Problem Studies on experimental antiphospholipid syndrome (APS) models proved that molecular mimicry between plasma protein β2-glycoprotein I (β2GPI) and structure within micro-organisms or their products, might be a cause for experimental APS. Considering the heterogeneity of polyclonal antiphospholipid antibodies (aPLs), it is important to define the precise characteristics of pathogenic aPLs. To avoid the influence of polyclonality and to further analyse the connection between molecular mimicry and APS, we produced monoclonal antibodies (MAbs) against tetanus toxoid (TTd) and tested their reactivity against β2GPI.
Method of study In this report, we analysed the characteristics of MAb26 raised against TTd and cross-reactive with β2GPI: its binding properties in various in vitro immunoassays, its specific interactions with surface epitopes expressed on apoptotic cells and its role in vivo.
Results We have demonstrated that MAb26: (i) binds β2GPI being immobilized on an appropriate surface: irradiated polystyrene plates, non-irradiated plates pre-coated with anionic phospholipids and polyvinylidene fluoride membrane; (ii) binds specifically to apoptotic but not to viable cells and the binding is β2GPI-dependent; and (iii) induces a pathologic pregnancy outcome when passively injected into BALB/c mice.
Conclusion This study concluded that certain subpopulations of antibodies raised against TTd and cross-reactive with β2GPI, because of the molecular mimicry mechanism, could have pathologic potential.