A new allotype in the rabbit linked with As1 which may characterize a new class of IgG

Some antiallotype sera are found to be specific for allotypic determinants on two genetically closely linked categories of IgG globulins in the rabbit. Genetic and immunological evidence presented indicate that these two categories are two different IgG classes differing by their A chains. These have been called IgG1, defined by allotypic specificity As1 or its alleles, and IgG2, defined by allotypic specificity As8 or its alleles. Anti-DNP antibodies were shown to be present in both classes. A comparison with known allotypes in man, mouse and rabbit suggest that the structural genes for the A chains of the immuno-globulins are clustered together in a small chromosome region.