Mouse and human CD8+ CD28low regulatory T lymphocytes differentiate in the thymus

Regulatory T (Treg) lymphocytes play a central role in the control of immune responses and so maintain immune tolerance and homeostasis. In mice, expression of the CD8 co‐receptor and low levels of the co‐stimulatory molecule CD28 characterizes a Treg cell population that exerts potent suppressive function in vitro and efficiently controls experimental immunopathology in vivo. It has remained unclear if CD8⁺ CD28^low Treg cells develop in the thymus or represent a population of chronically activated conventional T cells differentiating into Treg cells in the periphery, as suggested by their CD28^low phenotype. We demonstrate that functional CD8⁺ CD28^low Treg cells are present in the thymus and that these cells develop locally and are not recirculating from the periphery. Differentiation of CD8⁺ CD28^low Treg cells requires MHC class I expression on radioresistant but not on haematopoietic thymic stromal cells. In contrast to other Treg cells, CD8⁺ CD28^low Treg cells develop simultaneously with CD8⁺ CD28^high conventional T cells. We also identified a novel homologous naive CD8⁺ CD28^low T‐cell population with immunosuppressive properties in human blood and thymus. Combined, our data demonstrate that CD8⁺ CD28^low cells can develop in the thymus of mice and suggest that the same is true in humans.     

The genes for cytochrome b,ND 4L,ND6 and two tRNAs from the mitochondrial genome of the locust,Locusta migratoria

We have cloned and characterized a 2,778-kb XbaI segment of the mitochondrial genome of the locust, Locusta migratoria. It harbours portions of the ND4 and the ND1 genes, the entire genes for ND6, ND4L and cytochrome b, and the genes for three mitochondrial tRNAs. The genes are arranged in an order which is conserved between orthopteran and dipteran insects. The analysis of the cytochrome b sequence, and its comparison with other systems, supports the current model structure for this polypeptide.     

Multimedia teaching software in university education

This article is aimed at developing of multimedia teaching programs. Authoring tool Authorware Professional for Windows is briefly described as a suited system for the developing of didactic applications. Author presents own application based on Authorware--Biophysics of perception of sound and light. At the end are also disscused benefits of multimedia teaching tools.     

The Molecular Mechanism of B Cell Activation by toll-like Receptor Protein RP-105

The B cell–specific transmembrane protein RP-105 belongs to the family of Drosophila toll-like proteins which are likely to trigger innate immune responses in mice and man. Here we demonstrate that the Src-family protein tyrosine kinase Lyn, protein kinase C β I/II (PKCβI/II), and Erk2-specific mitogen-activated protein (MAP) kinase kinase (MEK) are essential and probably functionally connected elements of the RP-105–mediated signaling cascade in B cells. We also find that negative regulation of RP-105–mediated activation of MAP kinases by membrane immunoglobulin may account for the phenomenon of antigen receptor–mediated arrest of RP-105–mediated B cell proliferation.     

The smoker's paradox in acute coronary syndrome: Is it real?

Introduction

Smoking is associated with atherosclerotic disease, but there is controversy about its protective nature after acute coronary syndrome (ACS).

Outbreak of serogroup C meningococcal disease caused by a variant of Neisseria meningitidis serotype 2a ET-15 in a community of men who have sex with men

We describe an outbreak, in a community of men who have sex with men, of serogroup C meningococcal disease caused by a genetic variant of the serotype 2a ET-15 Neisseria meningitidis characterized by a point mutation in the gene coding for the serotype 2a antigen. A microbiological characterization of the outbreak strain is presented in this report.