Showing papers by "Eng M. Tan published in 1981"

A nuclear antigen associated with cell proliferation and blast transformation.

Abstract: A nuclear antigen associated with cell proliferation (proliferating cell nuclear antigen-PCNA) and blast transformation is recognized by autoantibodies in the sera of some patients with systemic lupus erythematosus This autoantibody is a precipitating antibody and also reacts in immunofluorescence, staining the nucleoplasm of proliferating and blast-transformed cells The autoantibody was used as a reagent to determine the distribution of PCNA in a synchronized continuous B lymphoid cell line (WiL-2) and in mitogen-induced blast-transformed lymphocytes In WiL-2 cells, PCNA was detected as speckled nucleoplasmic staining in G1, S, and G2 phases of the cell cycle In addition, during late G1 and early S phases, PCNA was also detected in the nucleolus During mitogen-induced blast transformation of lymphocytes, PCNA was noticed in the nucleolus before the initiation of DNA synthesis and later became nucleoplasmic with disappearance of nucleolar staining These studies demonstrate that the relationship of PCNA to proliferation and blast transformation may be associated with events related to DNA synthesis in these cells

Isolation of circulating immune complexes by conglutinin and separation of antigen from dissociated complexes by immobilized protein A.

Abstract: A method for the isolation of complement-fixing immune complexes from human serum and the separation of antigen from antibody is described. In order to isolate the complexes, we used soluble bovine conglutinin in a three-step procedure: (1) serum containing immune complexes is reacted with conglutinin in the presence of 10 mM calcium; (2) the conglutinin-bound immune complexes are precipitated by anti-conglutinin rabbit serum; (3) the precipitate is washed and the complexes are eluted from the precipitate by EDTA (pH 7.5) which chelates calcium and releases C3-associated immune complexes from conglutinin. To separate the antigen from the antibody, the isolated complexes are acid-dissociated (pH 3.0), and the antibody is absorbed to staphylococcal protein A conjugated to Sepharose leaving the antigen in solution. The antibody bound to Sepharose-protein A is recovered by elution with 3.5 M magnesium chloride. This procedure permitted the isolation of immune complexes from sera of hepatitis B surface antigen (HBsAg) positive chronic active hepatitis. In addition, immune complexes were isolated from sera of patients with rheumatoid arthritis, systemic lupus erythematosus and primary biliary cirrhosis. The isolated immune complexes contained IgG, IgM, C3 and albumin. Specific antibodies such as rheumatoid factors, anti-nuclear antibodies and antimitochondrial antibodies in varying titres have been found to be present in the isolated immune complexes. The conglutinin method has proven to be a useful technique for the isolation of immune complexes and for the identification of antibody and could be applied to the identification of the antigen in immune complexes.