Twenty-eight cases of chylous ascites occurring over the past 20 years are analyzed for clinical presentation, cause, yield of diagnostic procedure used, and response to therapy. Malignancies were responsible for 21 of 24 adult cases of chyloperitoneum, with lymphomas predominating (13 cases). The dismal prognosis in adult cases (12 patients died within 3 months) shows the need for appropriate diagnostic assessment including early lymph node biopsy or laparotomy, or both, when indicated. Surgery, chemotherapy, or radiation therapy should be instituted promptly except in cases resulting from surgical trauma to lymphatics, which frequently resolve with conservative management. Three of the four pediatric cases of chylous ascites resulted from congenital lymphatic anomalies; the fourth case resulted from operative trauma. Aggressive diagnostic and therapeutic interventions are not warranted in childhood cases of chylous ascites until conservative management (paracentesis, low-fat diet, medium-chain triglyceride supplementation) has failed; neoplasia is rarely implicated and many cases resolve within a few months.

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CD20 is a nonglycosylated 33 to 37 kD phosphoprotein involved in B-cell signaling that subserves important functions in the regulation of B-cell proliferation and differentiation. In addition, this B-cell surface antigen has been shown recently to be an effective target for immunotherapy of B-cell malignancies using chimeric (mouse/human) or radiolabeled murine monoclonal anti-CD20 antibodies. In this report we show that extensive crosslinking of CD20 with murine anti-CD20 monoclonal antibodies (MoAbs) in the presence of either goat anti-mouse IgG or Fc receptor (FcR)-expressing cells directly inhibits B-cell proliferation, induces nuclear DNA fragmentation, and leads to cell death by apoptosis. The apoptotic effects of these MoAbs can be inhibited by chelation of extracellular or intracellular Ca 2؉ by EGTA orBapta AM, indicating that anti-CD20-mediated apoptosis may be related to changes in Ca 2؉ concentration. These findings suggest that ligation of CD20 in vivo by anti-CD20 antibodies in the presence of FcR-expressing cells may initiate signal transduction events that induce elevation of [Ca 2؉ ] i and lead to apoptosis of malignant B cells, thereby contributing to the impressive tumor regressions observed in mouse models and clinical trials using anti-CD20 MoAbs.