To determine if, in vivo, mIgM-containing immunogenic PDm or μC4 are secreted or released from live cells by enzymatic means or by an apoptotic process, normal human serum, purified hu-IgM, and serum from Waldenstrom's Macroglobulinemia patients were each tested, bound to solid phase in ELISA assays, and found to be non-reactive with the mAb panel (p < 0.05) (Table 1D). Here, CD40LG is linked to macroglobulinemia.