Exploring the feasibility of selective depletion of T lymphocyte subsets by whole blood immunoadsorption cytapheresis

• Published in: Clinical and experimental immunology Vol. 150; no. 3; pp. 477 - 486
• Main Authors: Belak, M, Valeri, C.R, Wright, D.G
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01-12-2007; Blackwell Publishing Ltd; Blackwell; Blackwell Science Inc
• Subjects: Acrylic Resins; Analytical, structural and metabolic biochemistry; Animals; Antibodies, Monoclonal - immunology; Biological and medical sciences; CD4; CD4 Lymphocyte Count; CD4-Positive T-Lymphocytes - immunology; Feasibility Studies; Fundamental and applied biological sciences. Psychology; immunoadsorption cytapheresis; immunosuppression; Leukapheresis - instrumentation; Leukapheresis - methods; lymphocyte depletion; Lymphocyte Depletion - instrumentation; Lymphocyte Depletion - methods; Mice; Molecular and cellular biology; Molecular biophysics; Polystyrenes; Sepharose - analogs & derivatives; Translational Studies; lymphocyte depletion; Cytapheresis; Biochemistry; Biophysics; Immunosorption; Cell subpopulation; Whole blood; Immunosuppression; CD4; Depletion; T-Lymphocyte; Feasibility; Molecular biology; immunoadsorption cytapheresis
• ISSN: 0009-9104; 1365-2249
• DOI: 10.1111/j.1365-2249.2007.03518.x

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 μm) 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 μm) 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.