Mice were also injected intraperitoneally with 300 ng Pertussis toxin (PT; List Biological Laboratories) in 200 μL PBS (final concentration 1.5 μg/mL) on the day of immunization and 2 d later. Both male and female mice were used and were distributed in equal numbers
Mice were immunized weekly for 1, 6, or 12 weeks by oral gavage with ground blanched peanut (Western Mixers Produce & Nuts), roasted and unsalted peanut (Whole Foods Market), or wheat flour (Bob’s Red Mill Company) or OVA (Sigma) at 5 mg food antigen, with or without 10 g of CT (List Biologicals, lot nos. 10165A1 and 10167A2) or 100 g of Alternaria alternata and Alternaria tenuis extract (Greer Laboratories, lot no. 322776) in 200 l of 0.2 M sodium bicarbonate buffer per mouse based on a protocol modified from (52)
Cells were maintained in 5% CO 2 at 37°C. B cells were stimulated with LPS 0111:B4 (10 μg/ml, List Biological Laboratories, Campbell, CA, United States), 100 ng/ml CD40L (R&D Systems, Minneapolis, MI, United States), 10 ng/ml Interleukin-4 (R&D Systems), and Cached
LPS (Ultrapure Salmon- ella Minnesota R595, List Biological Laboratories Inc., Campbell, CA) and other TLR ligands (Invivogen) were added at the indicated concentrations. Stimulation with immune complexes was performed as previously de- scribed 
The tumor necrosis factor (TNF) superfamily cytokine TNF-like protein 1A (TL1A) and its receptor DR3 are essential for diverse animal models of autoimmune disease and may be pathogenic in rheumatoid arthritis (RA). However, the relationship of TL1A to disease duration, activity, and response to anti-TNF and other therapies in RA is not clear. We measured soluble TL1A in synovial fluid (SF), serum, or plasma from RA first-degree relatives (FDRs) and in early RA and established disease. We measured the effects of anti-TNF and methotrexate (MTX) therapy on circulating TL1A from multiple independent RA treatment trials. We also determined the ability of a blocking anti-TL1A antibody to inhibit clinical disease and articular bone destruction in the murine collagen-induced arthritis (CIA) model of human RA. Soluble TL1A was specifically elevated in the blood and SF of patients with RA compared to patients with other diseases and was elevated early in disease and in at-risk anti-cyclic citrullinated peptide (CCP) (+) first-degree relatives (FDRs). Therapeutic TNF inhibition reduced serum TL1A in both responders and non-responders, whereas TL1A declined following MTX treatment only in responders. In murine CIA, TL1A blockade was clinically efficacious and reduced bone erosions. TL1A is specifically elevated in RA from early in the disease course and in at-risk FDRs. The decline in TL1A after TNF blockade suggests that TL1A levels may be a useful biomarker for TNF activity in RA. These results support the further investigation of the relationship between TL1A and TNF and TL1A blockade as a potential therapeutic strategy in RA.