TNF and rheumatoid arthritis: Based on LTF-specific IgG Ab screening results of our earlier study on RA sera (17), serum samples from four patients with high titer anti-LTF autoantibodies were added to wells precoated with hLTF, the plate-bound ICs thus formed exhibited capability to induce TNFα production by (M-CSF)-M2 cells (Figure 1C).