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Updated: Aug 14, 2026
The Nijmegen Hemostasis Assay: Simultaneous Fluorogenic Measurement of Thrombin and Plasmin Generation in a Single Well
Published on: February 27, 2026
Identification of polyclonal and monoclonal antibodies against tissue plasminogen activator in the antiphospholipid
Cai-Sheng Lu1, Arash A Horizon, Kwan-Ki Hwang
1University of California, Los Angeles, CA 90095, USA.
Objective:
To test the hypotheses that some plasmin-reactive anticardiolipin antibodies (aCL) may bind to tissue plasminogen activator (tPA) and that some of the tPA-reactive aCL may inhibit tPA activity.
Methods:
We studied the reactivity of 8 patient-derived monoclonal aCL with tPA and examined the presence of IgG anti-tPA antibodies in patients with the antiphospholipid syndrome (APS). The effects of the reactive monoclonal aCL on the activity of tPA were also examined.
Results:
Six patient-derived plasmin-reactive monoclonal aCL bound to tPA. Analysis of plasma samples revealed that 10 of 80 APS patients (12.5%) and 1 of 81 systemic lupus erythematosus patients (1.2%) had antibodies against fibrin-associated tPA, based on a cutoff value equal to the mean + 2SD of the level in 28 normal subjects. Of the 6 tPA-reactive monoclonal aCL, 2 of them (CL1 and CL15) inhibited tPA activity.
Conclusion:
Some of the plasmin-reactive aCL in APS patients may bind to tPA. Of the tPA-reactive aCL, some (such as CL1 and CL15) may inhibit tPA activity and, thus, may be prothrombotic in the host.
