Amyloid L, abbreviated as "AL" (AL=amyloid light), belongs to a group of polymorphic fibre proteins which, in acquired amyloidosis, are deposited as insoluble, fibrillar aggregates in organs, vessels and nerves. Amyloidosis is caused by a disturbance in protein folding.
Amyloid of the immunoglobulin light chain type (AL=amyloid light). Precursor proteins are monoclonal immunoglobulin light chains. According to the iso and idiotypes, AL proteins are chemically diverse. Two skin types are distinguished: Aκ and Aλ.
AL amyloid is present in a number of very different forms of amyloidosis, such as monoclonal gammopathy and malignant monoclonal B-cell proliferation (multiple myeloma, Bence-Jones plasmacytoma, Waldenström's disease, etc.).