ABSTRACT
We have analyzed a panel of T cell hybridomas specific for the chemically dominant epitope of hen egg-white lysozyme 48-61 which has asparagine 59 as an important T cell receptor contact residue. A number of T cells recognize 48-61 with asparagine at position 59, but not the aspartic acid or isoaspartic acid derivatives. Conversely, we find T cells that specifically recognize 48-61 bearing an isoaspartic acid at residue 59, but not asparagine. For other T cells, asparagine, aspartic acid, or isoaspartic acid at residue 59 is irrelevant. We present evidence that our previous distinction between type A and type B T cells is not explained by asparagine deamidation at residue 59.
Subject(s)
Asparagine/immunology , Epitopes, T-Lymphocyte/immunology , Major Histocompatibility Complex/immunology , Muramidase/immunology , Peptide Fragments/immunology , T-Lymphocytes/immunology , Animals , Antigen Presentation/immunology , Aspartic Acid/immunology , Isoaspartic Acid/immunology , Mice , Peptides/immunology , Tumor Cells, CulturedABSTRACT
We examined the antigenic specificity of two T cell hybridomas elicited against the disaccharide galabiose attached to the fifth residue of the I-Ak binding peptide 52-61 of lysozyme. By making changes in the saccharide molecule and in the peptide, we conclude that the outer galactose residue of the galabiose moiety is directly recognized by the T cells together with the exposed side chains of the peptide. The overall spatial display of this galactose moiety on the 52-61 peptide is likewise important.
Subject(s)
Amino Acids/immunology , CD4-Positive T-Lymphocytes/metabolism , Disaccharides/immunology , Epitopes, T-Lymphocyte/metabolism , Glycopeptides/immunology , Glycopeptides/metabolism , Histocompatibility Antigens Class II/metabolism , Amino Acids/metabolism , Animals , Binding Sites/immunology , CD4-Positive T-Lymphocytes/immunology , Disaccharides/metabolism , Glycine/immunology , Glycine/metabolism , Glycopeptides/chemistry , Hybridomas , Mice , Mice, Inbred CBA , Muramidase/immunology , Muramidase/metabolism , Peptide Fragments/immunology , Peptide Fragments/metabolism , Receptors, Antigen, T-Cell/metabolism , Serine/immunology , Serine/metabolismABSTRACT
Mice lacking the gp91 protein of reduced nicotinamide adenine dinucleotide phosphate oxidase showed heightened susceptibility to Listeria infection. The enhanced susceptibility was noted 2 days after infection, the usual peak time of the neutrophil-dependent lesion in the liver. Infected gp91phox -/- mice had an increase of approximately 30-fold in Listeria in the liver and an increase in the number of microabscesses. The study of the gp91phox mice underscores the early role of the neutrophil and of an oxidative burst in this infection with an intracellular pathogen. These results contrast with others showing that the late macrophage-dependent stage of the infection is dependent on nitric oxide.
Subject(s)
Listeriosis/immunology , NADPH Oxidases/deficiency , Animals , Disease Susceptibility , Liver/microbiology , Mice , Respiratory BurstABSTRACT
Here we describe generation of Aw3.18, a monoclonal antibody that recognizes peptide residues 48-62 of hen egg lysozyme (HEL) bound to the MHC class II molecule I-Ak. Epitope mapping revealed that Aw3.18 detects a change in the solvent-exposed surface of this peptide-MHC complex upon substitution of the peptide side chain at position P1. Furthermore, Aw3.18 blocked recognition by some, but not all, of the HEL 48-62-reactive T cell hybridomas tested, suggesting a heterogeneity in the T cell response toward this complex. Finally, using Aw3.18, it was possible to determine the fraction of I-Ak molecules loaded with 48-62 peptide after culture of an antigen-presenting cell in medium containing HEL.
