Nisihara R, et al. – The clinicians intended to figure out whether mannose-binding lectin (MBL) deficiency in patients with ankylosing spondylitis (AS) predisposes to infections. They found a significant association between MBL deficiency and a higher risk of tuberculosis and urinary tract infection in patients with AS. However, further studies were required to confirm these findings.

• In this study, 60 patients with AS diagnosed according to the Assessment of SpondyloArthritis international Society (ASAS) criteria were analyzed. 
• Their MBL serum levels were also evaluated.
• 25 individuals were identified as MBL deficient (serum values 100 ng/mL). 
•  These patients were paired with 35 “sufficient” MBL producers (median serum level = 700 ng/mL; range 150–4100 ng/mL) for gender, age, use of medications, and tobacco exposure.
• Medical records of all patients were retrospectively investigated for the period of 5 years and the rate of infection occurrence was compared in the two groups.
• AS patients with MBL deficiency had higher number of urinary tract infections (p = 0.03; IRR = 2.33; 95% CI = 0.95–6.04) and tuberculosis (p = 0.008; IRR = 9.8; 95% CI = 1.2–441.6) than controls.
• Regarding tuberculosis infection, one patient (2.8%) in the MBL-sufficient group and six (24.0%) from the deficient group had this infection.
• The MBL-sufficient patient and five from the deficient group have had latent infections, detected in the screening tests done previous to anti-TNF drug use.
• The other, in the deficient group, had lung infection while not on anti-TNF treatment. 
• Another patient, from the deficient group, has had tuberculosis skeletal infection in the past.