CD40LG and Waldenstrom macroglobulinemia: Side et al. reported a patient with Waldenström's macroglobulinemia and a calcium-binding IgM kappa, isolating and investigating the IgM paraprotein fraction in the patient's serum; the paraprotein fraction of the case patient contained calcium upon extraction, and gel mobility of the paraprotein was affected by calcium, whereas gel mobility of IgM paraproteins of three other patients was unaffected [9].