CXCL8 and Arthritis: In keeping with this theory, the authors speculate that in cases where all other factors influencing the levels of IL-1β, IL-8, and INF γ in PB can be excluded, including Borreliosis-associated arthritis, the levels of these cytokines in PB can be further tested for a direct relationship with the SF levels in CrCL deficient stifles.