Biomedical subjects

Donald D Anthony

Publications and source records attributed to Donald D Anthony.

7 recordsLinked to original sources

PubMed2006

HIV coinfection impairs CD28-mediated costimulation of hepatitis C virus-specific CD8 cells.

BACKGROUND: During human immunodeficiency virus (HIV) infection, reduced proportions of CD8 cells express CD28, the key costimulatory molecule for lymphocyte activation. However, it is unclear whether reduced CD28 expression affects immune responses to non-HIV antigens, potentially contributing to susceptibility to opportunistic infection. METHODS: We measured CD4- and CD8-specific interferon- gamma responses to hepatitis C virus (HCV) peptide pools in subjects with chronic HCV monoinfection (n=14), in subjects with chronic HCV/HIV coinfection (n=15), and in healthy control subjects (n=10) by enzyme-linked immunospot assay in the presence and absence of CD28 costimulation. RESULTS: Anti-CD28 agonist increased the cumulative frequency of HCV-specific CD4 cell responses in the subjects with HCV monoinfection and in those with HCV/HIV coinfection. In contrast, anti-CD28 agonist increased the breadth and cumulative frequency of HCV-specific CD8 cell responses only in the subjects with HCV monoinfection. Additionally, in the presence of anti-CD28 agonist, the proportion of subjects responding, the cumulative frequency, and the breadth of reactive CD8 cells were greater among the subjects with HCV monoinfection than among those with HCV/HIV coinfection. Finally, the HCV/HIV-coinfected subjects had lower proportions of CD8 cells that expressed CD28. CONCLUSIONS: These results indicate that, during HCV/HIV coinfection, memory-effector CD8 cells have reduced responsiveness to CD28 costimulation. This appears to reflect a global effect that HIV has on the activation or differentiation state of CD8 cells that are responsive to other microbial pathogens. This functional defect has implications for the pathogenesis of HCV/HIV coinfection.

Adult↗

PubMed2005

Phenotypic and functional analysis of EBV-specific memory CD8 cells in SLE.

T cell dysfunction has been described in systemic lupus erythematosus (SLE). However, the specific phenotype and function of antigen-specific CD8 cells is less clear. Here we determined phenotype and function of Epstein-Barr virus (EBV)-specific CD8 cells at the single-cell level in SLE. HLA-A2-restricted EBV-BMLF-1-specific CD8 cells were enumerated by flow cytometry using tetramers in SLE and healthy control subjects. Antigen-specific CD8 cells were analyzed for expression of differentiation, activation, proliferation, and anti-apoptotic markers. EBV-specific, other virus-specific (specific against a viral peptide pool consisting of cytomegalovirus, EBV and influenza virus peptides), and mitogen-induced CD8 cell function was assessed by INF-gamma ELISPOT assay. Frequencies of EBV-specific CD8 cells tended to be greater in SLE subjects than in healthy control subjects (p=0.07). While over 10% of EBV-specific CD8 cells were capable of producing IFN-gamma in four out of five healthy control subjects, such proportions of EBV-specific CD8 cells capable of IFN-gamma production were observed in only one out of six SLE subjects (p=0.04). In contrast, viral peptide pool-specific and mitogen-induced IFN-gamma-producing T cell function was intact in SLE subjects. Phenotypic analysis revealed EBV-specific CD8 cells to be in an early to intermediate differentiation and resting memory state in both groups. While EBV-specific CD8 cells are similar in phenotype, their frequency tends to be increased, and function appears to be decreased in SLE. Therefore, an impaired EBV-specific CD8 immune response may exist in SLE, potentially contributing to disease pathogenesis.

Adult↗

PubMed2004

Selective impairments in dendritic cell-associated function distinguish hepatitis C virus and HIV infection.

Impaired APC functions may play important roles in chronicity of hepatitis C virus (HCV) and HIV infections. To investigate the separate and combined effects of HCV and HIV infection on immature dendritic cells (DCs), we evaluated myeloid-derived DC (MDC) and plasmacytoid-derived DC (PDC) frequencies and functions, measured by Toll-like receptor ligand-induced IFN-alpha and IL-12, in healthy controls and subjects with chronic HCV, HIV, and HCV-HIV infection. To evaluate the relation between innate and adaptive immunity, we measured HCV-specific IFN-gamma-producing T cell frequency. MDC frequencies tended to be reduced in HIV infection (1.8-fold), while PDC frequencies were minimally reduced in HCV infection (1.4-fold). In contrast, a striking reduction in non-PDC-associated IFN-alpha production was observed in HIV-infected subjects (17-fold), while PDC-associated IFN-alpha production was markedly reduced in HCV-infected subjects (20-fold). Both non-PDC and PDC functions were impaired in HCV-HIV coinfection. MDC-associated IL-12 production was markedly reduced in both HCV and HIV-infected subjects (over 10-fold). Functional defects were attenuated with slowly progressive HIV infection. The proportion of subjects with HCV-specific T cell responses, and the number of Ags recognized were reduced in HCV-HIV subjects as compared with HCV singly infected subjects. A positive association was observed between MDC-associated IL-12 production and HCV-specific T cell frequency in HCV-infected subjects. These results indicate that immature DC function is dysregulated in HIV and HCV infections, but differentially, and that these defects are attenuated in slowly progressive HIV infection. These selectively different impairments may contribute to the reduced adaptive immune response to HCV in HCV-HIV coinfection.

