A new device for selective removal of CD4+ T cells

Cytapheresis with a filter for selective removal of CD4+ T cells in experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is a major animal model of human multiple sclerosis (MS). CD4+ T cells are thought to play a pivotal role in the patho genesis of EAE and MS. In order to investigate the depletio n of CD4+ T cells from the systemic circulation as an effective strategy for the treatment of MS, we performed extracorporeal CD4+ T cell adsorption, using a filter to which anti-CD4+ antibody is immobilized as a ligand, in adoptively transferred EAE. Rats treated with CD4+ T cell removal filter (C D4RF) exhibited milder clinical signs of EAE and earlier recovery than those receiving sham treatment. Moreover, the thymic cells from EAE rats treated with C D4RF exhibited a suppressed proliferative response and IFN-g production to myelin basic protein. These results suggest that depletion of CD4+ T cells from the systemic circulation by extracorporeal treatment is a potentially useful strategy for treatment of acute phase and relapsing MS.

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

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.

Poly(N-isopropylacrylamide)-graft-polypropylene membranes containing adsorbed antibody for cell separation

We developed a novel selective cell-separation method based on using a poly(N-isopropylacrylamide)-graft-polypropylene (PNIPAAm-g-PP) membrane containing adsorbed monoclonal antibody specific to the target cell. This membrane was prepared by plasma-induced polymerization and soaking in an antibody solution at 37 degrees C. Poly(N-isopropylacrylamide) has a thermoresponsive phase transition: at 32 degrees C water-insoluble (hydrophobic) and water-soluble (hydrophilic) states interconvert. Adsorption of antibody onto PNIPAAm-g-PP membrane at 37 degrees C and its desorption at 4 degrees C was verified by fluorescence-microscopy of the PNIPAAm-g-PP membrane after soaking it in fluorescein-conjugated goat anti-mouse IgG in phosphate-buffered saline. PNIPAAm-g-PP membranes containing adsorbed anti-mouse CD80 monoclonal antibody preferentially captured mouse-CD80 transfected cells at 37 degrees C compared with membranes lacking antibody or containing anti-mouse CD86 monoclonal antibody. Detachment of captured cells from PNIPAAm-g-PP membranes was facilitated by washing at 4 degrees C because of the thermoresponsive phase transition of PNIPAAm. With this method, mouse CD80- or mouse CD86-transfected cells were enriched from a 1:1 cell suspension to 72% or 66%, simply and with high yield.

Development of a device for selective removal of CD4+ T cells

To control antigen (Ag)-specific immune cells is important in the treatment of autoimmune diseases. In particular, controlling the immune response of autoimmune T cells is effective in the treatment of these diseases. The development of a device that can remove CD4+ T cells specifically by extracorporeal circulation is now in progress, with the aim to deplete autoimmune T cells. We developed a removal material made of polypropylene non-woven fabrics with anti human CD4 monoclonal antibody immobilized on the surface. Using a column packed with the removal material, we succeeded in removing CD4+ T cells specifically from peripheral whole blood by direct perfusion. Moreover, CD4+ T cells can be specifically removed even from blood with lower surface antigen density by in vitro activation.

Apheresis of immune diseases and apheresis using immunological specificity

It has been clearly shown that autoimmune diseases can be treated by apheresis by eliminating immune complexes, however, the effects of therapeutic apheresis are not limited to immune disorders. Almost all diseases are associated with immune systems. Immune systems can be regulated by advanced techniques of apheresis, including immunoadsorption and immunocytapheresis, removing immune effector molecules and various immune-associated cells selectively. Therefore, apheresis can be used as a nondrug treatment for many diseases. In addition, disease-associated proteins that cause disease or are produced in the course of diseases and accumulate in the body could be eliminated selectively by apheresis using the extremely powerful ability of the immune system to recognize polypeptide structures specifically and distinguish miniscale differences among molecules. In this article, we discuss the current status of treatment of immune diseases by apheresis and possible treatment approach of a variety of diseases by apheresis based on immune reactions.

Leukocytapheresis using a leukocyte removal filter

Leukocytapheresis (LCAP) long has been investigated with a leukocyte removal filter for the treatment of various kinds of autoimmune related and inflammatory diseases such as rheumatoid arthritis, inflammatory bowel disease, multiple sclerosis, and so on. A lot of patients with such diseases have been reported to respond to LCAP. Asahi Medical Co. has developed the leukocyte removal filter Cellsorba and an extracorporeal treatment unit Plasauto LC so that the LCAP technique can be performed easily with a high performance filter, easy attachment of the blood circuit tubing set, and automatic operation. Cellsorba E has been listed as a medical device reimbursed by Japanese national health insurance to be used in LCAP for active ulcerative colitis since October 2001. Although the effective mechanism of LCAP is still controversial, the removal of activated leukocyte from the peripheral blood and the reaction by blood contacting materials in Cellsorba can be triggers of the immunomodulation for the treatment of immune disorder. This review introduces the development of LCAP technologies and several reports on therapeutic results.

Basic clinical study of an easy and effective leukocytapheresis by the use of nonwoven polyester filter

Leukocytapheresis (LCAP) is widely used for the treatment of immunological diseases. We studied a new treatment of LCAP using a nonwoven polyester filter. In a basic study, 30-70% of the lymphocytes were adsorbed. Also, 30-68% of the lymphocyte subsets were removed. This method was applied to 2 patients with corticosteroid-resistant active ulcerative colitis. Erosion, edema, bleeding, ulcer formation, and stenosis of the colon were almost completely repaired after 6 LCAP treatments. LCAP using a nonwoven polyester filter will be a very useful treatment for immunological diseases and extracorporeal immunomodulation.