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Dissecting the antigenic active components of BCG : role of bcg cell wall, inner membrane and cytoplasm

par Zlotta, Alexandre
Référence British journal of urology, 80, SUPPL. 2, page (34)
Publication Publié, 1997

Article révisé par les pairs

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Résumé :

Intravesical BCG is an effective treatment for superficial bladder cancer. However the nature of the active antigenic components of BCG is still poorly elucidated. Natural killer cells have been demonstrated to be involved in the mechanism of action of BCG. We have therefore analyzed the natural killer cell expansion by different subcomponents of BCG and their ability to enhance lymphocyte-mediated bladder tumor cell killing in an MHC-unrestricted manner in man. Human peripheral blood mononuclear cells (PMNC) were incubated with control medium, inner membrane of BCG, BCG cell wall, cytoplasmic extract of BCG, live BCG, and Interleukin-2 (15 u/ml, Il-2) for 7 days. Natural killer cells expansion was measured by facs analysis of CD3-, CD56+ lymphocytes. A chrome 51 release assay was used to assess the cytotoxicity of the amplified effectors cells against T24 human bladder cell line. All measurements and experiments were done at least in triplicate. On average, CD3-, CD56+ cells accounted for 5.2% of the lymphocyte population when PMNC were co-cultured with medium, and 8.1%, 9.0%, 9.8%, 8.1%, and 12.0% when PBMC were respectively co-cultured with cytoplasmic extract of BCG, whole BCG, BCG cell wall, BCG inner membrane, and IL-2 (all p<0.01). Against T24 cells, cytotoxicity of PMNC amplified with control medium, inner membrane, cell wall, cytoplasmic extract and live BCG reached on average 57%, 86%, 80%, 75% and 89% respectively. In vitro, our results suggest that several sub-components of BCG and in particular the cell wall and the inner membrane of BCG are as effective as BCG to expand natural killer cells and to enhance bladder tumor cell killing. Our data might help to further determine the active subcomponents of BCG. This might lead to use them in the future in animal models and in human trials in replacement of live BCG.