Takahashi I, Matsushita K, Nisizawa T, Okahashi N, Russell M W, Suzuki Y, Munekata E, Koga T
Department of Dental Research, National Institute of Health, Tokyo, Japan.
Infect Immun. 1992 Feb;60(2):623-9. doi: 10.1128/iai.60.2.623-629.1992.
The immune responses to a cell surface protein antigen (PAc) of Streptococcus mutans and a peptide corresponding to residues 301 to 319 of the protein antigen [PAc(301-319)] in various strains of mice were studied, with attention being given to the haplotype of major histocompatibility complex (MHC) class II genes. Subcutaneous immunization of mice carrying the MHC class II I-Ad gene [BALB/c, B10.D2, B10.GD, and (B10.D2 x B10.G)F1 mice] with the peptide induced strong serum immunoglobulin G (IgG) responses to recombinant PAc (rPAc) and the peptide. Subcutaneous immunization of mice carrying the haplotype k or b of the H-2 I-A gene (C3H/HeN, C57BL/6, B10.BR, B10.A, or B10 mice) with the peptide induced intermediate serum IgG responses to rPAc and the peptide, and subcutaneous immunization of mice carrying the haplotype s or q of the H-2 I-A gene (DBA/1, B10.S, or B10.G mice) induced weak serum IgG responses to rPAc and the peptide compared with the responses of mice carrying the I-Ad gene. PAc(301-319) strongly induced PAc(301-319)-specific T-cell proliferation in B10.D2 mice but not in B10.G mice. The T-cell proliferation in B10.D2 mice was inhibited by treatment of antigen-presenting cells with anti-I-Ad monoclonal antibody but not with anti-I-Ab monoclonal antibody. These results indicate that the immune responses to the peptide in mice are genetically restricted or dominated by the MHC class II gene (I-Ad). To map antigenic epitopes in PAc(301-319) and PAc in mice bearing different H-2 haplotypes, 10 overlapping decapeptides covering PAc(301-319) and 153 decapeptides covering the entire mature PAc were synthesized. Of 10 decapeptides covering PAc(301-319), 6, 7, 1, and 1 decapeptides showed strong reactions with anti-PAc(301-319) sera from B10.D2 (H-2d), B10.GD (H-2g2), B10.BR (H-2k), and B10.A (H-2a) mice, respectively. None of these overlapping decapeptides reacted with anti-PAc(301-319) sera from B10.S (H-2s) and B10.G (H-2q) mice. Epitope-scanning analyses of the mature PAc molecule showed that antigenic epitopes scattered throughout the molecule and that antigenic epitope patterns differed in mice with different H-2 haplotypes. In addition, there was little overlap of immunogenic peptides among the mice with different haplotypes.
研究了不同品系小鼠对变形链球菌细胞表面蛋白抗原（PAc）以及与该蛋白抗原第301至319位残基对应的肽段[PAc(301 - 319)]的免疫反应，并着重关注主要组织相容性复合体（MHC）II类基因的单倍型。用该肽段对携带MHC II类I - Ad基因的小鼠[BALB/c、B10.D2、B10.GD和（B10.D2×B10.G）F1小鼠]进行皮下免疫，可诱导其对重组PAc（rPAc）和该肽段产生强烈的血清免疫球蛋白G（IgG）反应。用该肽段对携带H - 2 I - A基因单倍型k或b的小鼠（C3H/HeN、C57BL/6、B10.BR、B10.A或B10小鼠）进行皮下免疫，可诱导其对rPAc和该肽段产生中等强度的血清IgG反应，而用该肽段对携带H - 2 I - A基因单倍型s或q的小鼠（DBA/1、B10.S或B10.G小鼠）进行皮下免疫，与携带I - Ad基因的小鼠相比，诱导产生的对rPAc和该肽段的血清IgG反应较弱。PAc(301 - 319)能强烈诱导B10.D2小鼠中PAc(301 - 319)特异性T细胞增殖，但不能诱导B10.G小鼠中的T细胞增殖。用抗I - Ad单克隆抗体处理抗原呈递细胞可抑制B10.D2小鼠中的T细胞增殖，但用抗I - Ab单克隆抗体处理则无此作用。这些结果表明，小鼠对该肽段的免疫反应受到遗传限制或由MHC II类基因（I - Ad）主导。为了在携带不同H - 2单倍型的小鼠中定位PAc(301 - 319)和PAc中的抗原表位，合成了覆盖PAc(301 - 319)的10个重叠十肽以及覆盖整个成熟PAc的153个十肽。在覆盖PAc(301 - 319)的10个十肽中，分别有6个、7个、1个和1个十肽与来自B10.D2（H - 2d）、B10.GD（H - 2g2）、B10.BR（H - 2k）和B10.A（H - 2a）小鼠的抗PAc(301 - 319)血清发生强烈反应。这些重叠十肽均未与来自B10.S（H - 2s）和B10.G（H - 2q）小鼠的抗PAc(301 - 319)血清发生反应。对成熟PAc分子的表位扫描分析表明，抗原表位分散在整个分子中，且在具有不同H - 2单倍型的小鼠中抗原表位模式不同。此外，不同单倍型小鼠之间免疫原性肽的重叠很少。
