title: Ex vivo-expanded cynomolgus macaque regulatory T cells are resistant to alemtuzumab-mediated cytotoxicity.
abstract: Alemtuzumab (Campath-1H) is a humanized monoclonal antibody (Ab) directed against CD52 that depletes lymphocytes and other leukocytes, mainly by complement-dependent mechanisms. We investigated the influence of alemtuzumab (i) on ex vivo-expanded cynomolgus monkey regulatory T cells (Treg) generated for prospective use in adoptive cell therapy and (ii) on naturally occurring Treg following alemtuzumab infusion. Treg were isolated from PBMC and lymph nodes and expanded for two rounds. CD52 expression, binding of alemtuzumab and both complement-mediated killing and Ab-dependent cell-mediated cytotoxicity (ADCC) were compared between freshly isolated and expanded Treg and effector T cells. Monkeys undergoing allogeneic heart transplantation given alemtuzumab were monitored for Treg and serum alemtuzumab activity. Ex vivo-expanded Treg showed progressive downregulation of CD52 expression, absence of alemtuzumab binding, minimal change in complement inhibitory protein (CD46) expression and no complement-dependent killing or ADCC. Infusion of alemtuzumab caused potent depletion of all lymphocytes, but a transient increase in the incidence of circulating Treg. After infusion of alemtuzumab, monkey serum killed fresh PBMC, but not expanded Treg. Thus, expanded cynomolgus monkey Treg are resistant to alemtuzumab-mediated, complement-dependent cytotoxicity. Furthermore, our data suggest that these expanded monkey Treg can be infused into graft recipients given alemtuzumab without risk of complement-mediated killing.
authors: Department of Surgery, Thomas E. Starzl Transplantation Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
authors: E M
authors: EM
authors: Dons
authors: G
authors: G
authors: Raimondi
authors: H
authors: H
authors: Zhang
authors: A F
authors: AF
authors: Zahorchak
authors: J K
authors: JK
authors: Bhama
authors: L
authors: L
authors: Lu
authors: M
authors: M
authors: Ezzelarab
authors: J N M
authors: JN
authors: Ijzermans
authors: D K C
authors: DK
authors: Cooper
authors: A W
authors: AW
authors: Thomson
mesh_terms: D000074323:Alemtuzumab; D000818:Animals; D061067:Antibodies, Monoclonal, Humanized / Q000097:blood / Q000494:pharmacology*; D000912:Antibodies, Neoplasm / Q000097:blood; D000920:Antibody-Dependent Cell Cytotoxicity; D015703:Antigens, CD / Q000378:metabolism*; D000951:Antigens, Neoplasm / Q000378:metabolism*; D000970:Antineoplastic Agents / Q000097:blood / Q000494:pharmacology*; D000074301:CD52 Antigen; D004912:Erythrocytes / Q000187:drug effects* / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism*; D007963:Leukocytes, Mononuclear / Q000187:drug effects* / Q000378:metabolism; D008252:Macaca fascicularis; D050378:T-Lymphocytes, Regulatory / Q000187:drug effects* / Q000378:metabolism
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D000912:Antibodies, Neoplasm; D015703:Antigens, CD; D000951:Antigens, Neoplasm; D000970:Antineoplastic Agents; D000074301:CD52 Antigen; D006023:Glycoproteins; D000074323:Alemtuzumab
keywords: Alemtuzumab; Campath-1H; nonhuman primate; regulatory T cells; transplantation
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