Complex sentence: RA primarily starts as a state of persistent cellular activation leading to autoimmunity and immune complexes in both joints as well as other organs where it manifests.Initial site of disease is synovial membrane where swelling and congestion leads to infiltration by immune cells.
Split into simpler sentences: RA primarily starts as a state of persistent cellular activation leading to autoimmunity and immune complexes in both joints and other, organs where it manifests. The initial site of disease is the synovial membrane, where swelling and congestion leads to infiltration by immune cells.