CD4-Positive T-Lymphocytes↗

PubMed2004

CD28 costimulation enhances the sensitivity of the ELISPOT assay for detection of antigen-specific memory effector CD4 and CD8 cell populations in human diseases.

The frequencies of antigen-specific memory cells are often low in chronic disease states related to infection and autoimmunity, making detection of such populations difficult, even with high sensitivity assays such as the cytokine enzyme-linked immunospot (ELISPOT). The spectrum and function of antigen presenting cells (APC) in the peripheral compartment can differ considerably from the inflamed target organ. In order to approximate the costimulatory environment of the target organ, we measured T cell responses with and without the addition of agonistic anti-CD28 antibody in the ELISPOT assay. CD4 and CD8 IFN-gamma responses to viral (hepatitis C) and autoimmune antigens (islet cell) were tested in 10 hepatitis C and 8 type 1 diabetic as well as healthy control subjects. IFN-gamma responses to tetanus toxoid, mumps and cytomegalovirus (CMV) protein antigen, as well as Epstein-Barr virus and CMV peptides were also measured in healthy control subjects. We found higher frequencies of T cells reactive to protein and peptide antigens when anti-CD28 antibody was present, often detecting responses only in the presence of anti-CD28 antibody. These results demonstrate that anti-CD28 antibody signal enhanced ELISPOT assays can facilitate the identification of low precursor frequency T cells in chronic infectious and autoimmune disease states where suboptimal costimulatory environment may exist in the periphery. The use of such costimulation may also enable a more quantitative assessment of circulating memory effector T cell frequency.

Antigens, Viral↗

PubMed2003

T-cell epitope mapping using the ELISPOT approach.

The ELISPOT assay is particularly well suited to measure both clonal size and effector function of low-frequency antigen-specific T-cell populations directly ex vivo. Typically, an ELISPOT assay is performed with a freshly obtained sample (or cryopreserved sample) using less than 24h of culture. Additionally, this assay allows for the simultaneous analysis of hundreds of variables in parallel from a single tissue specimen. Because of these capabilities, this assay has found widespread use in the context of direct ex vivo immune diagnostic monitoring in humans. Herein we describe the rationale, methodology, and useful hints for performing T-cell epitope mapping using ELISPOT analysis, and review typical results of such an analysis.

Epitope Mapping↗

PubMed2002

HIV long-term non-progressors maintain brisk CD8 T cell responses to other viral antigens.

OBJECTIVE: To examine the specificity of heightened CD8 cell responses in HIV-1-infected long-term non-progressors. DESIGN: Cross-sectional study examining CD8 cell responses to hepatitis C virus (HCV) peptides in HCV-HIV LTNP (n = 6), HCV-HIV progressors (n = 11), HCV singly infected patients (n = 32), HCV singly infected patients with self-limited disease (n = 10), HIV singly infected progressors (n = 7) and HCV-negative, HIV-negative controls (n = 10). METHODS: The frequency of HCV-reactive interferon gamma-producing cells in peripheral blood was assayed by enzyme linked immunospot assay using a panel of 61 HCV-1-derived peptides. RESULTS: Five of six HCV-HIV LTNP had HCV-specific CD8 responses. In contrast, responses were observed in 2 of 32 HCV singly infected patients, 2 of the 10 HCV singly infected patients with self-limited disease, and 0 of 11 HCV-HIV progressors (P < 0.001). Both frequency of HCV-specific CD8 cells and number of HCV peptides recognized were greater in HCV-HIV LTNP than in other groups. CONCLUSIONS: HIV-infected LTNP maintain heightened CD8 cell responses to HCV in addition to heightened HIV specific responses. Common mechanisms may underlie preservation of CD8 immune responses in these individuals. An improved understanding of these mechanisms will help to gain insight into protective antiviral immunity as well as to the means whereby these viruses impair host defenses.

AIDS-Related Opportunistic Infections↗

PubMed2002

Comprehensive determinant mapping of the hepatitis C-specific CD8 cell repertoire reveals unpredicted immune hierarchy.

While CD8 cells are thought to play an important role in the control hepatitis C infection, low frequencies of virus-specific cells and high numbers of potential determinants have made it challenging to obtain direct and comprehensive data regarding fine specificity and clonal size of the CD8 cells involved. Most assays suited for measuring CD8 cell frequencies require prior knowledge of immune dominant peptides. While there are excellent algorithms for predicting MHC-peptide binding strength for particular class I alleles, it is unknown how accurate these algorithms are in predicting the actual determinant recognized in an individual coexpressing other class I alleles. We used a high throughput ELISPOT approach to test for responses to every possible 9-mer determinant within the 191 residue hepatitis C core protein in addition to 61 previously defined CD8 cell determinants. The amino acid sequence of each determinant recognized was compared with HLA-binding predictions for the expressed class I alleles. These data show feasibility for and importance of comprehensive direct ex vivo monitoring, an approach which should facilitate design of antiviral immunotherapeutic strategies.

Algorithms↗