Zum Mechanismus der Antikörperbildung

Abstract

Antibody-specifity is determined by the primary sequence of the constituent L-and H-chains of immunoglobulins. Differences in sequence between different immunoglobulin-chains of the same antigenic grouping and genetic constitution are confined to certain sections of the molecule which in the L-chains is the N-terminal half. These differences closely resemble those caused by evolution, but cannot be caused directly by evolution because the C-terminal half of the molecule is controlled by the same gene. Variability must be produced by a somatic process whose mechanism is still not understood. According to the mechanism proposed here, the variability might be caused by interallelic somatic crossing-over between a limited number of serially repeated homologous genes. Simultaneously the gene is shortened to its definite length by controlled deletions. The serially repeated homologous genes could have been formed by several gene-duplications during evoluion. Variability is produced, not by repeating evolution in every single step, but by only a few recombination steps taking advantage of structural differences which already exist in the genome. The gene-section for the constant region does not appear to take part in the recombination process, since its homology to the variable gene-section is too low.