title: Promotion of natural killer cell growth in vitro by bispecific (anti-CD3 x anti-CD16) antibodies.
abstract: Bispecific heteroconjugated F(ab')2 fragments were prepared from pepsin-digested monoclonal OKT3 (anti-CD3) and 3G8 (anti-CD16) antibodies with 5,5'-dithiobis- (2-nitrobenzoic acid). When these bispecific antibodies (BsA) were added to peripheral blood lymphocyte (PBL) cultures with 100 U/ml human recombinant interleukin-2 (rIL-2), preferable growth of natural killer cells occurred. After 3 weeks the frequencies of CD56+ and CD56+3- cells in cultures with BsA were 74 +/- 7% and 65 +/- 7%, respectively, compared with 48 +/- 6% and 29 +/- 7% in control cultures. The frequencies of CD3+ lymphocytes in the presence of BsA, cells from 1-day cultures were labelled with fluorescein isothiocyanate (FITC)-conjugated anti-CD3, CD4 and CD8 monoclonal antibodies (mAb) and propidium iodide which stains dead cells. Flow cytometry revealed that more than 95% of the dead cells in cultures with BsA were CD3+. Thirty-seven per cent of CD3+, 43% of CD4+ and 17% of CD8+ cells were dead on day 1, and after 3 days the CD4+/CD8+ ratio among viable lymphocytes was 1.6 in the control and 0.5 in BsA cultures. Taken together, these results show that bispecific (anti-CD3 x anti-CD16) F(ab')2 fragments are strongly immunomodulatory by inducing the killing of T cells by CD16+ cells.
authors.affiliation: Department of Pathology, University of Helsinki, Finland.
authors.forename: A M
authors.initials: AM
authors.lastname: Malygin
authors.forename: K
authors.initials: K
authors.lastname: Somersalo
authors.forename: T
authors.initials: T
authors.lastname: Timonen
mesh_terms: D018033:Antibodies, Bispecific / Q000276:immunology*; D015703:Antigens, CD / Q000032:analysis; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D017252:CD3 Complex / Q000032:analysis / Q000276:immunology*; D015704:CD4 Antigens / Q000032:analysis; D019002:CD56 Antigen; D016827:CD8 Antigens / Q000032:analysis; D002455:Cell Division / Q000276:immunology; D002470:Cell Survival / Q000276:immunology; D002478:Cells, Cultured; D006801:Humans; D007376:Interleukin-2 / Q000276:immunology; D007694:Killer Cells, Natural / Q000276:immunology*; D017452:Receptors, IgG / Q000276:immunology*; D011994:Recombinant Proteins / Q000276:immunology
chemical_list: D018033:Antibodies, Bispecific; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D017252:CD3 Complex; D015704:CD4 Antigens; D019002:CD56 Antigen; D016827:CD8 Antigens; D007376:Interleukin-2; D017452:Receptors, IgG; D011994:Recombinant Proteins