[Apoptosis in chronic lymphocytic leukemia].
Chronic lymphocytic leukemia of B cells (B-CLL) is the most prevalent leukemia in the Occidental Hemisphere. It is characterized by a progressive accumulation of monoclonal CD5+ B lymphocytes, with low amounts of surface Ig. Most B-CLL cells are arrested in the G0 phase of the cell cycle; therefore their accumulation in vivo appears to result from the inhibition of apoptosis which has been attributed to over-expression of the anti-apoptotic protein Bcl-2. When cultured in vitro, spontaneous apoptosis occurs, suggesting the existence in vivo of survival-promoting factors. We here show that non-malignant leukocytes, particularly monocytes and NK cells, are able to inhibit B-CLL cells apoptosis, at least in part, through the release of soluble factors. Neutralizing antibodies directed to interferon-gamma or IL-4 only partially abolish the protecting effects of accessory cells suggesting that they are not the main cytokines involved. Increased apoptosis of B-CLL cells is not associated with modifications in the expression of Bcl-2, Fas or Fas ligand. Considering that B-CLL is associated to autoimmune phenomena and recurrent infections due to hypogammaglobulinemia, it should be interesting to correlate the activation of immune responses with disease progression.
Giordano
M
M
Instituto de Investigaciones Hematológicas, Academia Nacional de Medicina, P. Melo 3081, 1425 Buenos Aires, Argentina. mirtagiordano@imaginaria.com.ar
D000938:Antigen-Presenting Cells / Q000276:immunology / Q000378:metabolism; D017209:Apoptosis; D006801:Humans; D007694:Killer Cells, Natural / Q000502:physiology; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000276:immunology / Q000473:pathology*; D007962:Leukocytes / Q000502:physiology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000276:immunology / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D019253:Proto-Oncogene Proteins c-bcl-2