Antigen

About: Antigen is a research topic. Over the lifetime, 170233 publications have been published within this topic receiving 6982342 citations. The topic is also known as: antibody generator & Antigen.

Lineage commitment in the immune system: the T helper lymphocyte grows up

Abstract: Cells of the immune system provide particularly fruitful subjects for the study of lineage commitment. Both T and B lymphocytes undergo complicated patterns of differentiation from uncommitted, nonfunctional precursor cells to highly sophisticated effector cells. The development of the helper T lymphocyte is one of the most elegant examples of this. A little over a decade ago, Mosmann and Coffman (1989) discovered that naive mouse CD4 T helper lymphocytes, upon receiving an antigenic stimulus, differentiate into two distinct subsets defined both by their function and by unique cytokine profiles. These subsets, T helper 1 (Th1) and T helper 2 (Th2) (Mosmann et al. 1986; Mosmann and Coffman 1989; Paul and Seder 1994; O’Garra 1998; Rengarajan and Glimcher 2000), are responsible for cell-mediated/inflammatory immunity and humoral responses, respectively (Fig. 1). This division of labor fits nicely with previous demonstrations that an organism tends to mount either a cell-mediated or humoral response, but not both, in response to pathogens. The function of T helper cells can largely be explained by the cytokines they secrete. Cytokines (or lymphokines) are small hormone-like polypeptides that have pleiotrophic biological activities in several cell types. Resting T cells do not transcribe cytokine genes, but they are rapidly induced upon coactivation through the T-cell receptor (TCR) and costimulatory receptors (Lenschow et al. 1996). Much progress has been made in identifying the signaling pathways and transcription factors that control Th1 and Th2 differentiation as shown schematically (Fig. 2a). This review will summarize what is currently known about the signals that regulate lineage commitment in T helper cells with a special focus on three subset-specific transcription factors, T-bet, GATA-3, and c-Maf, responsible for lineage commitment (Fig. 2b).

Enzyme-labeled antibodies for the light and electron microscopic localization of tissue antigens

Abstract: Enzymes, either acid phosphatase or horseradish peroxidase, were conjugated to antibodies with bifunctional reagents. The conjugates, enzymatically and immunologically active, were employed in the immunohistochemical localization of tissue antigens utilizing the reaction product of the enzymatic reaction as the marker. Tissues reacted with acid phosphatase-labeled antibodies directed against basement membrane were stained for the enzyme with Gomori's method, and those reacted with peroxidase-labeled antibody were stained with Karnovsky's method. The reaction products of the enzymes localized in the basement membrane. Unlike the preparations of the fluorescent antibody technique, enzyme-labeled antibody preparations were permanent, could be observed with an ordinary microscope, and could be examined with the electron microscope. In the latter, specific localization of antibody occurred in the basement membrane and in the endoplasmic reticulum of cells known to synthesize basement membrane antigens. The method is sensitive because of the amplifying effect of the enzymatic activity. The ultrastructural preservation and localization were better with acid phosphatase-labeled antibody than with peroxidase-labeled antibody, but acid phosphatase conjugated antibody was unstable and difficult to prepare. Peroxidase-antibody conjugates were stable and could be stored for several months at 4°C, or indefiniely in a frozen state.

Prostate Attenuated Replication Competent Adenovirus (ARCA) CN706: A Selective Cytotoxic for Prostate-specific Antigen-positive Prostate Cancer Cells

Abstract: Prostate-specific antigen (PSA) is a widely used marker for the diagnosis and management of prostate cancer Minimal enhancer/promoter constructs derived from the 5' flank of the human PSA gene (prostate-specific enhancer) were inserted into adenovirus type 5 DNA so as to drive the E1A gene, thereby creating a prostate-specific enhancer-containing virus, CN706 E1A was expressed at high levels in CN706-infected human PSA-producing LNCaP cells but not in CN706-infected DU145 cells, which are human prostate cells that do not express PSA The titer of CN706 was significantly higher in LNCaP cells compared to several human cell lines that do not produce PSA (HBL100, PANC-1, MCF-7, DU145, and OVCAR3) Furthermore, in LNCaP cells, the yield of CN706 was dependent on exogenous androgen (R1881) CN706 destroyed large LNCaP tumors (1 x 10(9) cells) and abolished PSA production in nu/nu mouse xenograft models with a single intratumoral injection

Extreme Th1 bias of invariant Vα24JαQ T cells in type 1 diabetes

Abstract: Type 1 diabetes (insulin-dependent diabetes mellitus, IDDM) is a disease controlled by the major histocompatibility complex (MHC) which results from T-cell-mediated destruction of pancreatic beta-cells. The incomplete concordance in identical twins and the presence of autoreactive T cells and autoantibodies in individuals who do not develop diabetes suggest that other abnormalities must occur in the immune system for disease to result. We therefore investigated a series of at-risk non-progressors and type 1 diabetic patients (including five identical twin/triplet sets discordant for disease). The diabetic siblings had lower frequencies of CD4-CD8- Valpha24JalphaQ+ T cells compared with their non-diabetic sibling. All 56 Valpha24JalphaQ+ clones isolated from the diabetic twins/triplets secreted only interferon (IFN)-gamma upon stimulation; in contrast, 76 of 79 clones from the at-risk non-progressors and normals secreted both interleukin (IL)-4 and IFN-gamma. Half of the at-risk non-progressors had high serum levels of IL-4 and IFN-gamma. These results support a model for IDDM in which Thl-cell-mediated tissue damage is initially regulated by Valpha24JalphaQ+ T cells producing both cytokines; the loss of their capacity to secrete IL-4 is correlated with IDDM.