Interleukin-2 inhibits germinal center formation by limiting T follicular helper cell differentiation.

T follicular helper (Tfh) cells promote T cell-dependent humoral immune responses by providing T cell help to B cells and by promoting germinal center (GC) formation and long-lived antibody responses. However, the cellular and molecular mechanisms that control Tfh cell differentiation in vivo are incompletely understood. Here we show that interleukin-2 (IL-2) administration impaired influenza-specific GCs, long-lived IgG responses, and Tfh cells.

DAP10 contributes to CD8(+) T cell-mediated cytotoxic effector mechanisms during Mycobacterium tuberculosis infection.

The activating C-type lectin-like receptor NKG2D, which is expressed by mouse NK cells and activated CD8 T cells, was previously demonstrated to be involved in tumor rejection and as a defense mechanism against viral and bacterial infections. Because CD8 T cells are important for protective immune responses during chronic Mycobacterium tuberculosis (Mtb) infection and represent a promising target for new vaccine strategies to prevent human pulmonary tuberculosis (TB), we studied the immune response in mice deficient for the NKG2D adapter molecule DAP10 during experimental TB. After aerosol infection, DAP10-defcient mice displayed an unimpaired recruitment, activation and development of antigen-specific CD8 T cells.

Clonal expansions and loss of receptor diversity in the naive CD8 T cell repertoire of aged mice.

There are well-characterized age-related changes in the peripheral repertoire of CD8 T cells characterized by reductions in the ratio of naive:memory T cells and the development of large clonal expansions in the memory pool. In addition, the TCR repertoire of naive T cells is reduced with aging. Because a diverse repertoire of naive T cells is essential for a vigorous response to new infections and vaccinations, there is much interest in understanding the mechanisms responsible for declining repertoire diversity.

Uneven distribution of MHC class II epitopes within the influenza virus.

The identification of T cell epitopes is crucial for the understanding of the host immune response during infection. While much is known about the MHC class I-restricted response following influenza virus infection of C57BL/6 mice, with over 16 CD8 epitopes identified to date, less is known about the MHC class II-restricted response. Currently, only a few I-A(b)-restricted T helper epitopes have been identified.

Concurrent outbreak of multidrug-resistant and susceptible subclones of Acinetobacter baumannii affecting different wards of a single hospital.

Background And Objective: Acinetobacter baumannii has emerged as an opportunistic pathogen among acutely ill patients, especially those with thermal injury. A prospective 8-month study was conducted to describe the clinical and molecular epidemiology of multidrug-resistant A. baumannii affecting a single hospital.

Evaluation of dual-labeled fluorescent DNA probe purity versus performance in real-time PCR.

Real-time PCR technology using dual-labeled fluorescent oligonucleotide probes allows for sensitive, specific, and quantitative determination of mRNA or DNA targets. Historically, dual-labeled probes have been the most expensive reagent in real-time PCR because of the postsynthesis high-performance liquid chromatography (HPLC) and/or gel purification steps required due to limitations in traditional synthesis chemistry. The recent availability of quencher reagents that allow the 3' quencher incorporation as part of the on-machine synthesis has presented the possibility that probes, when carefully synthesized, may be used without extensive postsynthesis purification.

Regional occurrence of plasmid-mediated SHV-7, an extended-spectrum beta-lactamase, in Enterobacter cloacae in Philadelphia Teaching Hospitals.

Although the production of extended-spectrum beta-lactamases (ESBLs) by Klebsiella pneumoniae and Escherichia coli is an emerging problem, limited data are available regarding the frequency of ESBL production in other organisms. We provide the only description of regional occurrence of SHV-7 in Enterobacteriaceae other than E. coli or K.

Cutting edge: virus-specific CD4+ memory T cells in nonlymphoid tissues express a highly activated phenotype.

Recent studies have shown that CD4(+) memory T cells persist in nonlymphoid organs following infections. However, the development and phenotype of these peripheral memory cells are poorly defined. In this study, multimerized MHC-Ig fusion proteins, with a covalently attached peptide sequence from the Sendai virus hemagglutinin/neuraminidase gene, have been used to identify virus-specific CD4(+) T cells during Sendai virus infection and the establishment of peripheral CD4(+) memory populations in the lungs.

Exploring the role of amino acid-18 of the leucine binding proteins of E. coli.

Two periplasmic binding proteins of E. coli, the leucine specific-binding protein (LS) and leucine-isoleucine-valine binding protein (LIV), have high similarity in their structure and function, but show different substrate specificity. A key difference between these proteins is residue 18 in the binding pocket, a tryptophan residue in the LS and a tyrosine residue in the LIV.

Strategies for genotyping: Effectiveness of tailing primers to increase accuracy in short tandem repeat determinations.

A problem associated with automated analysis of fluorescently labeled fragments separated by slab gel or capillary electrophoresis is the doublet peak formed when Taq DNA Polymerase adds a nontemplated nucleotide (generally an adenosine) to the 3' end of the product.This nontemplated addition (plus A) is primarily dependent on the 5' sequence of the reverse primer and, to a lesser extent, polymerase chain reaction (PCR) conditions. Primers may amplify the true product, the plus A product or a doublet product comprised of both.