Identification of mimotopes for the H4 minor histocompatibility antigen.
The H4 minor histocompatibility antigen (HA) of mice includes a single immunogenic peptide presented by H-2Kb molecules that stimulates skin allograft rejection and is immunodominant in the stimulation of cytolytic T lymphocytes (CTL) specific for multiple minor HA. We have identified H4 mimotopes that are recognized by the H4-specific M9 CTL clone through the use of a random peptide library comprised of bacterial clones expressing an inducible fusion protein tailed with the octamer sequence SXIXFXXL. Eight discrete mimotopes were identified that sensitized RMA-S cells for lysis by M9 CTL down to concentrations of 10(-11) M. Comparable reactivity was observed with a short-term, H4-specific CTL line indicating that the mimotopes were not solely specific for the selecting M9 clone. All mimotopes included Gly at p2 and either Val or Ile at p4, suggesting a requirement for a hydrophobic residue with specific conformation. All mimotopes included either Arg or His at p7, implicating a requirement for a specific positively charged amino acid at that position. The sixth position was more variable with four of eight mimotopes having a Val residue with single mimotopes including alternative amino acids, the majority of which were hydrophobic. Analysis of mimotopes for hydrophobicity and charge by reverse-phase HPLC and capillary electrophoresis respectively indicated that (i) mimotopes with Val at both p4 and p6 were hydrophobically similar (but not identical) to the natural H4 peptide, and (ii) a S --> E substitution at p1 resulted in a peptide (EGIVFVRL) with charge characteristics equivalent to those of the natural H4 peptide.
Strausbauch
M A
MA
Department of Surgery, Mayo Foundation, Rochester, MN 55905, USA.
Nevala
W K
WK
Roopenian
D C
DC
Stefanski
H E
HE
Wettstein
P J
PJ
D000595:Amino Acid Sequence; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D019075:Electrophoresis, Capillary / Q000379:methods; D000939:Epitopes / Q000032:analysis / Q000276:immunology / Q000302:isolation & purification; D006183:H-2 Antigens / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D015778:Minor Histocompatibility Antigens / Q000276:immunology*; D008969:Molecular Sequence Data; D010455:Peptides / Q000276:immunology* / Q000302:isolation & purification; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology
D000939:Epitopes; D006183:H-2 Antigens; D015778:Minor Histocompatibility Antigens; D010455:Peptides