calcimycin and Hodgkin-Disease

The activation marker CD30 is expressed on the cell surface of the malignant cells in Hodgkin's disease and a few non-Hodgkin lymphomas. We have analyzed the regulation of membrane-bound CD30 and found that the binding of a variety of anti-CD30 antibodies induced down-regulation of CD30 on cell lines. In addition, such down-modulation was also observed after treatment of the cell surface proteins with the sulfhydryl reagent iodoacetamide or after stimulation of the second messenger pathway with phorbol ester or calcium ionophore. This modulation was abolished at 4 degrees C and strongly inhibited by chelators like EDTA or 1,10-phenanthroline, whereas EGTA, a selective inhibitor of Ca(2+)-dependent proteinases and other inhibitors of serine, thiol and acid proteinases, showed no effect. The down-modulation was strengthened by Zn2+ or Cd2+, but not by other divalent cations such as Fe2+, Mn2+, Mg2+, Ca2+ or Co2+, thus indicating the involvement of a zinc metalloproteinase in CD30 modulation which can be activated by protein kinase C and by alkylation of sulfhydryl groups. Pulse-chase experiments, analysis of the CD30 glycosylation and specific measurement of the 90-kDa soluble form of CD30 (sCD30) with a sandwich radioimmunoassay revealed that CD30 down-modulation results from enhanced release of 90-kDa sCD30 by the site-specific cleavage of CD30 accomplished by a zinc metalloproteinase. This release occurs at the cell membrane without prior endocytosis.

Topics: Antibodies, Monoclonal; Calcimycin; Down-Regulation; Glycosylation; Hodgkin Disease; Humans; Iodoacetamide; Ionophores; Ki-1 Antigen; Kinetics; Lymphoma, Non-Hodgkin; Metalloendopeptidases; Solubility; Sulfhydryl Reagents; Tetradecanoylphorbol Acetate; Tumor Cells, Cultured

Absolute capacity for IL2 production by human peripheral blood mononuclear cells (PBMC) was studied using 12-O-tetradecanoylphorbol 13-acetate (TPA) and calcium ionophore A23187, which act synergistically, to induce lymphokine synthesis. Culture parameters were optimized for the TPA/A23187 stimulation such that maximal IL2 titers were produced with a high degree of reproducibility. Thus, using a synthetic medium, TPA/A23187 at 20/50ng/ml respectively, and a cell concentration of 2.5 X 10(6)/ml, IL2 titers in the cultures increased linearly over a period of 96h, reaching values at least 15-fold higher than with lectin stimulation. This allowed for determinations of IL2 synthetic capacity in individual blood samples. Large fluctuations in normal IL2 production (range 1775-10654 BRMP U/ml at 48h) were observed among 23 normal persons. A statistically significant lower IL2 productive capacity was observed in the age group above 40 as compared to those under 40. The lower rates of IL2 synthesis in a group of patients with Hodgkin's disease was seen only among those who had undergone immunosuppressive therapy; newly diagnosed cases fell within the normal range.

Topics: Calcimycin; Hodgkin Disease; Humans; In Vitro Techniques; Interleukin-2; Leukocytes; Lymphokines; Phytohemagglutinins; Reference Values; Tetradecanoylphorbol Acetate