CD40LG and monoclonal gammopathy: Serum immunoglobulin levels were IgG 466 mg/dL, IgA 74 mg/dL, and IgM 2789 mg/dL, serum free light-chain levels were kappa-light chain 24.4 mg/L and lambda-light chain 15.8 mg/L (kappa-to-lambda serum free light-chain ratio of 1.54) and plasma electrophoresis revealed IgM-kappa monoclonal gammopathy.