This arthritis development following i.a. injection of only saline, which by itself does not lead to arthritis [25], could be due to the prior presence of the GPI (glucose-6-phosphate isomerase) antibodies and their immune complexes in the injected joint (from the K/BxN serum transfer [32]), contributing to the prolongation of the normally acute inflammatory response associated with the trauma of the injection and leading subsequently to arthritis development in that joint. Here, GPI is linked to Arthritis.