Microcolumn affinity test results for binding of HVEM(23–39) fragment to BTLA: (A) supernatant, (B) last wash and (C) elution fractions. The MS measurements were done with the use of MALDI TOF/TOF 5800 (ABSciex, Germany). As a matrix α-cyano-4-hydroxycinnamic acid (CHCA, 10 mg/ml, Sigma-Aldrich) was used. The measurements were done in reflector positive mass mode with previous mass calibration with commercial standard peptide mixture (The Peptide Mass Standards Kit for Calibration of AB SCIEX MALDI-TOF™ Instruments).