title: Exploring the feasibility of selective depletion of T lymphocyte subsets by whole blood immunoadsorption cytapheresis.
abstract: Normal turnover of T lymphocytes is slow relative to other blood cells. Consequently, the physical removal of circulating leucocytes by thoracic duct drainage, repeated leukapheresis or blood filtration results in T cell depletion and immunosuppression. However, clinical use of such procedures is impractical compared with immunosuppressive drugs or radiation. None the less, immunosuppression by physical depletion of T cells, avoiding the systemic toxicities of drugs and radiation, might have clinical advantages if immunophenotypically distinct T cell subsets could be depleted selectively. Recent advances in targeted plasma protein apheresis using adsorbent macrobead columns prompted us to determine whether analogous techniques might permit CD4+ T lymphocytes to be removed selectively from whole blood. To explore this possibility, we linked murine anti-human-CD4 and isotype-identical control monoclonal antibodies (mAbs) to agarose, polyacrylamide and polystyrene macrobeads (150-350 microm) and then evaluated the selectivity, specificity and efficiency of macrobead columns to remove CD4+ T cells from anti-coagulated whole blood at varying mAb densities and flow rates. We also examined saturation kinetics and Fc-oriention versus random coupling of mAbs to macrobeads. Sepharose 6MB macrobead (250-350 microm) columns proved to be most effective, selectively removing up to 98% of CD4+ T cells from whole blood. Moreover, depletion efficiency and selectivity were retained when these columns were reused after elution of adherent CD4+ cells. These studies indicate that selective depletion of T lymphocyte subsets by whole blood immunoadsorption apheresis using mAb-linked macrobead columns may be feasible on a clinical scale. It is possible that such apheresis techniques could achieve targeted forms of immunosuppression not possible with drugs or radiation.
authors.affiliation: Section of Hematology and Oncology, Department of Medicine, Boston University Medical Center, Boston, MA, USA. belakm@mail.nih.gov
authors.forename: M
authors.initials: M
authors.lastname: Belak
authors.forename: C R
authors.initials: CR
authors.lastname: Valeri
authors.forename: D G
authors.initials: DG
authors.lastname: Wright
mesh_terms: D000180:Acrylic Resins; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D018791:CD4 Lymphocyte Count; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D005240:Feasibility Studies; D007937:Leukapheresis / Q000295:instrumentation / Q000379:methods*; D008212:Lymphocyte Depletion / Q000295:instrumentation / Q000379:methods*; D051379:Mice; D011137:Polystyrenes; D012685:Sepharose / Q000031:analogs & derivatives; D000099166:Polyacrylamides
chemical_list: D000180:Acrylic Resins; D000911:Antibodies, Monoclonal; D011137:Polystyrenes; D012685:Sepharose; D000099166:Polyacrylamides; C039745:Sepharose 6MB