title: Analysis of lysozyme-specific immune responses by synthetic peptides. I. Characterization of antibody and T cell-mediated responses to the N-terminal peptide of hen egg-white lysozyme.
abstract: The immunological reactivity against the N-terminal region of hen egg-white lysozyme (HEL) has been investigated by a synthetic peptide (PHEL) comprising residue 1-18 of HEL and by an analogue peptide (PREL) in which phenylalanine at position 3 is substituted by tyrosine. Both peptides are immunogenic in (C57BL/10 X DBA/2)F1 mice genetically responder to HEL. In C57BL/6 mice, genetically nonresponder to HEL, PREL induces anti-peptide antibodies that also bind to PHEL whereas PHEL is not immunogenic. Thus, a single amino acid substitution in a synthetic peptide converts a nonresponder mouse strain into a responder one. Anti-PHEL antibodies demonstrate a higher binding to HEL than anti-PREL antibodies, indicating that phenylalanine at position 3 is important for induction of anti-peptide antibodies able to recognize native HEL. At the T cell level the two peptides show very high bidirectional cross-reactivity between themselves and with HEL for interleukin 2 production, antigen-specific proliferation and delayed-type hypersensitivity response, whereas conservation of phenylalanine at position 3 is required for induction of suppressor cells cross-reactive with HEL. This indicates that the N-terminal region of HEL contains epitope(s) able to induce the same level of helper T cell activity as the native HEL molecule. However, helper T cells do not discriminate between PHEL and PREL whereas phenylalanine at position 3 is critical for HEL-specific suppressor T cell induction.
mesh_terms: D000818:Animals; D000917:Antibody Formation; D000937:Antigen-Antibody Reactions; D001402:B-Lymphocytes / Q000276:immunology; D005260:Female; D006968:Hypersensitivity, Delayed / Q000276:immunology; D007108:Immune Tolerance; D007111:Immunity, Cellular; D007376:Interleukin-2 / Q000096:biosynthesis; D008213:Lymphocyte Activation; D051379:Mice; D009113:Muramidase / Q000276:immunology*; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology
chemical_list: D007376:Interleukin-2; D010446:Peptide Fragments; D009113:Muramidase