Anti-Human IL-33 Antibody - Western Blot. Western blot of anti-Human IL-33 antibody shows detection of a band ~18 kD in size corresponding to recombinant human IL-33 (lane 1). The identity of the higher molecular weight band is unknown. Molecular weight markers are also shown (M). After transfer, the membrane was blocked overnight with 3% BSA in TBS followed by reaction with primary antibody at a 1:1000 dilution. Detection occurred using peroxidase conjugated anti-Rabbit IgG (LS-C60865) secondary antibody diluted 1:40000 in blocking buffer (p/n MB-070) for 30 min at RT followed by reaction with FemtoMax chemiluminescent substrate. Image was captured using VersaDoc MP 4000 imaging system (Bio-Rad).