(MHC) class I molecules are polymorphic cell surface glycoproteins that play an essential role in immune surveillance. In the MHC class I antigen presentation pathway, peptides derived from cytosolic proteasome-mediated proteolysis are transported into the endoplasmic reticulum (ER) via the transporter associated with antigen processing (TAP), reviewed in ref. 1. In the ER lumen, translocated p...

CD8(+) T cells respond to signals mediated through a specific interaction between the T-cell receptor (TCR) and a composite antigen in the form of an epitopic peptide bound between the polymorphic α1 and α2 helices of an MHC class I (MHCI) molecule. The CD8 glycoprotein 'co-receives' antigen by binding to an invariant region of the MHCI molecule and can enhance ligand recognition by up to 1 mil...

Analysis of the tissue-specific expression of the Q5k gene in the AKR mouse reveals an unusual expression pattern. The Q5k mRNA is present in embryos from day 12, but expression is switched off in most tissues except thymus and testis shortly after birth. Late in pregnancy the gene is again transcribed in females. Analysis at the epitope level, with a Qa-2 specific monoclonal antibody revealed ...

A critical molecular interaction during assembly of the major histocompatibility complex (MHC) class I molecules takes place between the heavy chain and the transporter-associated with antigen-processing (TAP) complex. The recent mapping of regions of the heavy chain involved in the binding to TAP suggests a complex molecular interaction essential for the cell surface expression of the MHC clas...

PROBLEM The regulatory mechanisms governing differential expression of classical major histocompatibility complex (MHC) class I (MHC-Ia) and non-classical MHC class I (MHC-Ib) genes are poorly understood. METHOD OF STUDY Quantitative reverse transcription- polymerase chain reaction (PCR) was used to compare the abundance of MHC-I transcripts and related transcription factors in peripheral blo...

We isolated major histocompatibility complex (MHC)-specific viral peptides from cells infected with influenza virus in the continuous presence of the drug brefeldin A, which blocks exocytosis of newly synthesized MHC class I molecules. MHC-specific peptides were also isolated from cells expressing mouse Kd class I MHC molecules whose cytoplasmic domain was substituted by that of the adenovirus ...

Presentation of MHC class I-restricted peptides by dendritic cells (DCs) can elicit vigorous antigen-specific CTL responses in vivo. It is well established, however, that T cell help can augment CTL function, raising the question of how best to present tumor-associated MHC class I epitopes to induce effective tumor immunity. To this end, we have examined the role of MHC class II peptide-complex...

T cell tolerance depends on the T cell receptor's affinity for peptide/major histocompatibility complex (MHC) ligand; this critical parameter determines whether a thymocyte will be included (positive selection) or excluded (negative selection) from the T cell repertoire. A quantitative analysis of ligand binding was performed using an experimental system permitting receptor-coreceptor interacti...

Major histocompatibility complex (MHC) class I molecules are heterotrimers consisting of a polymorphic H chain, beta 2-microglobulin (beta 2m) and peptide. Peptides are thought to associate early during biosynthesis but the order of assembly of class I molecules from their component subunits in intact cells is not settled. We have studied the assembly of MHC class I molecules in intact cells wi...

Natural killer (NK) cell-mediated lysis is negatively regulated by killer cell inhibitory receptors specific for major histocompatibility complex (MHC) class I molecules. In this study, we characterize a novel inhibitory MHC class I receptor of the immunoglobulin-superfamily, expressed not only by subsets of NK and T cells, but also by B cells, monocytes, macrophages, and dendritic cells. This ...