Fulton R J, Davie J M
J Immunol. 1984 Jul;133(1):465-70.
The VK1GAC light chain represents the dominant V kappa structure employed in the antibody response of A/J mice to streptococcal group A carbohydrate ( GAC ). Two anti-idiotypic antisera, anti- Id5 and anti- Id20 , with specificity for the VK1GAC light chain were used to examine anti- GAC antibody responses in a series of inbred mouse strains that differ at the heavy chain constant region ( IgCH ) allotype locus. Both idiotypes were expressed in normal and immune sera from mice of most IgCH allotypes, except IgCHb (C57BL/6J) and IgCHf (CE/J). C57BL/6J mice expressed Id5 , but not Id20 , whereas CE/J mice did not express either idiotype. Testing of recombinant inbred strains between BALB/c and C57BL/6 indicated that the pattern of idiotype expression did not correlate with IgCH allotype. The C X B recombinants expressed all three idiotype patterns that were observed in the panel of inbred strains. Testing of allotype congenic mice between BALB/c and C57BL/6 showed that CB.20 and BC.8 mice were Id20 -, whereas BAB-14 mice were Id20 +, indicating that both VH and background (V kappa or regulatory) loci must be derived from BALB/c to obtain Id20 expression. The difference in the frequency of idiotype expression observed between BALB/c and BAB-14 mice indicates that the IgCH locus may exert a quantitative influence on the expression of this light chain. To examine the Id20 -, Id5 + antibodies of C57BL/6 mice, anti- GAC hybridomas were prepared. Of 16 C57BL/6-derived anti- GAC monoclonal antibodies, six were reactive with anti- Id5 and not with anti- Id20 . Isoelectric focusing of the purified kappa light chains from three of these antibodies revealed two distinct spectrotypes that co-migrated with the two known VK1GAC spectrotypes observed with A/J anti- GAC light chains. Idiotypic analysis of in vitro recombinants between the heavy and light chains of A/J and C57BL/6 monoclonal antibodies demonstrated that the C57BL/6 light chains were idiotypically similar to A/J light chains when they were free in solution or paired with A/J heavy chains. These results demonstrate that C57BL/6 mice can express a light chain that is very similar, if not identical, to the VK1GAC light chain, although the light chain is expressed in lower frequency and is paired with a distinct VH structure, which can mask expression of one of the VK1GAC idiotypes. These effects on V kappa expression map to at least three genetic loci: VH, CH, and an unlinked locus.
VK1GAC轻链代表A/J小鼠对A组链球菌碳水化合物（GAC）抗体反应中所采用的主要Vκ结构。使用两种对VK1GAC轻链具有特异性的抗独特型抗血清，即抗Id5和抗Id20，来检测一系列在重链恒定区（IgCH）同种异型位点存在差异的近交系小鼠品系中的抗GAC抗体反应。除了IgCHb（C57BL/6J）和IgCHf（CE/J）之外，大多数IgCH同种异型小鼠的正常血清和免疫血清中均表达这两种独特型。C57BL/6J小鼠表达Id5，但不表达Id20，而CE/J小鼠两种独特型均不表达。对BALB/c和C57BL/6之间的重组近交系进行检测表明，独特型表达模式与IgCH同种异型不相关。C×B重组体表达了在近交系小鼠组中观察到的所有三种独特型模式。对BALB/c和C57BL/6之间的同种异型同源近交系小鼠进行检测表明，CB.20和BC.8小鼠为Id20阴性，而BAB-14小鼠为Id20阳性，这表明VH和背景（Vκ或调节）位点都必须来自BALB/c才能获得Id20表达。在BALB/c和BAB-14小鼠之间观察到的独特型表达频率差异表明，IgCH位点可能对这种轻链的表达产生定量影响。为了检测C57BL/6小鼠的Id20阴性、Id5阳性抗体，制备了抗GAC杂交瘤。在16种源自C57BL/6的抗GAC单克隆抗体中，有6种与抗Id5反应，但不与抗Id20反应。对其中三种抗体纯化的κ轻链进行等电聚焦分析，发现了两种不同的光谱型，它们与用A/J抗GAC轻链观察到的两种已知VK1GAC光谱型共迁移。对A/J和C57BL/6单克隆抗体的重链和轻链之间的体外重组体进行独特型分析表明，当C57BL/6轻链在溶液中游离或与A/J重链配对时，其独特型与A/J轻链相似。这些结果表明，C57BL/6小鼠可以表达一种与VK1GAC轻链非常相似（如果不是完全相同）的轻链，尽管这种轻链表达频率较低，并且与一种独特的VH结构配对，这可能会掩盖VK1GAC独特型之一的表达。这些对Vκ表达的影响至少映射到三个基因位点：VH、CH和一个不连锁的位点。
