The CD14+CD16+ phenotype was then correlated with increased periprosthetic tissue macrophage infiltration and pathology score, plasma TNF-α and IL-1β levels, and inducible TNF-α and IL-1β production after stimulation with UHMWPE particles, paralleling findings of CD14+CD16+ monocytes in rheumatoid arthritis.29 Coupled with the findings that TNF-α can increase CD16 expression52 and precede CD16+ monocyte expansion,29 Wu et al. concluded that TNF-α and CD16 likely form an auto-amplification loop. The gene discussed is CD14; the disease is rheumatoid arthritis.