Mechanism of action of type II, glycoengineered, anti-CD20 monoclonal antibody GA101 in B-chronic lymphocytic leukemia whole blood assays in comparison with rituximab and alemtuzumab.
J Immunol
; 186(6): 3762-9, 2011 Mar 15.
Article
em En
| MEDLINE
| ID: mdl-21296976
ABSTRACT
We analyzed in B-chronic lymphocytic leukemia (B-CLL) whole blood assays the activity of therapeutic mAbs alemtuzumab, rituximab, and type II glycoengineered anti-CD20 mAb GA101. Whole blood samples were treated with Abs, and death of CD19(+) B-CLL was measured by flow cytometry. Alemtuzumab efficiently lysed B-CLL targets with maximal lysis at 1-4 h (62%). In contrast, rituximab induced a more limited cell death (21%) that was maximal only at 24 h. GA101 killed B-CLL targets to a similar extent but more rapidly than rituximab, with 19.2 and 23.5% cell death at 4 and 24 h, respectively, compared with 7.9 and 21.4% for rituximab. Lysis by both rituximab and GA101 correlated directly with CD20 expression levels (r(2) = 0.88 and 0.85, respectively). Interestingly, lysis by all three Abs at high concentrations was mostly complement dependent, because it was blocked by the anti-C5 Ab eculizumab by 90% in the case of alemtuzumab and rituximab and by 64% in the case of GA101. Although GA101 caused homotypic adhesion, it induced only limited (3%) direct cell death of purified B-CLL cells. Both rituximab and GA101 showed the same efficiency in phagocytosis assays, but phagocytosis was not significant in whole blood due to excess Igs. Finally, GA101 at 1-100 µg/ml induced 2- to 3-fold more efficient NK cell degranulation than rituximab in isolated B-CLL or normal PBMCs. GA101, but not rituximab, also mediated significant NK cell degranulation in whole blood samples. Thus, complement and Ab-dependent cellular cytotoxicity are believed to be the major effector mechanisms of GA101 in whole blood assays.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Leucemia Linfocítica Crônica de Células B
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Engenharia de Proteínas
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Antígenos CD20
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Anticorpos Monoclonais Murinos
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Anticorpos Monoclonais
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Anticorpos Antineoplásicos
Limite:
Humans
Idioma:
En
Revista:
J Immunol
Ano de publicação:
2011
Tipo de documento:
Article
País de afiliação:
Itália