change in the rate of tryptophan degradation (expressed as the kynurenine to tryptophan ratio, kyn/trp) as an estimate for the activity of interferon-γ inducible enzyme indoleamine (, )-dioxygenase (IDO). Plasma levels of tryptophan, kynurenine, and neopterin were measured pretherapy and 6 months postinitiation of therapy in 45 patients with HIV-1 RNA levels of less than 1000 copies/ml 6 months after initiation of ART. Before ART, the patients had decreased tryptophan and increased kynurenine concentrations compared to healthy controls. During ART, average tryptophan levels increased; in the same time kynurenine and kyn/trp decreased (P < 0.001), although not to normal levels. Since pretherapy tryptophan concentrations correlated inversely with neopterin, and kynurenine correlated with viral load and neopterin but not with CD4 cell count, the data support the view that HIV production may induce immune activation and consequently tryptophan is degraded at a higher rate. In agreement, kyn/trp positively correlated with neopterin (rs = 0.60, P < 0.001), with virus load (rs = 0.37, P = 0.013), and very weakly with CD4+ cells counts (rs = 0.30, P = 0.049). The change in the kyn/trp ratio during ART correlated more strongly with the change in neopterin levels (rs = 0.49, P = 0.001) than with the change in HIV RNA levels and weakly with the CD4 cell count. The data underscore the fact that both neopterin production and tryptophan degradation are triggered by immune activation. Tryptophan degradation is increased in HIV infection and partially reversed under ART. The data agree with the concept that immune activation is the common background of IDO activation which may be an important factor underlying T-cell hyporesponsiveness. [Copyright &y& Elsevier]