FRAGMENTS OF THE CONSTANT-REGION OF IMMUNOGLOBULIN LIGHT-CHAINS ARE CONSTITUENTS OF AL-AMYLOID PROTEINS

Immunoglobulin light chains are the precursor proteins of AL-amyloidos is. In the fibril formation process properties of the variable part of the immunoglobulin light chains are believed to be of major importanc e. In this work it is shown that fragments of the constant part of the immunoglobulin light chain are a constituent of the AL-amyloid protei ns of kappa type. A specific antiserum has identified these fragments in gel filtration fractions where the absorbance approached the base l ine after the main retarded peak. The fragments are small and have bee n overlooked previously in the purification process. The significance of the constant part in AL-proteins is unclear, but adds new aspects t o the discussion of pre- or post-fibrillogenic cleavage of the immunog lobulin light chains. (C) 1998 Academic Press.