Suppression of the delayed-type hypersensitivity response to hen egg white lysozyme (HEL) by HEL peptides in a genetically high-responder mouse strain: evidence for requirement of the loop structure for induction of suppressor T cells.
The delayed-type hypersensitivity (DTH) response of C3H/HeN mice to hen egg white lysozyme (HEL) can be blocked by a single iv injection of a solution of HEL in buffered saline 7 days before sensitization of animals with HEL in complete Freund's adjuvant (CFA). The minimal structure of HEL required for the suppression was examined by determining the abilities of various HEL-derivative peptides to inhibit HEL-DTH. Treatment of normal mice with Ploop I X II, sequence 57-107 (Cys64-Cys80, Cys76-Cys94), or P17 (sequences 1-27 and 123-129 linked by Cys6-Cys127) 7 days before immunization with HEL resulted in marked suppression of the DTH response. This inhibition of DTH involved generation of suppressor T cells (Ts). The results suggested that two suppressor pathways are involved. These data, together with another recent finding (1) that an entirely different portion of HEL is a suppressor determinant (SD) in A/J mice, indicate that different epitopes act as SDs in different strains of mice. Of the loop region peptides tested, Plc (intact loop I joined to a linear peptide, residues 84-97) was found to be the minimum structure capable of suppressing the HEL-DTH response; loop I or II alone did not cause suppression. Activation of Ts cells by the loop peptide depended on its conformational structure; completely reduced and carboxymethylated Ploop I X II did not cause suppression.
D000818:Animals; D000954:Antigens, Surface / Q000032:analysis; D000939:Epitopes; D005260:Female; D006968:Hypersensitivity, Delayed / Q000276:immunology*; D007108:Immune Tolerance; D007111:Immunity, Cellular; D051379:Mice; D008809:Mice, Inbred C3H; D009113:Muramidase / Q000276:immunology*; D010446:Peptide Fragments / Q000276:immunology; D011487:Protein Conformation; D013601:T-Lymphocytes / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*; D018800:Thy-1 Antigens
D000954:Antigens, Surface; D000939:Epitopes; D010446:Peptide Fragments; D018800:Thy-1 Antigens; D009113:Muramidase