Anti-human MD-2 18H10 mAb binds to HEK293 cell transfectants expressing human MD-2 either with human TLR4 or rabbit TLR4, but not to rabbit MD-2. The specificity of the 18H10 antibody is shown by flow cytometry analysis of HEK293 cells transiently transfected with either human TLR4 and human MD-2 (A, E, and I), rabbit TLR4 and rabbit MD-2 (B, F, and J), human TLR4 and rabbit MD-2 (C, G, and K), or rabbit TLR4 and human MD-2 (D, H, and L). Cells were incubated with anti-FLAG mAb (to detect TLR4 expression), anti-C-myc mAb (to detect MD-2 expression), or the anti-human MD-2 18H10 mAb followed by an allophycocyanin (APC)-coupled anti-mouse IgG antibody.