To examine potential age-specific adaptations in skeletal muscle size and myofiber contractile physiology in response to aerobic exercise, seven young (YM; 20 ± 1 yr) and six older men (OM; 74 ± 3 yr) performed 12 wk of cycle ergometer training. Muscle biopsies were obtained from the vastus lateralis to determine size and contractile properties of isolated slow [myosin heavy chain (MHC) I] and ...

The MHC class I (MHC-I) molecules ferry a cargo of peptides to the cell surface as potential ligands for CD8 + cytotoxic T cells. For nearly 20 years, the cargo has been described as a collection of short 8-9 mer peptides, whose length and sequences were believed to be primarily determined by the peptide-binding groove of MHC-I molecules. Yet the mechanisms for producing peptides of such optima...

MOTIVATION AND RESULTS Motivated by the ability of a simple threading approach to predict MHC I--peptide binding, we developed a new and improved structure-based model for which parameters can be estimated from additional sources of data about MHC-peptide binding. In addition to the known 3D structures of a small number of MHC-peptide complexes that were used in the original threading approach,...

Murine epidermal Langerhans cells were analyzed with fluorescence microscopy and multicolor flow cytometry for the surface expression of major histocompatibility complex (MHC) class I and class II antigens. Langerhans cells of H-2k haplotype were identified in situ or in epidermal-cell suspensions by their surface expression of the MHC class II determinants I-Ak and I-Ek. More than 90% of class...

Until recently, neurons in the healthy brain were considered immune-privileged because they did not appear to express MHC class I (MHCI). However, MHCI mRNA was found to be regulated by neural activity in the developing visual system and has been detected in other regions of the uninjured brain. Here we show that MHCI regulates aspects of synaptic function in response to activity. MHCI protein ...

This study examined the effect of the pro-inflammatory cytokines interferong (IFNg ) and tumor necrosis factora (TNFa ) on the induction of MHC class I–related genes in functionally mature brain neurons derived from cultures of dissociated rat hippocampal tissue. Patch clamp electrophysiology combined with single cell RT-PCR demonstrated that z 50% of the untreated neurons contained mRNA for MH...

In inflammatory reactions an increased expression of HLA class I and class II antigens is observed (1). This enhanced expression is expected to play a role in the activation of both MHC class Iand class II-restricted T cells. In vitro, the mediators interferon ,8 (IFN-0), tumor necrosis factor a (TNF-a), and IFN-y induce an increase in the MHC class I expression on human umbilical venal endothe...

COS7 (African Green Monkey kidney) cells stably transfected with the mouse MHC class I allele H-2K(b) were mutagenized, selected for low surface expression of endogenous MHC class I products, and subcloned. A mutant cell line, 4S8.12, expressing very low surface MHC class I (approximately 5% of parental levels) was identified. This cell line synthesized normal levels of the MHC class I H chain ...

Extensive polymorphism at the major histo-compatibility complex (MHC) is thought to confer immune protection on populations. A New World primate, the cotton-top tamarin (Saguinus oedipus), has a high prevalence of ulcerative colitis and adenocarcinoma of the colon and dies after infection with several human viruses. Lymphocytes from all animals tested expressed on common MHC class I allelic pro...

T cell recognition of peptide-MHC is highly specific and is sensitive to very low levels of agonist peptide; however, it is unclear how this effect is achieved or regulated. In this study we show that clustering class I MHC molecules on the cell surface of B lymphoblasts enhances their recognition by mouse and human T cells. We increased clustering of MHC I molecules by two methods, cholesterol...