LTF and rheumatoid arthritis: It was found that Lf-ICs were elevated in the serum of patients with rheumatoid arthritis and led to the activation of human monocytes/macrophages and inflammatory pathways via synergistic signalling through CD14/toll-like receptor (TLR) 4 and Fc RIIa (CD32a), triggering the production of proinflammatory cytokines IL-1, IL-6, and TNF-α [34].