Anti-plasminogen Autoantibodies from Plasma of Patients with Systemic Lupus Erythematosus Having Anti-phospholipid Antibody Syndrome: Isolation and Some Immunochemical Properties

L. D. Kozmin¹, I. E. Shirokova², T. A. Lisitsina², T. V. Popkova², T. M. Reschetnyak², A. G. Belenkiy², A. I. Martynov¹, and O. P. Bliznukov^1*

¹Institute of Immunology, Russian Ministry of Health, Kashirskoe sh. 24/2, Moscow, 115478 Russia; fax: (095) 118-8109; E-mail: blisnukov@mail.ru

²Institute of Rheumatology, Russian Academy of Medical Sciences, Kashirskoe sh. 34A, Moscow, 115522 Russia; fax: (095) 114-4468

^* To whom correspondence should be addressed.

Received April 1, 2002

---

Blood plasma samples from patients with systemic lupus erythematosus having the anti-phospholipid antibody syndrome were found to contain anti-plasminogen antibodies of the IgG class. The titers of anti-plasminogen autoantibodies of the IgG class were elevated in these patients compared with normal controls. Part of the pool of IgG anti-plasminogen antibodies reacts with an epitope in the lysine-binding sites of plasminogen. Anti-plasminogen IgG isolated from patients' blood plasma is specific only for a native epitope of human plasminogen passively adsorbed on immunosorbent micro-titration plate. As shown by enzyme immunoassay, autoantibodies to plasminogen of the IgG class cross-react with human fibrinogen.

---

KEY WORDS: plasminogen, autoantibodies, IgG, systemic lupus erythematosus, anti-phospholipid antibody syndrome

---