Serum Immunoglobulin Free Light Chain Assessment in IgG4-Related Disease

Immunoglobulin free light chains are produced in excess during normal antibody synthesis. Their evaluation is commonly used in case of a monoclonal gammopathy. In polyclonal hypergammaglobulinemia related to the Sjögren syndrome or systemic lupus, erythematosus serum free light chain levels are increased and could correlate with disease activity. We show here that the κ () and λ () free light chains and the κ : λ ratio () are increased in...