Abstract: A method of treating inflammation by administering a therapeutically effective amount of a human immunosuppressant protein (HISP) to a subject is presented. The inventors have discovered a novel immunosuppressive protein purified from the supernatant of hNT cell culture. The immunosuppressant protein has a molecular weight of about 40-100 kDa, an isoelectric point of about 4.4, a net ionic charge and is capable of suppressing T-cell activation, T-cell proliferation and the production of IL-2. This protein can be used in treating inflammation, preventing graft rejection after transplantation, treating autoimmune diseases and suppressing allergic responses as well as other uses.

Abstract: A method of treating inflammation by administering a therapeutically effective amount of a human immunosuppressant protein (HISP) to a subject is presented. The inventors have discovered a novel immunosuppressive protein purified from the supernatant of hNT cell culture. The immunosuppressant protein has a molecular weight of about 40-100 kDa, an isoelectric point of about 4.4, a net ionic charge and is capable of suppressing T-cell activation, T-cell proliferation and the production of IL-2. This protein can be used in treating inflammation, preventing graft rejection after transplantation, treating autoimmune diseases and suppressing allergic responses as well as other uses.

Abstract: A composition of an immunosuppressant protein (HISP) which is achieved by the steps of obtaining supernatant from hNT neuronal cells; exposing the supernatant to preparative polyacrylamide gel; placing the active isoelectric fraction on a Blue Sepharose column to bind albumin; and collecting the free fraction containing the concentrated, isolated HISP. The HISP is anionic, has a molecular weight of 40-100 kDa, an isoelectric point of about 4.8 and is obtained from the supernatant of hNT cells. HISP can suppress proliferation of responder peripheral blood mononuclear cells in allogeneic mixed lymphocyte cultures; HISP can suppress T-cell proliferation and IL-2 production in response to phorbol 12-myristate 13-acetate (PMA), ionomycin and concanavalin-A. HISP does not act through the T-cell receptor-CD3 complex or via altered accessory signal cells.

Abstract: A method for purifying an immunosuppressant protein (HISP) has the steps of obtaining supernatant from hNT cells; exposing the supernatant to preparative polyacrylamide gel electrophoresis to produce 20 isoelectric fractions, including active isoelectric fraction #10; placing the active isoelectric fraction on a Blue Sepharose column to bind albumin; and collecting the free fraction containing the concentrated, isolated HISP. Also disclosed is a method of treating inflammation, using an effective amount of an HISP. The HISP is anionic, has a molecular weight of 40-100 kDa, an isoelectric point of about 4.8 and is obtained from the supernatant of hNT cells, but not from NCCIT embryonal carcinoma cells. T98G glioblastoma cells or THP-1 monocytic leukemia cells. HISP can maintain T cells in a quiescent G.sub.0/G.sub.1 state without lowering their viability. HISP loses activity when treated with heat, pH2, pH11, or mixed with trypsin or carboxypeptidase, but not with neuraminidase.

Abstract: A method for purifying an immunosuppressant protein (HISP) has the steps of obtaining supernatant from hNT cells; exposing the supernatant to preparative polyacrylamide gel electrophoresis to produce 20 isoelectric fractions, including active isoelectric fraction #10; placing the active isoelectric fraction on a Blue Sepharose column to bind albumin; and collecting the free fraction containing the concentrated, isolated HISP. Also disclosed is a method of treating inflammation, using an effective amount of an HISP. The HISP is anionic, has a molecular weight of 40-100 kDa, an isoelectric point of about 4.8 and is obtained from the supernatant of hNT cells, but not from NCCIT embryonal carcinoma cells, T98G glioblastoma cells or THP-1 monocytic leukemia cells. HISP can maintain T cells in a quiescent G0/G1 state without lowering their viability. HISP loses activity when treated with heat, pH2, pH11, or mixed with trypsin or carboxypeptidase, but not with neuraminidase.

Abstract: A method for purifying an immunosuppressant protein (HISP) has the steps of obtaining supernatant from hNT cells; exposing the supernatant to preparative polyacrylamide gel electrophoresis to produce 20 isoelectric fractions, including active isoelectric fraction #10; placing the active isoelectric fraction on a Blue Sepharose column to bind albumin; and collecting the free fraction containing the concentrated, isolated HISP. Also disclosed is a method of treating inflammation, using an effective amount of an HISP. The HISP is anionic, has a molecular weight of 40-100 kDa, an isoelectric point of about 4.8 and is obtained from the supernatant of hNT cells, but not from NCCIT embryonal carcinoma cells, T98G glioblastoma cells or THP-1 monocytic leukemia cells. HISP can maintain T cells in a quiescent G0/G1 state without lowering their viability. HISP loses activity when treated with heat, pH2, pH11, or mixed with trypsin or carboxypeptidase, but not with neuraminidase.