title: GM-CSF does not increase CD20 antigen expression on chronic lymphocytic leukemia lymphocytes.
abstract: CD20 antigen expression in B-chronic lymphocytic leukemia (B-CLL) is at significantly lower levels than in non-Hodgkins lymphoma, which may affect the degree of anti-CD20 antibody binding. Low density of CD20 expression on malignant cells may explain the lower response rates to anti-CD20 monoclonal antibody, observed in B-CLL. Upregulating the antigen receptor intensity on tumor cells may enhance the response rates. In this study, we examined the influence of granulocyte macrophage-colony stimulating factor (GM-CSF) on the expression level of CD20 antigen and percent of cells expressing CD20 antigen on B-CLL lymphocytes, in vivo. CD20 antigen expression was studied by flow cytometry at baseline, 12 and 24 h after GM-CSF injection. However neither upregulation of CD20 antigen nor a change of the proportion of CD20 positive cells was observed after a dose of 5 microg/kg GM-CSF. Strategies other than GM-CSF priming needs to be evaluated in order to increase the efficacy of anti-CD20 monoclonal antibodies in B-CLL.
authors.affiliation: Department of Hematology, Gazi Medical School, Birlik mah, 18 sok 5/5, Ankara, Turkey. ayagci@gazi.edu.tr
authors.forename: Münci
authors.initials: M
authors.lastname: Yağci
authors.forename: Irem
authors.initials: I
authors.lastname: Akar
authors.forename: Gülsan Türköz
authors.initials: GT
authors.lastname: Sucak
authors.forename: Rauf
authors.initials: R
authors.lastname: Haznedar
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000235:genetics; D018951:Antigens, CD20 / Q000235:genetics*; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000276:immunology*; D008228:Lymphoma, Non-Hodgkin / Q000276:immunology; D051379:Mice
chemical_list: D015703:Antigens, CD; D018951:Antigens, CD20; D016178:Granulocyte-Macrophage Colony-Stimulating Factor