The specificity of anti-TREM2 antibodies. The specificity of seven commercially available anti-TREM2 antibodies was determined by Western blot analysis of recombinant human TREM2 protein expressed in HEK293 cells following transfection of the expression vector. The upper panels represent (a) HPA010917 (at the final concentration of 200 ng/mL), (b) AF1828 (100 ng/mL), (c) 2B5 (1 μg/mL), (d) bs-2723R (2 μg/mL), (e) ab69405 (400 ng/mL), (f) ab85851 (500 ng/mL), and (g) PA5-18763 (500 ng/mL). The lower panels indicate the corresponding blots of the upper panels with an antibody against HSP60, an internal control of protein loading. The lanes represent the protein extract (80 μg each) of (1) nontransfected and (2) transfected HEK293 cells. The position of TREM2 is indicated by an arrowhead.