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Clinical Competence↗
Biomedical subjects
E Nylander Lundqvist
Publications and source records attributed to E Nylander Lundqvist.
Binding of tissue plasminogen activator to human endothelial cells. Importance of the B-chain as a ligand.
The aim of the present study was to investigate the binding of tissue plasminogen activator (tPA) to cultured endothelial cells and to characterize binding structures present in the cultures. Studies on the binding of 125I-tPA to cultured endothelial cells from human umbilical-cord veins (HUVEC) indicated that the number of sites for specific binding of tPA is 8 x 10(5) per cell. Treatment with an excess of antibodies against plasminogen-activator inhibitor type 1 (PAI-1) caused an 80% decrease in the binding, leaving about 1.6 x 10(5) unoccupied binding sites per cell, which appeared to be different from PAI-1. About 1.9 x 10(5) binding sites/cell for tPA were found on the surface of HUVEC that had been detached from the matrix. This indicates that only minor amounts of PAI-1 occur on the surface of the cells. In addition, immunocytochemical analysis showed that PAI-1 antigen is present almost exclusively in the cytoplasm but was not observed on the surface of the cells, whereas tPA antigen is abundant on the plasma membrane of tPA-treated cells as well as intracellularly. Competition studies using unlabelled compounds showed that native tPA and tPA B-chain (the proteinase domain), as well as the inactive derivatives, B-chain inactivated with D-Phe-Pro-Arg-chloromethane and tPA-PAI-1 complex, caused a considerable quenching of the binding of 125I-tPA to HUVEC, whereas the isolated A-chain had no demonstrable effect. Two components (apparent molecular masses 38 kDa and 56 kDa) reacting with tPA but lacking PAI-1 antigen determinants were identified. Thus the data suggest that tPA binds to HUVEC by two principally different mechanisms. One is mediated by PAI-1, which binds and inactivates tPA with a functional active site. The other binding is achieved by components which react with sites on the activator molecule other than structures of the A-chain or the active site.
Cell Membrane↗
Prevalence of anti-endothelial cell antibodies in patients with autoimmune diseases.
The prevalence of anti-endothelial cell antibodies (AECA) of IgA, IgG and IgM classes was studied by means of enzyme-linked immunosorbent assays (ELISA) in 466 patients with autoimmune/inflammatory disorders. The reference limits in the ELISAs for the AECA were determined from a random population sample of 249 subjects. The frequency of AECA was highest in patients with SLE (n = 42), 14.6% mainly of IgG class, and the presence of AECA correlated with disease activity in these patients. In the RA patient group (n = 200), 9.5% had AECA, mostly of IgA type. We found no association between the presence of AECA and extra-articular manifestations of RA or survival rate. In patients with undefined connective tissue disease (n = 57), ankylosing spondylitis (n = 109), and psoriatic arthritis (n = 58), the frequency of AECA corresponded to that of the random population sample. In a cohort of samples sent to the laboratory for determination of anti-nuclear antibodies (ANA) there was a correlation between the presence of ANA and AECA. Our findings indicate that RA patients are characterized by IgA class AECA, whereas SLE patients have IgG class AECA also correlating to disease activity.
Adult↗