Enhanced Fc receptor function of monocytes from patients with clinically active systemic lupus erythematosus : Binding and degradation of soluble immune complexes in vitro.

Abstract

The in vitro Fc receptor function of monocytes as measured by using soluble immunecomplexes (IC) consisting of ovalbumin and 12SI-labeled antibody to ovalbumin was examined in serum-free medium. Adherent monocytes were obtained from peripheral blood of 18 patients with systemic lupus erythematosus (SLE; 6 active, 12 inactive) and 13 normal controls. 5xlO5 monocytes were incubated with soluble IC containing 20 ng IgG for 16 hr at 4°C, and for 4 hr and 16 hr at 37°C, and then cell-associated and acid-soluble radioactivities were counted. After 16-hr incubation at 4°C, there was no significant difference in the amount of cell-associated IC between monocytes from SLEpatients and those from normal controls. After 4 hr incubation at 37°C, monocytes from patients with active SLE bound and phagocytized more IC than those from patients with inactive SLE or from normal controls (P<0.01). After 16 hr incubation at 37°C, degradation of soluble IC by monocytes from patients with active SLE greatly increased (P<0.003).These findings were discussed in relation to the possible pathophysiologic role of the mononuclear phagocyte system in SLE.

Immune complexes as culprits of immunopathology in severe COVID-19

“…SLE is characterized by circulating autoreactive antibodies that deposit in tissues, including skin, kidneys, and brain. Here, IC deposition elicits a progressive inflammatory response resulting in tissue damage [ 5 ] and further release of autoantigens at a given point [ 6 – 9 ]. This self-propelling process eventually drives severe systemic inflammation, which can often only be controlled by the administration high-dose glucocorticoids and cyclophosphamide.…”