Interleukin-4 inhibits apoptotic cell death and loss of the bcl-2 protein in B-chronic lymphocytic leukaemia cells in vitro.
When monoclonal B cells from B-chronic lymphocytic leukaemia (B-CLL) patients are cultured in vitro, they die by apoptosis. Apoptotic cell death occurred in the B cells from 20/24 B-CLL patients after 26-30 h in in vitro culture, with 14.3-59.0% (mean 33.6%) of their DNA being fragmented in approximately 180 base pair multimers. After 8-10 d culture, 90-100% of the B-CLL cells were dead. Cell death and DNA fragmentation were inhibited in the presence of 0.5-5 ng/ml human recombinant interleukin-4 (IL-4) and viable monoclonal B cells could be maintained in culture up to 3 weeks. At 5 ng/ml, IL-4 reduced  DNA fragmentation after a 26-30 h culture to 2.2-33.3% (mean 14.9%). IL-4 inhibited apoptosis without stimulating cell proliferation. In four patients the cells were resistant to apoptosis in vitro and they could be maintained for up to 4 weeks in culture medium alone. DNA fragmentation in all patients was increased in the presence of the RNA synthesis inhibitor actinomycin-D. Western blot analysis of cell lysates showed expression of the bcl-2 protein in all 11 B-CLL patients studied. However, during culture, bcl-2 protein levels were preserved only in patients resistant to apoptosis and were reduced in those susceptible to apoptosis. Reduction of bcl-2 protein levels was inhibited in cells cultured in the presence of IL-4. These data offer an explanation for the difference between the long life in vivo and rapid death in vitro of B-CLL cells and indicate that IL-4 may participate in the extended survival of these non-dividing cells in vivo.
Panayiotidis
P
P
Department of Haematology, Royal Free Hospital, School of Medicine, London.
Ganeshaguru
K
K
Jabbar
S A
SA
Hoffbrand
A V
AV
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D002470:Cell Survival / Q000187:drug effects; D004273:DNA, Neoplasm / Q000187:drug effects; D005260:Female; D006801:Humans; D015847:Interleukin-4 / Q000494:pharmacology*; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000032:analysis; D011518:Proto-Oncogene Proteins / Q000032:analysis / Q000187:drug effects*; D019253:Proto-Oncogene Proteins c-bcl-2; D011994:Recombinant Proteins / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D004273:DNA, Neoplasm; D009363:Neoplasm Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D011994:Recombinant Proteins; D015847:Interleukin-4