Distribution of an Arginine–Lysine Interchange in the Invariable Half of Human L-Type Bence-Jones Proteins

SEROLOGICAL reagents have been used to identify allelic antigenic determinants of the peptide chains of immunoglobulins 1 . Several allotypic determinants of the heavy chains of human immunoglobulins have been identified 2 and their distribution in human populations 3 has been investigated. Only a few allotypic determinants of the K-type light chain of human immunoglobulins have been identified 2 and one of these has been correlated with an amino-acid interchange in the invariable half of these peptide chains 4–6 . No homologous serological reagent has been available for the study of the L-type light chain.