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Full-Text Articles in Medicine and Health Sciences

Survival Of Immunoglobulin G-Opsonized Toxoplasma Gondii In Nonadherent Human Monocytes., Camilo E. Fadul, Jacqueline Y. Channon, Lloyd H. Kasper Nov 1995

Survival Of Immunoglobulin G-Opsonized Toxoplasma Gondii In Nonadherent Human Monocytes., Camilo E. Fadul, Jacqueline Y. Channon, Lloyd H. Kasper

Dartmouth Scholarship

Toxoplasma gondii is a protozoan parasite that is able to penetrate human monocytes by either passive uptake during phagocytosis or active penetration. It is expected that immunoglobulin G (IgG) opsonization will target the parasite to macrophage Fc gamma receptors for phagocytic processing and subsequent degradation. Antibody-opsonized T. gondii tachyzoites were used to infect nonadherent and adherent human monocytes obtained from the peripheral blood of seronegative individuals. The infected monocytes were evaluated for the presence of intracellular parasites and the degree of parasiticidal activity. A marked difference in both the numbers of infected macrophages and numbers of parasites per 100 macrophages …


Survival Of Mouse Pancreatic Islet Allografts In Recipients Treated With Allogeneic Small Lymphocytes And Antibody To Cd40 Ligand., David C. Parker, Dale L. Greiner, Nancy E. Phillips, Michael C. Appel, Alan W. Steele, Fiona H. Durie, Randolph J. Noelle, John P. Mordes, Aldo A. Rossini Oct 1995

Survival Of Mouse Pancreatic Islet Allografts In Recipients Treated With Allogeneic Small Lymphocytes And Antibody To Cd40 Ligand., David C. Parker, Dale L. Greiner, Nancy E. Phillips, Michael C. Appel, Alan W. Steele, Fiona H. Durie, Randolph J. Noelle, John P. Mordes, Aldo A. Rossini

Dartmouth Scholarship

Combined treatment with allogeneic small lymphocytes or T-depleted small lymphocytes plus a blocking antibody to CD40 ligand (CD40L) permitted indefinite pancreatic islet allograft survival in 37 of 40 recipients that differed from islet donors at major and minor histocompatibility loci. The effect of the allogeneic small lymphocytes was donor antigen-specific. Neither treatment alone was as effective as combined treatment, although anti-CD40L by itself allowed indefinite islet allograft survival in 40% of recipients. Our interpretation is that small lymphocytes expressing donor antigens in the absence of appropriate costimulatory signals are tolerogenic for alloreactive host cells. Anti-CD40L antibody may prevent host T …


A Toxoplasma Gondii-Derived Factor(S) Stimulates Immune Downregulation: An In Vitro Model., Sakhina Haque, Azizul Haque, Lloyd H. Kasper Sep 1995

A Toxoplasma Gondii-Derived Factor(S) Stimulates Immune Downregulation: An In Vitro Model., Sakhina Haque, Azizul Haque, Lloyd H. Kasper

Dartmouth Scholarship

Suppression of the T-cell lymphoproliferative response and downregulation of interleukin 2 (IL-2) production by Toxoplasma gondii has been observed following in vivo infection. In this study, an experimental in vitro murine system was developed to evaluate the kinetics of these responses. Normal splenocytes from uninfected mice were stimulated with either concanavalin A or an anti-CD3 monoclonal antibody and cocultured with Toxoplasma tachyzoites either directly or separated by a transwell. A progressive decline in the lymphoproliferative response was observed as the concentration of parasites in culture increased. Neither heat-killed nor formaldehyde-fixed parasites stimulated this downregulatory response by the splenocytes. A decline …


A Novel Translational Regulation Function For The Simian Virus 40 Large-T Antigen Gene., Prithi Rajan, Sathyamagalam Swaminathan, Jiyue Zhu, Charles N. Cole Feb 1995

A Novel Translational Regulation Function For The Simian Virus 40 Large-T Antigen Gene., Prithi Rajan, Sathyamagalam Swaminathan, Jiyue Zhu, Charles N. Cole

Dartmouth Scholarship

Cells use the interferon-induced, double-stranded-RNA-dependent protein kinase PKR as a defense against virus infections. Upon activation, PKR phosphorylates and thereby inactivates the protein synthesis initiation factor eIF-2, resulting in the cessation of protein synthesis. Viruses have evolved various strategies to counteract this cellular defense. In this paper, we show that simian virus 40 (SV40) large-T antigen can antagonize the translational inhibitory effect resulting from the activation of PKR in virus-infected cells. Unlike the situation with other virus-host cell interactions, SV40 large-T antigen does not block the activation of PKR, suggesting that SV40 counteracts the cellular antiviral response mediated by PKR …