Immunodominant minor histocompatibility antigen peptides presented by H2D^b molecules

Background. C57BL/6 (B6) mice generate cytolytic T lymphocytes (CTLs) to a limited number of immunodominant cytotoxic T cell target (CTT) antigens and associated peptides when primed with H2-matched BALB.B spleen cells, despite multiple minor histocompatibility antigen (HA) differences. We previously showed that these CTLS recognize four K^b-bound minor HA peptides derived from CTT antigens. Here, we describe the identification of D^b-bound minor HA peptides recognized by B6 anti-BALB.B CTLs. Methods. Peptides were extracted from D^b molecules immunoprecipitated from lysates of T lymphoblasts from BALB.B mice and mice from the CXB recombinant inbred strains that express H2^b and segregate minor HA from BALB/c and B6. Peptides were separated by reverse-phase high-performance liquid chromatography and tested for sensitization of targets for lysis by CTLs specific for BALB.B and the CXB strains. Results. B6 anti-BALB.B CTLs recognized a single D^b-bound peptide whose distribution in CXB strains matched that of the previously reported CTT-1 minor HA. An additional D^b-bound peptide (CTT-7) was recognized by B6 anti-CXBG CTLs. CTT-1 was expressed by independently derived inbred mouse strains that express H2^b. CTT-1 was recognized by B6 CTLS specific for these inbred strains, except for the LP and 129 strains that stimulated CTL specific for the CTT-8 peptide expressed by these two strains. Conclusions. These results demonstrate that B6 CTLs primed and boosted with multiple minor HA recognize a maximum of two minor HA peptides regardless of the strain of origin of H2^b-matched stimulating lymphoid cells.