Expression of an immunoglobulin VH gene in natural anti-hapten antibodies

Nonimmune sera of CBA and C57BL/6 mice had similar anti-(4-hydroxy-3-nitrophenyl)acetyl (NP) titers, but the fine specificities (relative affinities for cross-reactive haptens (4-hydroxy-5-iodo-3-nitrophenyl)acetyl (NIP) and (4-hydroxy-3,5-dinitrophenyl)acetyl (NNP)) were very different. Natural anti-NP antibodies of the C57BL/6 mice resembled immune anti-NP antibodies in being heteroclitic without exception, while both normal and immune anti-NP of the CBA mice were nonheteroclitic. Breeding studies suggested that the C57BL/6 trait of the natural antibodies was controlled by the same VH gene as the C57BL/6 trait of immune anti-NP antibodies.