PB0951 - Lupus Anticoagulant Phenomenon and Thrombin Generation Activity induced by Anti-Prothrombin Antibodies: an ex-vivo demonstration

Monday, June 24, 2024

13:45 – 14:45 ICT

Room: Exhibition Hall

Presenting Author(s)

Alice Barinotti, MSc

PhD-Student
University of Turin
Turin, Piemonte, Italy

Co-Author(s)

SF

Silvia Grazietta Foddai

PhD-Student
University of Turin
Turin, Piemonte, Italy
CG

Cristina Garcia

Lab Scientist
Werfen
Barcelona, Catalonia, Spain
MP

Mar Petit-Pedrol

Lab Scientist
Werfen
Barcelona, Catalonia, Spain
IG

Ingrid Gonzalez

Lab Scientist
Werfen
Barcelona, Catalonia, Spain
EM

Eduard Martinez

Lab Scientist
University of Turin
Barcelona, Catalonia, Spain
GR

Gisela Riera

Lab Scientist
Werfen
Barcelona, Catalonia, Spain
JH

Javier Hervas

Lab Scientist
Werfen
Barcelona, Catalonia, Spain
PR

Patricia Rogniat

Lab Scientist
Werfen
Barcelona, Catalonia, Spain
BM

Barbara Montarulli

Lab Scientist
Ospedale Mauriziano
Turin, Piemonte, Italy
MM

Michael Mahler

Lab Scientist
Werfen
San Diego, California, United States
SS

Savino Sciascia

Physician
University Center of Excellence on Nephrologic, Rheumatologic and Rare Diseases (ERK-Net, ERN-ReConnect and RITA-ERN Member) with Nephrology and Dialysis Unit and Center of Immuno-Rheumatology and Rare Diseases (CMID), Department of Clinical and Biological Sciences, ASL Città Di Torino and University of Turin, Turin, Italy
Turin, Piemonte, Italy
Irene Cecchi, MD,PhD

Researcher
University of Turin
Turin, Piemonte, Italy
DL

David Lucia

Lab Scientist
Werfen
Barcelona, Catalonia, Spain
Massimo Radin, MD

Researcher
University of Turin
Turin, Piemonte, Italy

Background: Lupus Anticoagulant phenomenon in antiphospholipid syndrome is thought to be caused mostly by antibodies against β2-Glycoprotein I and prothrombin (PT). The precise role of aPT and its clinical significance needs to be further investigated.

Aims: To isolate and functionally characterize aPT by testing their contribution to LA and to thrombin generation activity.

Methods: Serum from one tetra-positive female APS patient (aPL at high titers) with history of recurrent unprovoked venous thrombotic event (while under anticoagulation) and extra-criteria manifestation, was collected. Two female aged-matched healthy controls were recruited. Total IgG were purified through gel filtration. aPT were isolated employing a resin conjugated to native PT. Purified total IgG and aPT were spiked into normal pool plasma (NPP) employing different dilutions [1:3, 1:6, 1:21, 1:51]. Functional evaluation was assessed through LA testing (Silica Clotting Time-HemosIL) and TGA (Technothrombin TGA kit-Techonoclone) for each sample and dilution.

Results: When performing TGA testing on NPP enriched with HCs total IgG, we did not observe any effect on TGA curves (Figure 1). When testing the same samples for LA, SCT was not prolonged and LA ratio resulted negative at all dilutions (Figure 2).
When performing TGA testing on NPP enriched with APS patient’s total IgG, we observed a prolongation of tLag and tPeak, progressively increasing from higher to lower concentrated samples. The same was obtained with isolated aPT (Figure 1). When testing for LA, SCT testing was prolonged for both patient’s total IgG and aPT purified enriched samples, with positive LA ratios at 1:3, 1:6 and 1:21 dilutions for total IgG, and 1:3, 1:6 dilutions for anti-PT purified.

Conclusion(s): aPT antibodies isolated from a high-risk APS patient showed an overt LA activity and TGA effect when compared with healthy donors. These results might help clarifying the actual contribution of aPT to the LA phenomenon.