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S Sanderson

Publications and source records attributed to S Sanderson.

8 recordsLinked to original sources
PubMed1995

Identification of a CD4+ T cell-stimulating antigen of pathogenic bacteria by expression cloning.

Identifying the immunogenic proteins that elicit pathogen-specific T cell responses is key to rational vaccine design. While several approaches have succeeded in identifying major histocompatibility complex (MHC) class I bound peptides that stimulate CD8+ T cells, these approaches have been difficult to extend to peptides presented by MHC class II molecules that stimulate CD4+ T cells. We describe here a novel strategy for identifying CD4+ T cell-stimulating antigen genes. Using Listeria monocytogenes-specific, lacZ-inducible T cells as single-cell probes, we screened a Listeria monocytogenes genomic library as recombinant Escherichia coli that were fed to macrophages. The antigen gene was isolated from the E. coli clone that, when ingested by the macrophages, allowed generation of the appropriate peptide/MHC class II complex and T cell activation. We show that the antigenic peptide is derived from a previously unknown listeria gene product with characteristics of a membrane-bound protein.

Amino Acid Sequence↗
PubMed1995

Expression of endogenous peptide-major histocompatibility complex class II complexes derived from invariant chain-antigen fusion proteins.

CD4+ T cells recognize major histocompatibility complex (MHC) class II-bound peptides that are primarily obtained from extracellular sources. Endogenously synthesized proteins that readily enter the MHC class I presentation pathway are generally excluded from the MHC class II presentation pathway. We show here that endogenously synthesized ovalbumin or hen egg lysozyme can be efficiently presented as peptide-MHC class II complexes when they are expressed as fusion proteins with the invariant chain (Ii). Similar to the wild-type Ii, the Ii-antigen fusion proteins were associated intracellularly with MHC molecules. Most efficient expression of endogenous peptide-MHC complex was obtained with fusion proteins that contained the endosomal targeting signal within the N-terminal cytoplasmic Ii residues but did not require the luminal residues of Ii that are known to bind MHC molecules. These results suggest that signals within the Ii can allow endogenously synthesized proteins to efficiently enter the MHC class II presentation pathway. They also suggest a strategy for identifying unknown antigens presented by MHC class II molecules.

Animals↗
PubMed1992

Detection of rare antigen-presenting cells by the lacZ T-cell activation assay suggests an expression cloning strategy for T-cell antigens.

The alpha/beta T-cell receptor a complex ligand formed by the association of antigenic peptides with molecules of the major histocompatibility complex (MHC). The inherent limitations of the conventional T-cell activation assays used to detect these peptide/MHC ligands have, until now, hampered the development of expression cloning systems for T-cell antigens. To overcome these limitations, we have recently introduced a method for detecting ligand-induced activation of individual T cells. This assay, which makes use of a lacZ reporter construct, differs from conventional ligand-induced activation assays in that it allows the detection of single, activated T cells in large pools of resting cells. We applied the lacZ assay to the problem of screening expression libraries, which requires the ability to detect ligand-bearing antigen-presenting cells when they are present at very low frequency. We show here that ligand-expressing antigen-presenting cells can be detected at frequencies of 1:10(3)-10(4), a level of sensitivity compatible with the screening of cDNA libraries. Furthermore, by using as antigen-presenting cells COS-7 cells stably transfected with the murine Kb class I MHC molecule, we demonstrate that transiently expressed ovalbumin is efficiently processed and presented to an ovalbumin/Kb-specific T-cell hybridoma. lacZ expression is induced in a detectable number of cocultured T cells, even when the ovalbumin cDNA consists of only 1:10(4) of the total DNA used to transfect the COS cells. These results suggest that unknown T-cell antigens may be identified by screening cDNA libraries in MHC-expressing COS cells using lacZ-inducible T cells as indicators of peptide antigen expression.

Animals↗
PubMed1992

Identification and characterization of the effector region within human C5a responsible for stimulation of IL-6 synthesis.

Human C fragment C5a is known to be a proinflammatory mediator and more recently shown to be a potent modulator of both humoral and cell-mediated immunity. We recently reported that natural and recombinant C5a induces the synthesis of IL-6-specific mRNA and secreted protein from human monocytes. Our studies using analogue peptides that are homologous to the carboxyl-terminal sequence of human C5a, indicate that the "effector" site for inducing IL-6 synthesis resides within the C-terminal region (C5a (70-74)) of the C5a molecule. C5a peptides containing the exact sequence of the natural factor were found to retain full agonist activity but exhibited low potency (0.01-0.1% of intact C5a). It was also shown that amino acid substitutions in the C5a peptides by aromatic/hydrophobic residues, outside the immediate effector site, resulted in analogue peptides with a substantial increase in potency relative to the most active natural peptide (C5a (56-74)). Moreover, these peptides approach the potency of natural C5a for induction of IL-6. Taken together, these results suggest that the inflammatory and immunoregulatory activities associated with C5a may, in part, be due to the synthesis of IL-6.

Amino Acid Sequence↗
PubMed1991

Mesenteric venous thrombosis due to protein C deficiency.

Protein C deficiency is a known underlying risk factor for thromboembolic disease. Most commonly it presents as thrombophlebitis, deep venous thrombosis or pulmonary embolism. Less common presentations are becoming increasingly recognized now that assays for protein C are more widely available. We present two cases of mesenteric venous thrombosis who were found to have protein C deficiency.

Adult↗
PubMed1990

Requirement for solutions with oncotic pressure to release ANF during blood volume expansion in conscious and anesthetized rats.

We examined the effect of a 30% blood volume expansion with either blood, isotonic saline, or isotonic saline plus albumin on the release of immunoreactive-atrial natriuretic factor (IR-ANF) in conscious and barbiturate-anesthetized rats. Immediately prior to volume expansion, resting plasma IR-ANF levels were significantly (p less than 0.05) higher in the conscious animals (61 +/- 5 pg/mL, n = 19) compared to the anesthetized animals (41 +/- 3 pg/mL, n = 19). Volume expansion with blood from donor rats significantly (p less than 0.05) elevated IR-ANF in both groups, but the increase in the conscious rats (+492 +/- 32 pg/mL, n = 6) was significantly (p less than 0.05) greater than that of the anesthetized rats (74 +/- 25 pg/mL, n = 6). Similarly, volume expansion with isotonic saline containing 38 mg/mL albumin significantly (p less than 0.05) elevated IR-ANF levels in both groups, but the increase in the conscious group (379 +/- 102 pg/mL, n = 7) was significantly (p less than 0.05) greater than that of the anesthetized group (94 +/- 32 pg/mL, n = 7). These elevations in IR-ANF levels were not significantly different between either of the conscious groups or either of the anesthetized groups. Volume expansion with isotonic saline alone did not have any significant effect upon resting IR-ANF levels in either conscious (+8 +/- 14 pg/mL, n = 6) or anesthetized (-7 +/- 6 pg/mL, n = 6) animals. From these results, it would appear that a) isotonic saline alone does not stimulate IR-ANF release when used to expand blood volume, and b) barbiturate anesthesia significantly lowers resting plasma IR-ANF levels and attenuates the release of IR-ANF in response to volume expansion.

Albumins↗