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CD52 over-expression affects rituximab-associated complement-mediated cytotoxicity but not antibody-dependent cellular cytotoxicity: Preclinical evidence that targeting CD52 with alemtuzumab may reverse acquired resistance to rituximab in non-Hodgkin lymphoma

2007; Taylor & Francis; Volume: 48; Issue: 12 Linguagem: Inglês

10.1080/10428190701647879

1042-8194

Raymond Cruz, Francisco J. Hernandez‐Ilizaliturri, Scott H. Olejniczak, George Deeb, Joy Knight, Paul K. Wallace, Beth L. Thurberg, William Kennedy, Myron S. Czuczman,

Chronic Lymphocytic Leukemia Research

In an attempt to define mechanisms by which B-cell non-Hodgkin lymphoma (NHL) may escape rituximab immunotherapy, we developed several rituximab-resistant cell lines (RRCL) generated from the rituximab-sensitive cell lines (RSCL) Raji and RL. Rituximab resistance was associated with CD20 downregulation and upregulation of CD52 and the complement inhibitory proteins (CIPs) CD55 and CD59. No significant alemtuzumab-associated complement-mediated cell lysis (CMC) or antibody-dependent cellular cytotoxicity (ADCC) was demonstrated in RSCL. In contrast, in vitro exposure of RRCL to alemtuzumab resulted in a significant degree of CMC and ADCC. Of note, in vitro blocking of CD52 with anti-CD52 F(ab')(2) fractions in RRCL improved rituximab-associated CMC as compared to unblocked RRCL. Our current data provides a basis for further evaluation of alemtuzumab-based clinical trials for patients with rituximab-resistant NHL.