The role of microparticles in the generation of immune complexes in murine lupus

Systemic lupus erythematosus is a systemic inflammatory disease characterized by antibodies to nuclear molecules in association with immune complex deposition. As shown previously, microparticles (MPs), which are small membrane-bound vesicles released from dying and activated cells, contain nucleic acids and can form immune complexes found in patient blood. To assess the role of MPs in murine lupus, we used flow cytometry to measure the presence of MPs with bound IgG in the blood of MRL-lpr/lpr and NZB/W mice. These studies showed much higher numbers of MPs with bound IgG in the blood of MRL lpr/lpr compared to NZB/W mice. Furthermore, these studies showed that antibodies from MRL-lpr/lpr mice bound better to MPs from apoptotic cells than those from NZB/W mice. Together, these studies indicate important differences in the serological features of the two strains as reflected by the capacity of antibodies to bind to MPs.

► Blood of lupus mice contains microparticles with IgG as shown by flow cytometry.
► MRL-lpr/lpr and NZB/W mice differ in levels of IgG positive particles in blood.
► MRL-lpr/lpr antibodies have higher binding to microparticles than NZB/W antibodies.
► Fine specificity of lupus autoantibodies influences microparticle binding.
► The structure of immune complexes differs among strains of lupus mice.