Naturally Occurring Fc-Dependent Antibody From HIV-Seronegative Individuals Promotes HIV-Induced IFN-α Production.

A majority of adults without HIV infection and with a low risk of HIV-exposure have plasma IgG antibodies that enhance the rate and magnitude of HIV-induced interferon alpha (IFN-α) production. Fc-dependent IgG-HIV complexes induce IFN-α rapidly and in high titers in response to HIV concentrations that are too low to otherwise stimulate an effective IFN-α response. IFN-α promoting antibody (IPA) counters HIV-specific inhibition of IFN-α production, and compensates for the inherent delay in IFN-α production common to HIV infection and other viruses. Naturally occurring IPA has the potential to initiate a potent IFN-α response early in the course of HIV mucosal invasion in time to terminate infection prior to the creation of a pool of persistently infected cells. The current study adds IPA as a mediator of an Fc-dependent antiviral state capable of preventing HIV infection.

Cumulative False-Positive QuantiFERON-TB Interferon-γ Release Assay Results.

RATIONALE: Despite reports of unreliability, the QuantiFERON-TB interferon-γ release assay is increasingly used for the annual screening of individuals at risk for latent tuberculosis. Continued use of the QuantiFERON-TB assay suggests the need for more definitive evidence of its reproducibility and accuracy. OBJECTIVES: To examine reproducibility and the accumulation of false-positive test results when the QuantiFERON-TB is repeated annually and to examine the validity of confirming positive test results with the performance of a second QuantiFERON-TB. METHODS: We performed a retrospective, longitudinal evaluation of results from serial screening of a cohort of emergency responders from 2001 to 2013. MEASUREMENTS AND MAIN RESULTS: Results of tuberculin tests and QuantiFERON-TB tests performed annually as part of a mandated first responder examination were retroactively reviewed. In this population, positive results occurred in new individuals each year. QuantiFERON-TB results were positive in 80 of 557 tuberculin test-negative individuals examined annually for a maximum of 7 years. Only 10 individuals with initially positive results remained positive when the test was repeated the next year, and 9 of these 10 were QuantiFERON-TB-negative within 3 years. The number of individuals with a positive result increased annually, and, after 7 years, 32 (27.4%) of 117 people had a positive result. CONCLUSIONS: When viewed in the context of the extensive literature documenting unreliable QuantiFERON-TB test performance, our findings of frequent, cumulative, sporadic, and irreproducible positive results support discontinuing the use of the QuantiFERON-TB assay for the diagnosis of latent tuberculosis in low-risk populations.

Immune-specific immunoglobulin G-mediated enhancement of human immunodeficiency virus-induced IFN-alpha production.

Interferon-alpha (IFN-alpha) is synthesized as an integral part of innate immunity to viral infection. We previously provided preliminary evidence that antibody-containing serum from HIV-infected individuals enhanced HIV-induced production of IFN-alpha. Subsequently, preparations of pooled human immunoglobulin G (IgG) have also been shown to enhance poliovirus (PV)-induced IFN-alpha production. The current work establishes IgG as the serum mediator that enhances induction of IFN-alpha by HIV. Our studies also establish the ability of sera from individual subjects to enhance PV-induced IFN-alpha production. HIV-induced IFN-alpha production was enhanced maximally by >4000-fold and by an average of 25-fold. Sera from 74 people enhanced PV- induced IFN-alpha from undetectable levels to an average of 615 units (range 7-4679 units). The ability of individual sera to enhance IFN-alpha production by HIV and PV persisted undiminished in patients with AIDS. IgG-mediated enhancement of IFN-alpha production was similar to that induced by IgG and PV and was blocked by IgG Fc fragments. Demonstration of the selective enhancement of HIV-induced IFN-alpha production by IgG from HIV-seropositive individuals provides further evidence for the existence of antigen-specific upregulation of a critical component of innate antiviral immunity by the adaptive Th2 immune response.

Prevalence of osteoporosis in men in a VA rehabilitation center.

OBJECTIVE: To evaluate the prevalence of previously unrecognized osteoporosis in men admitted for long-term rehabilitation nursing home care. DESIGN: Cross-sectional study. METHODS: A total of 1179 consecutive admissions to a VA rehabilitation center were reviewed. Men who were already diagnosed with osteoporosis, had confounding medical illness, were unable to complete the study, or who declined to participate were excluded. A total of 153 patients were enrolled and 106 were evaluated. Measurements included dual-energy X-ray absorptiometry of the hip and lumbar spine, biochemical and hormonal studies, and functional evaluation. RESULTS: A total of 33 patients (31.1%) had osteoporosis (T-score at any site lumbar spine, total hip, or femoral neck <-2.5). Patients with osteoporosis were significantly older than those without: 68.4 +/- 13.2 years versus 62.7 +/- 12.1 years (P <.05), respectively. Body mass index (BMI) and weight were lower in men with osteoporosis: 23.4 +/- 3.9 kg/m2 versus 28.7 +/- 7.08 kg/m2 and 72.6 +/- 14.4 kg versus 90.3 +/- 23.8 kg, respectively (both, P <.001). There were no differences in use of medications thought to affect bone metabolism or functional status, or in hormonal and metabolic measurements. Hip and spine bone density were correlated (r = 0.3, P <.05). Multivariate analysis showed that hip bone density was independently associated with BMI. CONCLUSION: Hip osteoporosis is common in this unscreened population, suggesting that screening should be more widely performed in veterans admitted to rehabilitation units. These data suggest that nutritional status could impact osteoporosis risk.

IgG-derived Fc down-regulates virus-induced plasmacytoid dendritic cell (pDC) IFNalpha production.

Interferon alpha (IFNalpha) produced primarily by plasmacytoid dendritic cells (pDC) is a potent component of the anti-viral innate immune response, and modulates adaptive immunity. Primary control of IFNalpha production occurs at a cellular level and is highly dependent upon regulatory factors and their products. Recent studies have identified up-regulation of IFNalpha production mediated by the adaptive immune response in the form of immune specific IgG. These studies establish a role for the external control of IFNalpha production. The current work demonstrates that the Fc portion of IgG is a potent inhibitor of IFNalpha produced by pDCs in response to HIV, HSV, and VSV. Fc down-regulation occurs after IFNalpha production can be detected by bioassay, and suggests the existence of late regulatory events in the control of IFNalpha production. Down-regulation of IFNalpha is not caused by Fc-induced necrosis, apoptosis or neutralization of IFNalpha activity. Demonstration of Fc-mediated down-regulation of IFNalpha provides additional evidence of the role of IgG in the regulation of IFNalpha production.

EST-based gene discovery in pig: virtual expression patterns and comparative mapping to human.

A molecular understanding of porcine reproduction is of biological interest and economic importance. Our Midwest Consortium has produced cDNA libraries containing the majority of genes expressed in major female reproductive tissues, and we have deposited into public databases 21,499 expressed sequence tag (EST) gene sequences from the 3' end of clones from these libraries. These sequences represent 10,574 different genes, based on sequence comparison among these data, and comparison with existing porcine ESTs and genes indicate as many as 4652 of these EST clusters are novel. In silico analysis identified sequences that are expressed in specific pig tissues or organs and confirmed the broad expression in pig for many genes ubiquitously expressed in human tissues. Furthermore, we have developed computer software to identify sequence similarity of these pig genes with their human counterparts, and to extract the mapping information of these human homologues from genome databases. We demonstrate the utility of this software for comparative mapping by localizing 61 genes on the porcine physical map for Chromosomes (Chrs) 5, 10, and 14.