title: The effects of an anti-CD4 monoclonal antibody, keliximab, on peripheral blood CD4+ T-cells in asthma.
abstract: CD4+ T-cells are likely to be involved as a source of pro-inflammatory cytokines in asthma. This study assessed the effects of an infusion of keliximab (IDEC CE9.1), an anti-CD4+ monoclonal antibody, on peripheral blood CD4+ T-cells in corticosteroid-dependent asthmatics. Three cohorts of patients (termed C0.5: n=6, C1.5: n=5, and C3.0: n=5) received a single infusion of 0.5, 1.5 or 3.0 mg x kg(-1), respectively, with a fourth receiving placebo (Cpl: n=6), and were followed-up for 4 weeks. By flow cytometry in peripheral blood, pre- and postinfusion assessment was made of: a) CD4 and CD8 counts and mean fluorescence; b) CD25, human leukocyte antigen-DR (HLA-DR), CD45RO and CD45RA expression on CD4+ T-cells; and c) interferon (IFN)-gamma, interleukin (IL)-4 and IL-5 expression in CD4+ T-cells. Keliximab's in vitro effects on allergen-specific peripheral blood mononuclear cells (PBMC) proliferation in atopic asthmatics were also evaluated. There was a significant increase in lung function (peak expiratory flow rate) in the C3.0 group. Following infusion in C0.5, C1.5 and C3.0 but not Cpl: 1) the CD4, but not CD8 count was significantly decreased; 2) there was total loss of Leu3a staining; 3) there were significant reductions in the mean fluorescence of OKT4 binding; and 4) there were significant reductions in the numbers of CD25, HLA-DR, CD45RO and CD45RA/CD4+ cells. There were no changes in CD4+ cell expression of IFN-gamma, IL-4 or IL-5. Keliximab caused a significant reduction in T-cell proliferation as compared to a control monoclonal antibody. Keliximab, as an anti-CD4 monoclonal antibody, leads to a transient reduction in the number of CD4+ T-cells and modulation of CD4+ receptor expression in severe asthmatics. The effects of keliximab may be mediated through a decrease in CD4+ surface expression and T-lymphocyte numbers, in addition to a reduction in allergen-induced proliferation.
authors.affiliation: Department of Allergy and Clinical Immunology, Imperial College School of Medicine, National Heart and Lung Institute, London, UK.
authors.forename: O M
authors.initials: OM
authors.lastname: Kon
authors.forename: B S
authors.initials: BS
authors.lastname: Sihra
authors.forename: L C
authors.initials: LC
authors.lastname: Loh
authors.forename: J
authors.initials: J
authors.lastname: Barkans
authors.forename: C H
authors.initials: CH
authors.lastname: Compton
authors.forename: N C
authors.initials: NC
authors.lastname: Barnes
authors.forename: M
authors.initials: M
authors.lastname: Larché
authors.forename: A B
authors.initials: AB
authors.lastname: Kay
mesh_terms: D000328:Adult; D000911:Antibodies, Monoclonal / Q000009:adverse effects / Q000627:therapeutic use*; D001249:Asthma / Q000188:drug therapy* / Q000276:immunology; D015704:CD4 Antigens / Q000276:immunology*; D018791:CD4 Lymphocyte Count; D015331:Cohort Studies; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D008213:Lymphocyte Activation / Q000187:drug effects / Q000276:immunology; D008297:Male; D012130:Respiratory Hypersensitivity / Q000188:drug therapy / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D015704:CD4 Antigens; C121251:keliximab