CD30 activation induces apoptotic death of ALCL cells but not of HD cells.

(A) The ALCL cell lines Karpas 299 and Michel and the HD cell lines KM-H2, L428, and L591 were stained for CD30 and examined by flow cytometry for CD30 expression. The Raji cell line was used as a negative control. The thinner lines indicate the FITC-isotype control antibody and the bold lines indicate a FITC-conjugated anti-CD30 antibody. (B) The ALCL cell lines Karpas and Michel and the HD cell lines KM-H2, L428, and L591 were incubated for 24 hours with the immobilized CD30 agonistic antibody M67 (▪) or isotype control antibodies (■) and measured for viability by PI exclusion after 24 hours. (C) The ALCL cell lines Karpas and Michel and the HD cell lines KM-H2 and L428 were preincubated with either a media control (□) or with the protein synthesis inhibitor cycloheximide (10 μg/mL) (■) and then incubated for 24 hours with the immobilized CD30 agonistic antibody before viability was measured. For each cell line, the viability of cells incubated with control IgG antibody was defined as zero. The viabilities of cells treated with cycloheximide plus IgG was indistinguishable from IgG alone. (D) Michel cells were incubated with immobilized CD30 agonistic antibody (♦) or isotype control antibody (■) for the indicated periods of time prior to viability analysis. (E) Karpas and Michel cells were preincubated with cycloheximide (2 μg/mL) in addition to the general caspase inhibitor ZVAD-fmk (▪, 50 μmol/L in dimethyl sulfoxide; Enzyme Systems Products, Livermore, CA) or a mock control followed by incubation with the immobilized CD30 agonistic antibodies M67 (▧) or isotype control antibodies (■). Viability was measured by PI exclusion 24 hours later.